Biol. Rev. (2014), pp. 000–000. 1
doi: 10.1111/brv.12165
Evolutionary perspectives on human height
variation
Gert Stulp1,2,∗ and Louise Barrett3,4
1Department of Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, U.K.
2Department of Sociology, University of Groningen, Grote Rozenstraat 31, 9712 TS, Groningen, The Netherlands
3Department of Psychology, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
4Applied Behavioural Ecology and Ecosystems Research Unit, UNISA, Johannesburg, South Africa
ABSTRACT
Human height is a highly variable trait, both within and between populations, has a high heritability, and
influences the manner in which people behave and are treated in society. Although we know much about
human height, this information has rarely been brought together in a comprehensive, systematic fashion.
Here, we present a synthetic review of the literature on human height from an explicit evolutionary perspective,
addressing its phylogenetic history, development, and environmental and genetic influences on growth and
stature. In addition to presenting evidence to suggest the past action of natural selection on human height,
we also assess the evidence that natural and sexual selection continues to act on height in contemporary
populations. Although there is clear evidence to suggest that selection acts on height, mainly through
life-history processes but perhaps also directly, it is also apparent that methodological factors reduce the
confidence with which such inferences can be drawn, and there remain surprising gaps in our knowledge.
The inability to draw firm conclusions about the adaptiveness of such a highly visible and easily measured trait
suggests we should show an appropriate degree of caution when dealing with other human traits in evolutionary
perspective.
Key words: height, human, natural selection, sexual selection, evolution, ecology, development, genetics,
environment, reproductive success.
CONTENTS
I. Introduction .................................................................................................... 2
II. Variation in human height .................................................................................... 2
(1) Spatial variation in body size and height ............................................................... 2
(2) Temporal variation in height ............................................................................. 4
(a) The ups and downs of human height evolution .................................................. 4
(b) The modern secular trend in height ............................................................... 5
III. Development of height and sexual dimorphism ........................................................... 6
(1) Height across development .............................................................................. 6
(2) Why grow up, rather than out? .......................................................................... 8
(3) Sexual dimorphism in height ............................................................................ 9
IV. Genetic influences on height ................................................................................. 10
V. Life history and height ........................................................................................ 12
(1) Principles of life-history evolution ....................................................................... 12
(2) Life-history trade-offs and norms of reaction .......................................................... 13
(3) Height and sexual maturity in contemporary industrial populations .............................. 13
(4) Variation in growth: adaptive, constrained or pathological? ......................................... 14
(5) Mortality, growth and height ............................................................................. 15
* Address for correspondence (Tel: +44(0)20 7299 4673; E-mail: gert.stulp@lshtm.ac.uk).
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2 Gert Stulp and Louise Barrett
VI. Natural selection on height ................................................................................... 16
(1) Mortality risks and height ................................................................................ 16
(a) Height, health and mortality in adults ............................................................. 16
(b) Height and infant mortality ......................................................................... 17
(2) Sexual selection and height .............................................................................. 17
(a) Intrasexual competition ............................................................................. 17
(b) Height and intersexual preferences ................................................................ 18
(3) Does height influence reproductive success? .......................................................... 20
(a) Female height and reproductive output ........................................................... 20
(b) Male height and reproductive output .............................................................. 22
(c) Intralocus sexual conflict over height .............................................................. 24
(4) Is height a target of selection? ........................................................................... 24
VII. Conclusions ..................................................................................................... 25
VIII. Acknowledgements ............................................................................................. 25
IX. References ....................................................................................................... 25
‘Man alone has become a biped; and we can, I think,
partly see how he has come to assume his erect attitude,
which forms one of his most conspicuous characters’
∼ Charles Darwin (1871)
I. INTRODUCTION
The shortest adult in recorded history is Chandra
Bahadur Dangi, a 73-year old Nepalese man, who stands
only 55 cm high. This makes him approximately the
size of one of Robert Wadlow’s feet, the tallest person
ever to have lived. Wadlow reached a height of 2 m
72 cm, and was (allegedly) still growing at the time of
his death, aged 22 (www.guinnessworldrecords.com).
These extremes in height are clearly the result of
pathological growth conditions, but natural variation in
stature is almost as impressive: the Efe hunter-gatherers
of the Congo, for example, barely reach 150 cm on average,
whereas the Dutch are, on average, 35 cm taller,
reaching an astounding 185 cm. Even within populations,
substantial variation exists: the heights of the
shortest 5% and tallest 5% of Dutch people also differ
by approximately 30 cm (McEvoy & Visscher, 2009). Not
surprisingly, height is one of the first things we notice
about our fellow humans; indeed, as an upright walking
mammal, height may be our most conspicuous feature.
Information on height within and between human
populations is readily at our disposal because height is
such an easy trait to study, being both quick and simple
to measure accurately. More importantly, height is
a trait of great biological significance: it is highly informative
about growth rates, life-history trajectories, and
health status at both the individual and population levels.
Indeed, it is so reliable in this respect that it can be
used as a proxy for social and economic conditions. It is
perhaps no coincidence, then, that height has also been
shown to have strong psychological influences on our
behaviour, affecting perceptions of attractiveness, dominance
and power, as well as influencing our choice of
mates. For those interested in an evolutionary approach
to human biology and behaviour, this wealth of information
means that height is an excellent trait to study; one
that lends itself to an integrative analysis, and where we
can potentially measure natural selection in action.
In what follows, we attempt a comprehensive overview
of studies of human height in evolutionary perspective:
its variation across space and time, both historically
and phylogenetically, aspects of its development,
how environmental and genetic resources influence the
patterns seen, how height relates to human life history
and, finally, its influence on reproductive success. Our
aim is not only to illustrate the value of an evolutionary
perspective, but also to attempt an answer to the question:
is height a trait with current adaptive value, or is
height merely the incidental outcome of other processes
more directly related to survival and reproduction? A
greater understanding of the evolutionary significance
of height is not only interesting in itself but, because of
the interplay of economic, environmental and societal
factors with biological factors (e.g. Hatton, 2013), it also
helps to illustrate how culture is integral to any analysis
of human behaviour from an evolutionary perspective.
II. VARIATION IN HUMAN HEIGHT
(1) Spatial variation in body size and height
Over the course of evolutionary history, humans have
colonized almost every habitat, facing a variety of ecological
stressors. The striking variation in body size and
height across human populations has led researchers to
ask whether this represents an adaptive response to environmental
conditions, with thermal stress identified as
a key influence (see Fig. 1 for the global distribution of
female height). That is, humans are thought to conform
to Bergmann’s rule (body size increases with decreasing
mean temperature, which produces a smaller surface
area:volume ratio and so conserves heat) in much the
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
Evolution and human height 3
Fig. 1. Average female height across the world. Data vary with respect to the age at which height was measured and the sample
year. Consequently, the map should be considered as merely illustrative of general patterns of height, rather than definitive.
Colours indicate average height per 2-cm bin. Map drawn using Natural Earth (naturalearthdata.com) and ArcGIS
10.1. SP1, ESRL, Redlands, CA, USA. Data sources: The Demographic and Health Surveys (http://dhsprogram.com/;
DHS data access: http://www.statcompiler.com/; average female height for women between ages 30 and 35 at the last
sampling round); http://en.wikipedia.org/wiki/Template:Average_height_around_the_world (sources provided in link);
Gustafsson & Lindenfors (2004).
same way as other homeotherms [Bergmann, 1847; but
see Geist (1987), who argues that Bergmann’s rule is
invalid, and that body size differences actually reflect the
manner in which the growing season influences energy
availability during growth]. Body size can be interpreted
in a number of ways, of course, and need not refer to
stature alone. Indeed, studies of Bergmann’s rule have
used a variety of measures, including body mass, surface
area:volume ratio, body mass index (BMI), biiliac
breadth (the distance between the protruberances of
the hip bones on either side of the abdomen) and
ponderal index (body mass divided by the cube of
height). Studies also vary in whether temperature or
latitude is used as the climatic variable of interest. Most
studies show at least some support for Bergmann’s rule,
although results are mixed and effect sizes tend to be
moderate at best (e.g. Schreider, 1950; Roberts, 1953,
1978; Ruff, 1991, 1993, 1994; Katzmarzyk & Leonard,
1998; Gustafsson & Lindenfors, 2009; Foster & Collard,
2013; Hadley & Hruschka, 2014). Furthermore, the
most recent, and the most well-controlled, study demonstrated
that Bergmann’s rule holds only for humans in
the Northern hemisphere, and not the south (Foster
& Collard, 2013). Habitable regions of the Southern
hemisphere arguably do not cover a sufficiently large
temperature range to allow thermoregulation-related
natural selection to exert a dominant influence on
human body size.
With respect to height specifically, the classic study by
Roberts (1953) found a significant correlation between
mean annual temperature and height, but also showed
that this relationship disappeared when controlling
for body mass. Similarly, Ruff (1994) found that the
relationship between stature and latitude, as well as
latitude and mass, became non-significant when body
breadth was taken into account (indexed by biiliac
breadth). By contrast, the relationship between biiliac
breadth and latitude remained significant when stature
and mass were controlled. Ruff (1994) concluded that
body breadth, rather than height, was the variable under
climatic selection (as breadth will always affect the
surface area: volume ratio, whereas height would not:
see also Ruff, 1993, 2002).
As Gustafsson & Lindenfors (2009) point out, neither
Roberts (1953) nor Ruff (1994) controlled for potential
collinearity between the morphological variables used
in their studies, nor did they correct for shared ancestry
among their samples. When correcting for these factors,
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4 Gert Stulp and Louise Barrett
and using a larger sample, Gustafsson & Lindenfors
(2009) found a significant, albeit weak, relationship
between latitude and height for both sexes, and they
also tested for a curvilinear relationship, finding a peak
in stature at around 40∘ latitude from the equator. This
was suggested to reflect higher standards of living, and
hence nutritional influences on height, in these regions.
The relationship between height and latitude may also
reflect the fact that humans tend to conform to Allen’s
rule (Allen, 1877), which states that body shape and
proportions vary by minimizing exposed surface area
in relation to decreasing mean temperature (to reduce
surface area: volume ratio, and so conserve heat) and
maximizing exposed surface area with increasing mean
temperature (increasing surface:volume and so improving
heat dissipation). Roberts (1978), for example,
showed that men from populations living in warmer
regions tended to have longer limbs than those living in
colder areas, while Katzmarzyk & Leonard (1998) found
that relative sitting height was negatively correlated with
temperature in both sexes, indicating that more tropical
populations have a more linear body build.
Taken together, these studies provide some evidence
to suggest that spatial variation in height across populations
reflects past selection on morphology in relation
to climatic factors, although as noted, results are mixed.
This is not surprising given that the relationship is complicated
by the fact that humans use unique forms of
behavioural thermoregulation, like clothing and shelter,
to deal with climatic stress (Gustafsson & Lindenfors,
2009), as well as the influence of other ecological
and nutritional factors that affect body size and stature
(Ruff, 1994, 2002; and see Section II.2b).
(2) Temporal variation in height
(a) The ups and downs of human height evolution
Changes in height and limb proportions also characterize
the deep history of the human species, with a general
consensus that early Homo species, in particular H.
erectus (∼1.9 to 0.9Mya), were approximately one-third
larger, with more human-like limb proportions, than the
earlier, more ape-like australopithecine species (∼4 to
1.8 Mya) (Pontzer, 2012). These changes in body proportions
and stature, along with an increase in brain
size, are argued to reflect a shift in ecological niche
in response to climatic change. Unlike the australopithecines,
which subsisted primarily on plant foods, early
Homo is considered to have been an active scavenger and
possibly a persistence hunter of animal prey, i.e. activities
that made more intense locomotor and cognitive
demands, selecting for longer legs and a fully bipedal
posture (Bramble & Lieberman, 2004). Ruff (1993) also
suggests that a taller, more linear frame would be selectively
advantageous with respect to thermoregulation,
which fits with the evidence from contemporary populations
described above.
Early estimates made from the almost complete skeleton
of a young H. erectus male, known as ‘the Nariokotome
boy’, suggested a very tall adult height of 1.85 m
(Ruff & Walker, 1993). Recently, however, Graves et al.
(2010) have argued that this value should be revised
downwards to around 1.52–1.79 m, based on a reassessment
of the life-history trajectory of H. erectus. This is
in line with other findings of early Homo in Dmanisi,
Georgia, where stature has been estimated at 1.56 m
(Lordkipanidze et al., 2007), and the recent analysis of
a complete female H. erectus pelvis from Ethiopia, dated
to between 1.4 and 0.9 Mya, which suggests a standing
height of 1.2–1.4 m (Simpson et al., 2008). On the one
hand, these values suggest variation in height comparable
to that seen within and between modern human
populations. On the other, they may indicate methodological
problems: the accuracy of the new estimates
has been disputed, for example, and the species designation
of the female pelvis has been questioned (Ruff,
2010). Nonetheless, even if the revised heights are confirmed,
it remains the case that H. erectus stood taller
than the australopithecines, with most authors agreeing
that taller stature marks the appearance of early Homo in
the fossil record (Graves et al., 2010; Antón & Snodgrass,
2012).
Further large increases in body size, stature and brain
size are seen among Middle Pleistocene Homo [780000
to 138000 years before present (BP)] in Africa and, as
with the emergence of early Homo, are thought to reflect
the impact of climatic factors on foraging strategies.
Specifically, environmental changes increased the abundance
of ungulate prey, which required a shift to more
organized hunting and greater terrestrial mobility in
order to capitalize on this food source. There is evidence
to suggest that Homo species not only increased the size
of their home ranges, both annually and seasonally, but
also made their first movements beyond the African continent
at this time (Gallagher, 2013). These ecological
changes are linked to an increase in stature among the
fossils of this era. Homo antecessor, from North-Central
Spain, for example, is estimated to have stood around
1.73 m tall, close to mid-20th century European males
(Gallagher, 2013). More generally, Gallagher (2013)
gives values of between 1.50 and 1.90 m for early to late
middle Pleistocene Homo species (Homo heidelbergensis
and Homo rhodesiensis), and Graves et al. (2010) provide
similar estimates. Values at the upper end of this range
therefore exceed those of most contemporary human
populations (Gallagher, 2013). Tall stature is also a feature
of anatomically modern humans, Homo sapiens,
from the Early Upper Palaeolithic (38000 to 22000 BP)
in Europe. Heights are estimated to be 1.74 m for males,
and 1.59 m for females (Gallagher, 2013). It is also worth
noting that this trend of increasing stature did not occur
gradually over the course of the previous 2 million years
of human evolution but, as with brain size, was characterized
by brief bursts during particular time periods
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Evolution and human height 5
and geographic locations; periods that coincided with
marked shifts in both ecology and behaviour, as documented
in the archaeological record (Gallagher, 2013).
This pattern is also true for the decline in stature that
is seen during the Late Upper Palaeolithic (18000 to
9800 BP). Male height dropped by approximately 10 cm
during this period, to an average of 1.64 m. Indeed,
tall males (i.e. those with heights exceeding 1.80 m)
more or less disappear from the fossil record at this
time (Gallagher, 2013). This decline in height has been
tied to the rise in agriculture (Larsen, 1995; Mummert
et al., 2011). Across 14 populations distributed worldwide,
Mummert et al. (2011) found that a shift to agriculture
resulted in a decline in height, regardless of the
temporal period in which agriculture was adopted. The
reasons why this should be are many and varied: agriculture
results in greater variability in food availability
across the year, with periods of poor nutrition—‘hungry
seasons’—experienced regularly while the next season’s
crop grows. Agricultural societies are also more vulnerable
to events that result in periods of poor nutrition,
such as crop failure, compared to other forms of subsistence.
Finally, agricultural societies are associated with
increased population density and hence higher rates of
infectious disease, which is known to have a negative
influence on height (Mummert et al., 2011).
From this, it is apparent that Pleistocene and early
Palaeolithic Homo were not only taller than early Homo
species, but were taller than both medieval and many
contemporary human populations (Ruff, Trinkaus &
Holliday, 1997; Mummert et al., 2011; Gallagher, 2013).
The secular trend of increasing height over the last
century (see Section II.2b) must therefore be placed
in the context of these broader evolutionary and historical
patterns of human height variation. Although
our immediate medieval ancestors were much shorter
than many contemporary humans, this is not true of
our more distant relatives, and the heights reached
by some contemporary human populations are not,
therefore, unprecedented in the history of our species.
This suggests that some modern populations have yet
to reach the upper limit of human height potential.
(b) The modern secular trend in height
Evidence from modern populations reveals quite clearly
how humans have recovered from the ‘agricultural low’
in height, and are moving back toward those reached
by Palaeolithic populations. The process by which
entire populations undergo a change in mean size or
shape across generations is known as a secular trend.
The trend toward increasing height, which began in
the middle of the last century, is found across the
globe, and observed in both developed and developing
countries, although the onset of the trend may vary
(Hauspie, Vercauteren & Susanne, 1996, 1997; Cole,
2000, 2003; Hatton, 2013). Almost all of this increase
is established in childhood, and some argue this is
due to an increase in leg length. Tanner et al. (1982),
for example, demonstrated that most of the secular
increase in height observed in a Japanese sample could
be attributed to increased leg length, and Malina et al.
(2004) found that 60% of the secular height increase in
both boys and girls could be attributed to longer legs in
a population from rural Oaxaca, Mexico. Cole (2000,
2003) has argued, on the basis of the Japanese data, that
secular changes in height have their genesis during the
first 2 years of life: Japanese children aged 2 were 4 cm
taller in 1990 than in 1950, and the same height difference
was true for young adults, which suggests that the
adult trend in height is already in place during the very
earliest phase of childhood. As this is the period during
which stunting manifests under poor environmental
conditions, Cole (2000) argues that the secular height
trend can, in effect, be viewed as a reduction in the
degree of stunting. The secular change in height has
also been accompanied by a secular increase in the
tempo of growth, such that full adult height is reached
at an earlier age: Hauspie et al. (1996) report that most
European males now reach their full height at 18 years
compared to 26 years in the early 1900s.
An increased standard of living as an explanation
for these patterns is well supported by the strong correlation
between increases in height and increases in
gross national product (Floud et al., 2011), child survival
(Bozzoli, Deaton & Quintana-Domeque, 2009),
and life expectancy (Steckel, 2002a,b) within a population.
This in turn reflects several important changes
in public health, including an understanding of the
germ theory of disease, increased personal hygiene, better
health care for children, including vaccinations, and
improved diet (Steckel, 1995, 2009). Indeed, the secular
trend in height is so reliable that increases in height are
widely used by historians and economists as a proxy for
a nation’s development and welfare levels (Floud et al.,
2011). This approach should be used with caution, however,
as it does not seem to apply to all African height
trends (Deaton, 2007; Steckel, 2009).
Although economic prosperity and stability are
undoubtedly important factors in cross-country comparisons,
they cannot account for the major height
differences that exist between populations of equivalent
wealth. The people of the Netherlands provide
a particularly noteworthy example in this respect. In
1860, the average height for Dutch (military) men
was 165 cm, which was lower than many other Western
populations. From the 18th to the early 20th century,
for instance, men from the US ranked number one
in terms of average height (Komlos & Baur, 2004),
towering over the Dutch by around 5–8 cm. One hundred
and fifty years later, Dutch men now rank as the
tallest in the world, with an average height near 185 cm;
an increase of 20 cm. This increase is echoed across
the whole of Western Europe, albeit less dramatically;
Hatton (2013) documents an increase of 11 cm in
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6 Gert Stulp and Louise Barrett
male height from the 1850s to 1980, although there is
wide variation across different countries. This increase
in stature has been continuous and regular, with the
exception of the periods covered by the two World Wars
(Liestøl & Rosenberg, 1995; Silventoinen, 2003). By
contrast, the heights of US males have increased by only
6 cm during this same period (Komlos & Baur, 2004).
Economic prosperity is not sufficient to explain the
height discrepancy between the Dutch and the North
Americans because the latter actually have a higher per
capita income, invest more in health care, and have a
similar caloric intake to the Dutch. Part of the difference
in average height can, however, be attributed to
differences in social equality: despite its higher per capita
income, social inequality is much higher in the USA
than in the Netherlands, and the health care system is
not equally accessible to everyone. Greater equality in
access to resources increases the average height of a
population because the greater increases in height by
the poor can counterbalance, or even outweigh, the
stagnation in height of the wealthy (i.e. there are diminishing
returns on height with increasing wealth) (Blum,
2013). Put differently, a much smaller fraction of the
population is exposed to environmental influences
that can result in stunting and reduced adult height
when resources are more equitably distributed across
socio-economic strata, thus pushing up the average
height of the population as a whole.
Equivalent differences also exist for countries that lie
in much closer proximity. Although in most Northern
European countries, the secular trend in height has
been slowed or stopped (Hauspie et al., 1997; Garcia &
Quintana-Domeque, 2007), the Dutch, apparently not
yet tall enough, keep on growing (or, at least, have yet
to show any sign that the trend is slowing down: Fredriks
et al., 2000; Danubio & Sanna, 2008; but see Schönbeck
et al. 2012). The reasons for Dutch superiority in height
have been related to subtle variations in nutrition and
health care. Social welfare, the medical system and universal
health care are all of a very high standard in
the Netherlands, and Dutch mothers are also known
to make good use of the health care system (de Beer,
2004), all of which are likely to have substantial consequences
for stature. It has also been suggested that
the type and quality of food eaten by the Dutch may
give them an anthropometric advantage: the Dutch consume
a high proportion of dairy products, particularly
milk (Fredriks et al., 2000; de Beer, 2012). Similarly, the
striking secular trend in height among the Japanese has
been attributed to an increase in milk-drinking following
the second World War (Takahashi, 1984). Thus, subtle
variations in health care and nutrition between countries,
which are not caught under the umbrella of general
economic prosperity, probably account for much of
the variation in height that exists between populations.
These shifts in average height over historical time in
relation to resource availability also have implications
for tests of evolutionary hypotheses concerning spatial
variation in body size, such as Bergmann’s rule
described above. Katzmarzyk & Leonard (1998), for
example, replicated the findings of Roberts (1953)
study on body size and latitude, conducted 40 years previously,
but found a much weaker relationship. As their
study was also able to demonstrate a secular trend in
body size among the Southern populations in their sample,
Katzmarzyk & Leonard (1998) therefore suggested
that improved nutrition, and hence increased average
body size among these populations, could account for
the weaker relationships found. This in turn suggests
that at least some of the variation attributed to evolved
differences in response to climate may actually reflect a
developmental response to nutritional stress.
III. DEVELOPMENT OF HEIGHT AND SEXUAL
DIMORPHISM
(1) Height across development
Having considered height variation in both time and
space, it now becomes pertinent to consider growth
patterns across development, given that shifts in growth
rates and developmental timing are the mechanism by
which evolutionary and historical changes in height are
produced. An understanding of how height differences
emerge during ontogeny also provides the background
for exploring patterns of sexual dimorphism in height.
In what follows, we draw mainly on Bogin’s (1999b)
comprehensive review of human growth, and interested
readers can follow up in more detail by referring to
this work, as well as Tanner (1962, 1990), or the more
concise summaries found in Bogin (1999a, 2010).
One of the most prominent differences in the human
growth curve compared to other mammals is that
humans achieve their maximal rate of growth (in terms
of both length and mass) during gestation, and growth
rates then decelerate during infancy relative to other
mammalian species. One reason why this should be is
that humans generally carry only a single fetus, rather
than a litter, which means faster rates of growth are possible
during gestation (Bogin, 1999a, 2010). Once born,
however, growth and maturation proceed much more
slowly, with puberty and sexual maturation delayed by
many years. This is true not only in relation to most
other mammals, where sexual maturity is reached soon
after weaning, but also in relation to other primate
species. All primates show a significant juvenile growth
period. In humans, however, this period is greatly prolonged
(Bogin, 1999a, 2010; Leigh, 2001).
Puberty in humans is reached at the point when
growth rates are at their lowest since birth. The adolescent
growth spurt, considered to be a unique characteristic
of human growth, is thus triggered by the
hormonal changes that occur at puberty. This happens
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Evolution and human height 7
in both males and females, and is generally found in
all human populations (Bogin & Smith, 1996; Bogin,
1999a; Gluckman & Hanson, 2006; but see below for
some possible exceptions). Whereas other primates,
like rhesus macaques (Macaca mulatta), show a brief
increase in growth velocity at or around sexual maturity
and sometimes continue to grow subsequently, humans
experience a single, absolutely large and unambiguous
growth spurt that follows the onset of puberty. In addition,
the human adolescent growth spurt lasts for years,
rather than months. Humans also differ by showing a
more distinct sex difference in the expression of the
adolescent growth spurt (Bogin, 1999a): women both
start and stop their growth spurt at an earlier age than
men, thus reaching their final height sooner. Indeed,
many of the sex differences seen in adult body size
and shape arise as a consequence of these differential
growth patterns at adolescence (Tanner, 1962, 1990).
Both the later occurrence of the male spurt, allowing an
extra period of growth for boys, and the greater intensity
of the spurt itself, results in higher levels of sexual
size dimorphism in adulthood compared to earlier
life-history stages (Tanner, 1962; Bogin, 1999a).
As the above description highlights, growth ontogeny
is not a smooth progression through time, but is
inherently dynamic, proceeding in a series of spurts
(basically, changes in growth velocity). The timing
and patterning of these spurts in humans – during
gestation, middle childhood (around 6 years) and during
adolescence – differs markedly from most other
mammals, including other species of primate (Bogin
& Smith, 1996; Bogin, 2010). The variable patterns of
growth seen across species, in both the number and
timing of growth spurts, has led to the suggestion that
such spurts, by virtue of their modular nature, are
highly evolvable features of ontogeny; the placement
and timing of growth spurts across development may
thus reflect the outcome of natural (and potentially
sexual) selection (Bogin, 1999a).
It should also be apparent that factors that exert
an influence on height, like periods of nutritional
stress or the incidence of infectious disease, will do
so to a greater or lesser extent depending on their
timing in relation to the human growth cycle. Adult
stature in 18th and 19th century America and Europe,
for example, was strongly associated with economic
factors, like grain prices, with the lag observed between
cycles suggesting that poor economic conditions during
the early growth phase exerted the most significant
influence on adult stature (Woitek, 2003). This effect
was argued to be cumulative because of the way in which
subsequent economic cycles mapped onto the human
growth cycle: children born during a recession would
experience subsequent economic downturns during
both the middle childhood growth phase and again
during the adolescent growth spurt, compounding the
effects of poor growth during infancy (Woitek, 2003). It
seems possible that patterns like these, which illustrate
the sensitivity of growth to economic conditions, can
also shed light on inter-population height differences in
the present day: lower economic stability in general, and
hence larger fluctuations in economic conditions over
time, may explain both the finding that populations
in developing nations tend to be shorter than those
in the developed world, and that variation in height
across social classes is known to be greater in poorer
countries (Silventoinen, 2003; Deaton, 2007), but much
reduced where standards of living are higher (Garcia &
Quintana-Domeque, 2007). Such findings may also help
explain the negative secular trends in height seen in
some parts of Africa, India and South America (Malina,
2004).
If, as Cole (2000) suggests, we can view secular height
trends as a reduction in stunting, it should follow that
understanding the causes of stunting will also shed light
on patterns of increased growth across time. This is
aided by the fact that, as Walker et al. (2006) point out,
most bioanthropological studies of human growth have
focused on the impact of constraints on growth, with
an emphasis on the effects of nutrition. Indeed, lack of
nutrition, particularly protein deficiency, is recognized
as one of the main contributors to reduced infant
growth in developing countries, and supplementary
food programs have been shown to produce clear
improvements in growth rates and reduced stunting
(Edozien, Khan & Waslien, 1976; Beaton & Ghassemi,
1982; Silventoinen, 2003). Due to the strong association
between growth and nutrition, both UNICEF and the
World Health Organization collect growth data as a
means to assess the success of its supplementary food
programs and to establish indicators of malnutrition
(De Onis et al., 1993; Steckel, 1995). The positive effects
of supplemental feeding are obviously not restricted to
developing nations, however; experiments conducted
as long ago as 1928 showed that the provision of
extra milk increased the growth of schoolchildren in
the UK (Orr, 1928; Leighton & Clark, 1929). Indeed,
even in contemporary populations, drinking milk can
substantially increase height (de Beer, 2012).
In addition to, and intertwined with, the effects of malnutrition,
childhood disease is known to adversely affect
growth: mounting an immune response to fight infection
increases metabolic requirements and can thus
affect net nutrition, and hence productivity. Disease
also prevents food intake, impairs nutrient absorption,
and causes nutrient loss (Silventoinen, 2003). Accordingly,
recurrent infection is associated with a lower
height-for-age (Dowd, Zajacova & Aiello, 2009). Adverse
economic and social conditions in childhood, such as
psychosocial stress, housing conditions and physically
strenuous work, also lead to short stature in adulthood
(Mascie-Taylor, 1991; Peck & Lundberg, 1995; Cavelaars
et al., 2000). Family size can also be a risk factor
(Rona, Swan & Altman, 1978; Lawson & Mace,
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8 Gert Stulp and Louise Barrett
2008): the presence of (many) siblings, for instance,
significantly reduces an individual’s height (presumably
because finite resources have to be distributed across all
children, which leads to both reduced nutrient intake
and increased psychosocial stress) (see also Hatton &
Martin, 2010). Even in a wealthy, well-nourished population
like the UK, and adjusting for family-level socioeconomic
factors, those raised with four siblings are, on
average, 3 cm shorter than those born without siblings
(Lawson & Mace, 2008). Perhaps the best illustration of
the dramatic plasticity in growth, however, comes from
studies comparing the offspring born to those who emigrated
to more affluent populations with those remaining
in their less-affluent native population (Kim, 1982;
Bogin et al., 2002). Maya children born in the USA,
for instance, are over 10 cm taller than Maya children
born in Guatemala (Bogin et al., 2002). Many of the
above patterns, including the secular trend in height
and height differences between individuals and populations,
have also been attributed to differences in microbial
transmission (Beard & Blaser, 2002). Interactions
with microbes influence not only levels of infection, but
also affect the colonization of the gastrointestinal tract
by microbes that assist with digestion (the microbiota),
both of which may act to reduce adult height.
(2) Why grow up, rather than out?
Growing taller over the course of childhood is something
we take entirely for granted; we simply accept
that adults are taller than children. One can, however,
pose the question as Ellison (2009) does: why do we
grow up, rather than out? That is, why is metabolic
effort expended on skeletal development, rather than
increasing body mass, whether by storing fat or building
muscle? Given the costs of reproduction, for females
in particular, larger body mass would seem more advantageous
than taller stature. Yet, skeletal growth, which
occurs mainly in the long bones of the limbs, followed
secondarily by the spine, pelvis and skull, is more tightly
canalized than increases in body mass, and is highly
buffered against short to medium term variation in energetic
conditions (Bogin, 1999b). In addition, skeletal
growth is much less plastic than growth in body mass:
although bone can be resorbed, and the skeleton provides
an important reservoir of minerals like calcium,
this process does not cause the long bones to shrink as
a consequence (Ellison, 2009). Overall then, as Ellison
(2009) notes, height is given much greater metabolic
priority than mass: our physiology seems designed to sacrifice
growth in mass to preserve growth in height (at
least in the short to medium term).
One plausible explanation for why this occurs is
linked to the allied process of reproductive maturation:
menarche in girls usually occurs shortly after the peak
of the adolescent growth spurt has been passed, which
is not too surprising given that both are influenced
by steroid hormones (Tanner, 1981; Ellison, 1990).
Increased production of oestrogen slows the process of
growth, and eventually causes it to cease, by stimulating
mineral deposition in the growth plates at the ends of
the long bones, thus terminating cell proliferation, and
resulting in the fusion of the growth plates to the shaft of
the bone. Increases in oestrogen also lead to the onset
of menstrual bleeding. Thus, the change in hormonal
profile that results in the slowing and eventual cessation
of growth during the period from late teens to early
adulthood is the same as that which results in the onset
of sexual maturity. This suggests that skeletal maturity
is, in some way, key to females’ ability to reproduce
successfully.
Ellison (2009) argues that it is not height per se that is
crucial, but the fact that height indexes another aspect
of skeletal size: namely, pelvic width. The size of the
pelvic canal imposes an absolute mechanical constraint
on the ability to give birth successfully among all primates,
but this constraint is particularly pressing in
humans due to the antagonistic selection pressures that
give rise to the so-called ‘obstetric dilemma’: a widely
accepted hypothesis is that selection for increased brain
size, which served to increase the size of the neonate’s
head at birth, was countered by earlier selection for
efficient bipedal locomotion. This re-shaped the pelvis
and so narrowed the birth-canal, resulting in a situation
where, relative to other primate species, a much
larger-brained infant was now required to exit through
a much narrower opening (e.g. Wittman & Wall, 2007).
Although there has been selection on pelvic width
and shape independently of height in females (particularly
so in some small-statured populations: Kurki,
2007, 2011, 2013) this has been limited by the costs in
terms of effective locomotion, with the result that height
constrains reproductive functioning: females have to
achieve a certain level of skeletal height because, to a
large extent, they rely on the correlated growth of the
pelvis to reach a width that is sufficient for the passage
of an infant, without adversely affecting locomotion. A
biiliac breadth of around 24–25 cm seems to be a good
approximation of this ‘pelvic size threshold.’ The age
at which this threshold is reached correlates strongly
with age at menarche (Ellison, 1982, 1990, 2009). This,
then, may help explain why skeletal growth is prioritized
over adding muscle mass or storing fat: until the
pelvis reaches a size at which birth is possible, there is
no point to storing energy for future reproduction (Ellison,
1990, 2009). Gluckman & Hanson (2006) further
suggest that there may have been positive selection on
female height in the hominin line: larger brained offspring
would require a wider pelvic canal, which would
lead to selection for prolonged skeletal growth to attain
the pelvic size threshold required, and hence to taller
stature.
In line with this, it is well established that, across
contemporary human populations, taller women experience
fewer problems during labour and birth, and
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Evolution and human height 9
have a lower mortality risk (Wells, DeSilva & Stock,
2012), because of a lower risk of a mismatch between
fetal head size and the size of the birth canal; the ‘obstetric
dilemma’ referred to above. It is also important to
realize, however, as Wells et al. (2012) demonstrate,
that the dangers posed by the obstetric dilemma are
not fixed, as is often supposed, but tend to shift over
both time and space, reflecting phenotypic plasticity
in maternal pelvic dimensions and, to a lesser degree,
infant growth patterns. Changes in stature are therefore
critical in this regard, as height is a trait that is
sensitive to environmental conditions and, as we’ve
noted, changes in stature and body proportions affect
the dimensions of the pelvis. The pelvic size threshold
should therefore be seen as the absolute minimum
size at which birth becomes possible, and not as an
optimum. Accordingly, factors like variation in thermal
stress have been linked to the obstetric dilemma (Ruff,
1994). Under high thermal stress, where taller, narrower
bodies are favoured, the obstetric dilemma may
be exacerbated relative to less-stressed populations,
especially as fetal mass contributes directly to maternal
endogenous heat production, further increasing
the pressure to retain a body size and shape that can
effectively dissipate heat (Ruff, 1994; Wells et al., 2012).
Reductions in nutritional status and the impact of
infectious disease, both of which lead to smaller body
size, can also be expected to increase the obstetric
dilemma by reducing pelvic dimensions, and in the case
of certain diseases of malnutrition, like rickets, by altering
pelvic shape in ways that can impede birth (Wells
et al., 2012). Given that such reductions in stature characterize
the shift to agriculture discussed above, it is thus
possible that some of the increased mortality associated
with this period reflects an intensification of the obstetric
dilemma (Wells et al., 2012). By the same token,
recent secular trends in height across the developed
world may have acted to alleviate it to some degree. This
observation is, of course, complicated by technological
interventions that can also reduce the impact of birth
complications. We revisit the impact of stature on birth
complications below, when we consider the extent and
nature of current selection pressures on height.
Obviously, the pelvic size hypothesis does not apply to
males but, equally obviously, boys also continue to grow
for many years before reaching sexual maturity. In the
case of males, skeletal growth is linked to increases in
muscle mass and shoulder breadth at puberty, and Ellison
(2009) speculates this may relate to male reproductive
strategies in some way. Gluckman & Hanson (2006),
for example, suggest that taller males would be stronger
and hence more dominant, and may have been more
strongly favoured as mates. If this kind of process did
operate, then it may have pulled female height along in
its wake (as the same genes operate in both sexes), thus
amplifying the direct influence of natural selection on
female height.
(3) Sexual dimorphism in height
Sexual dimorphism in body size is often taken as evidence
for sexual selection. Among most mammals,
larger male size often indicates competition by males
for access to females (e.g. Fairbairn, Blanckenhorn
& Székely, 2007). Larger males experience greater
success in competing against other males, and hence
achieve higher fitness, which then leads to pronounced
sexual dimorphism in size. The moderate degree of
sexual dimorphism seen in humans (males are approximately
15% heavier and 9% taller than females on
average) has been attributed to a history of mild polygyny
and inter-male competition, as well as a variety
of other factors (all of which remain under debate,
with no consensus reached), including high levels of
egalitarianism, phylogenetic inertia, and sex-biased
parental investment.
Examining sexual dimorphism in deep evolutionary
time, it is notable that changes in height among Homo
species are accompanied by a decrease in sexual dimorphism
(Frayer & Wolpoff, 1985). Gray (2013) notes that
Australopithecus afarensis (4 to 3 Mya) males are believed
to be around 44% bigger than females, whereas this
figure is 26% for Homo habilis (2.4 to 1.6 Mya), 13%
for Homo erectus (1.7 to 0.7 Mya), and a very moderate
9% for modern humans. European Upper Palaeolithic
populations also show more body dimorphism than
later Holocene populations, but they are less dimorphic
than Middle Pleistocene populations (Frayer & Wolpoff,
1985). Frayer (1980, 1981) has suggested that the ‘gracilization’
of males reflects changes in prey assemblages,
which became both smaller and less aggressive over
time, and hence required reduced physical size and
robustness to hunt and kill; the kinds of weapons used
to kill prey changed also, with a shift from spears to bow
and arrow, which requires less in terms of upper body
strength (but see Wolfe & Gray, 1982; Holden & Mace,
1999). Gray (2013) adds to this by arguing that the egalitarian
ways of band hunter-gatherers may have been a
force in the reduction of sexual dimorphism.
A decrease in dimorphism has also been argued
to reflect the shift to agriculture, where it indicates
changes in the division of labour, with each sex
engaging in more similar kinds of economic chores
compared to hunting and gathering (Frayer, 1980).
Ruff (1987), for example, documents a decline in the
sexual dimorphism of the femur and tibia from the
Middle Palaeolithic toward the present day, which is
suggested to reflect a change to more similar mobility
levels between males and females. A meta-analysis of five
North American populations by Vick (2005), however,
found no evidence of a significant decline in dimorphism
during the agricultural transition. The idea
that sexual dimorphism arises as a result of selection
acting differentially on sex-specific ecological strategies
among contemporary humans is also raised by several
other authors (Brace & Ryan, 1980; Wolfe & Patrick
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10 Gert Stulp and Louise Barrett
Gray, 1982; Shine, 1991; Holden & Mace, 1999; but
see Harvey & Bennett, 1985). Thus, changes in human
body size and stature over evolutionary time, both in
absolute terms, and relatively between the sexes, may
reflect changes in ecological characteristics, including
the increasing interplay of biological and cultural
influences, and not only aspects of sexual selection.
With this caveat in place, we can consider the evidence
for sexual selection as the cause of sexual dimorphism.
One of the earliest studies applying sexual selection theory
to human populations is by Alexander et al. (1979).
After establishing that sexual size dimorphism (SSD)
was positively correlated to the degree of polygyny in
pinnipeds, ungulates, and primates, the authors presented
evidence to suggest that, among humans, populations
with polygynous mating systems displayed higher
levels of SSD than those with monogamous systems (but
only where such monogamy was not socially imposed).
These results are, however, widely disputed. Gray &
Wolfe (1980), in particular, highlighted severe methodological
problems with the Alexander et al. (1979) study
(including issues relating to data selection, marriage system
attribution, and height measurements), and their
reanalysis suggested that polygyny was not related to
SSD, but that dietary factors exerted a strong influence
on sex differences in stature across populations. Nutritional
deficiencies have a stronger effect on male than
on female growth, which could account for the observation
that well-nourished populations are more dimorphic
than malnourished ones (Hiernaux, 1968; Brauer,
1982; Hamilton, 1982; but see Guegan, Teriokhin &
Thomas, 2000; Gustafsson et al., 2007). Gaulin & Boster
(1985), in turn, were also skeptical of earlier research
on SSD, arguing that polygyny was not related to cultural
differences in dimorphism, and that cross-cultural
variation was minimal when excluding populations for
which estimates of heights are based on very few individuals.
Ironically, these same authors went on themselves
to study variation in SSD in relation to social stratification
and polygyny (Gaulin & Boster, 1992), which more
or less replicated the findings of Alexander et al. (1979).
Most early work on SSD is, however, severely hampered
by a lack of phylogenetic methods (which, of
course, were not readily available at the time). At least
two studies have demonstrated that both sex differences
in size and the explanatory factors used (e.g. mating
system, division of labour, subsistence strategy) show
a strong phylogenetic signal, which must therefore be
taken into account in statistical analyses (Holden &
Mace, 1999; Gustafsson & Lindenfors, 2004). Holden &
Mace (1999) present just this kind of phylogenetically
controlled analysis (also controlling for geographical
proximity), finding that sexual dimorphism was associated
only with the contribution of women to food
production, and not with subsistence strategy nor marriage
system (although they do note that, because polygyny
is a highly ‘clustered’ trait, its effects are not easily
detected, which means an influence of polygyny cannot
be ruled out). When the sexual division of labour is less
distinct, and women contribute more to the production
of food, sexual dimorphism tends to be lower. Holden &
Mace (1999) argue that, in populations in which women
perform a large proportion of subsistence labour, parents
may bias their investment towards daughters, and
hence lower dimorphism in stature will be expected.
A more recent hypothesis concerns the selection pressure
of maternal death in childbirth: in high-fertility
countries with high maternal mortality, selection should
strongly favour increased female height (as height is
positively associated with ease of the delivery of a child)
and hence reduce SSD (Guegan et al., 2000).
Some authors have also studied whether Rench’s rule
applies to humans. This rule states that, in taxa where
males are larger than females, there is also a positive
correlation between body size and SSD (Fairbairn,
1997). This is generally well established in animals,
although exceptions exist (Abouheif & Fairbairn, 1997).
Thus, one would expect that, in tall human populations,
dimorphism in stature between men and women should
also be greater compared to ‘shorter’ populations. This
prediction does not, however, seem to be met in humans
(Gustafsson & Lindenfors, 2004, 2009; Gustafsson et al.,
2007).
In contrast to the studies described above, Rogers
& Mukherjee (1992) have argued that we should not,
in fact, expect sexual dimorphism to represent an
adaptation to the environment because the response to
selection is likely to be very slow due to the genetic correlation
in stature between the sexes (i.e. the same genes
for height operate in both sexes). It is doubtful whether
there has been sufficient time, and if cultural practices
have been sufficiently stable, for sexual dimorphism
to be attuned to specific population conditions. As
should be apparent from these conflicting theoretical
perspectives, empirical findings, and methodological
criticisms, support for any of the hypotheses explaining
sexual dimorphism is not particularly strong, and all
require further testing. The causes of (human) size
dimorphism are clearly complex and our understanding
of these at present is poor, but it seems likely that
several mechanisms operate both within and between
populations (Plavcan, 2011, 2012).
IV. GENETIC INFLUENCES ON HEIGHT
Although environmental variation is an important factor
influencing adult height, such influences are considered
insufficient to account fully for observed population
differences. Some African populations are considerably
taller than others, for example, despite experiencing
poorer nutrition and elevated levels of pathogen
exposure (Deaton, 2007), suggesting that such differences
may have a genetic basis. To date, very few studies
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Evolution and human height 11
have addressed this issue. Notable exceptions are studies
investigating the difference in height observed between
the Baka pygmies of Cameroon and taller neighbouring
non-Pygmy populations (Becker et al., 2011; Jarvis et al.,
2012). Both of these studies showed that Pygmy individuals
who were genetically more similar to non-Pygmy
individuals (i.e. higher levels of genetic admixture) were
taller. Most recently, Perry et al. (2014) have shown that
the pygmy phenotype likely arose several times independently
due to positive natural selection for short stature.
Additional evidence for genetic factors underlying population
differences in height come from a Korean population
(Cho et al., 2009). Several loci previously identified
in European populations were also detected in
this sample. Most pertinently, one of the genes with
the largest effects on stature observed in Europeans
(HMGA2) was also associated with height in the Korean
population, although its effect was much smaller and
the frequency of the ‘height-raising’ allele in the population
was lower. These findings suggest that genetic
differences may, in part, explain why Koreans are, on
average, shorter than Europeans (Cho et al., 2009).
Although studies investigating genetic differences in
height across populations are still rare, the genetics
of height itself is, of course, a very well-studied
phenomenon. Human height is, perhaps, the classic
example of a quantitative trait under genetic influence;
indeed, the study of stature was essential to the emergence
of fundamental concepts in genetics, with Francis
Galton first demonstrating the statistical relationship
between the heights of parents and their children (Galton,
1886), and establishing its high heritability. These
studies have stood the test of time with ‘twin studies’
consistently demonstrating that the heritability of
height is around 0.80 (Silventoinen et al., 2003b; Perola
et al., 2007; see also Visscher et al., 2006, 2007, which
used the genetic similarity between non-twin siblings to
arrive at a similar value). The heritability estimate for
height therefore seems to be exceptionally reliable: it
has been observed repeatedly across different populations
and using different methods, although its high
value is restricted to more affluent populations. Heritabilities
in developing countries are slightly lower with,
for instance, a value of 0.62 in a Nigerian sample (Luke
et al., 2001), 0.65 in a Chinese sample (Li et al., 2004),
and 0.74 in a Jamaican sample (Luke et al., 2001). Similarly,
with an increased standard of living, heritability
also increases over time within a population (Silventoinen,
Kaprio & Lahelma, 2000). A potential explanation
for these findings is that differences in factors
like food abundance exert a greater influence on differences
in adult height than an individual’s genetic
make-up in poor environments. By contrast, in richer
environments, differences in food abundance are less
severe and, as a consequence, their effects on growth
will be diminished compared to genetic effects (Charmantier
& Garant, 2005).
The high heritability of height does not, however,
mean that environmental influence cannot exert large
effects, but merely that, in populations where environmental
conditions are very similar for most individuals,
most phenotypic variation will be due to genetic differences.
Nonetheless, variation in environmental factors
may affect height substantially, milk consumption being
a very good example of an environmental influence
that exerts large effects on height in environmentally
homogenous populations (de Beer, 2012).
The high heritability of stature should also not be
taken to imply that height is a result of a few genes
that exert large effects. As early as 1918, Sir Ronald
Fisher proposed that a ‘polygenic’ model could explain
variation in height, with many genes, each with a small
effect, influencing stature (Fisher, 1918). Since the
completion of the Human Genome Project in 2003,
scientists have been able to identify the genetic variants
associated with certain traits and diseases by comparing
individual genomes. To date, human genome-wide association
studies (GWAS) have identified 180 loci, which
account for about 10–20% of the observed variation
in height (Allen et al., 2010), and this same genetic
information can be accurately used to identify those
of tall stature within a population (Liu et al., 2013).
Moreover, using sophisticated statistical modelling,
Yang et al. (2010) found that common genetic markers
could explain fully 45% of the variance in height when
all genetic variants were considered simultaneously.
Height is thus a truly polygenic trait, with almost 1%
of all human genes contributing to height variation in
some way (Allen et al., 2010).
One of the great advantages of modern genetic techniques
is that they offer insight into the functional
significance of the genes that regulate height. The
height-associated loci identified by GWAS have been
shown to cluster together in biologically relevant pathways,
including those related to bone formation, chronodocyte
proliferation and differentiation (the cells that
produce and maintain cartilage), and the growth hormone
signalling pathway (Lettre, 2011). In addition,
21 loci have been found to be situated near a skeletal/growth
gene known to be associated with pathological
growth syndromes when mutated, with 13 of these
located within the gene itself (Allen et al., 2010; Lettre,
2011).
There has also been interest in identifying whether
any adult-height-associated loci are implicated in the
growth process, especially as twin studies have suggested
a strong genetic component to growth variation (Silventoinen
et al., 2003b, 2008). The few studies conducted
to date suggest that most adult-height-linked loci are
not, however, associated with children’s height, which
may reflect the highly heterogenous growth patterns
seen among children. Instead, it has been suggested that
height velocity (i.e. growth rates) may represent a more
useful phenotypic trait for studies of this nature (Lettre,
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12 Gert Stulp and Louise Barrett
2011). Again, data testing these ideas are very limited at
present, and so far have not revealed any genetic associations
that reached genome-wide significance (Lettre,
2011). Sovio et al. (2009) have shown, though, that loci
associated with adult height are at least nominally associated
with height velocity during infancy and puberty.
In addition, Widén et al. (2010) found an association
between variants near the LIN28B gene (a gene known
to control developmental progression in Caenorhabditis
elegans: Moss, Lee & Ambros, 1997) and growth
increases between the age of 14 years and adulthood.
This same locus has also been associated with adult
height (Allen et al., 2010) and age at menarche (Elks
et al., 2010), suggesting it has an influence on pubertal
timing. This makes sense given the idea that skeletal
maturity, and in the case of females, pelvic geometry
(Ellison, 1990), are hypothesized to be key to future successful
reproduction. Experiments on mice have shown
that those with a Lin28a transgene show increased body
size and delayed puberty (Zhu et al., 2010), which supports
the pubertal timing interpretation.
Understanding more about genetic influences on
height is not only beginning to reveal how and where
genes exert their effects on the growth process, but
also helps to reinforce the fact (perhaps ironically)
that the secular trend in height must primarily reflect
environmental influences, and is unlikely to be the
consequence of significant genetic change; height
would not be expected to increase so rapidly over such
a short period if this were the case (Deaton, 2007;
McEvoy & Visscher, 2009). To be more precise, if the
Dutch increase in height of 20 cm in the last 150 years
were solely genetic, this would require that, in every
generation, fully 30% of the shortest individuals in the
population must fail to reproduce at all (assuming a
generation time of 25 years and a heritability of 0.8);
a selection pressure high enough to be considered
implausible (Kingsolver et al., 2001). It is worth noting
again, however, that while genes are unlikely to have a
major role in the secular trend in height seen around
the world, their effects cannot and should not be ruled
out entirely. For example, height-increasing alleles are
found to occur at higher frequencies in northern than
in southern Europeans (Turchin et al., 2012), and this
difference is suggested to be a consequence of selection
on gene variants associated with height, rather than
with genetic drift (i.e. changes in gene frequencies that
occur by chance). Thus, adult height differences across
populations of European descent are not driven solely
by environmental differences, but apparently retain a
signature of past differential selection.
V. LIFE HISTORY AND HEIGHT
Having now surveyed patterns of height variation and
their links to environmental and genetic factors, it
is apparent that variation in height is systematically
related to variation in environmental conditions, and
can largely be attributed to developmental plasticity in
growth velocity during childhood, although there is also
some evidence for genetic differences between populations.
There is also good anthropometric evidence for a
link between skeletal maturity and sexual maturity, with
recent genetic evidence in line with such a link. The
energy devoted to growth in childhood and the timing
of the switch from growth to reproduction thus combine
to determine adult height in a population. This raises
the further question of how and why resources are allocated
to growth during development, and the scope and
limits of developmental plasticity in relation to height.
These are issues that can be most productively explored
from a life-historical perspective.
(1) Principles of life-history evolution
Body size at maturity, and the process of growth toward
this size, is an evolutionary dilemma for all species.
At its the heart lies a classic trade-off between growth,
maintenance and reproduction (Stearns, 1992), which
in turn reflects a basic ‘principle of allocation’: energy
and resources can only be invested once, such that
investment in one direction, e.g. towards maintenance,
diverts investment away from the other two components
(Stearns, 2000). The costs of maintenance (e.g.
the metabolic costs of being alive, the materials and
energy needed for tissue maintenance and repair, healing
from injury and general wear and tear, and defence
against disease) can be subtracted from energy intake
to determine the net resources available for growth and
subsequent reproduction once growth is completed,
with the latter known as ‘productivity’ (Charnov, 1991,
1993; Stearns, 1992). It should be obvious that higher
productivity means greater energy available for growth
and/or reproduction. Life-history theory therefore predicts
that, all else being equal, greater capital investment
in body size, i.e. growing larger and maturing later, will
increase adult reproductive capacity; the same may be
true for individuals of increased height.
Allocation of resources, however, also depends on
mortality rates, as these dictate the extent to which
the greater reproductive capacity acquired during the
pre-reproductive growth phase can be translated into
offspring. High levels of adult mortality (especially from
extrinsic causes, e.g. violence or disease) should lead
animals to forego extra growth and mature earlier so
that reproduction can occur at an earlier age. Mortality
during the juvenile phase is also expected to exert
a strong influence on life-history trajectories, as this
determines the likelihood that an individual will actually
survive to reach reproductive age at all; again, higher
rates of extrinsic mortality acting on juveniles should
favour earlier sexual maturity. The incorporation of
mortality rates into life-history theory thus builds in the
opportunity costs of a delay in reproduction, and is thus
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Evolution and human height 13
crucial for setting the balance between growth, reproduction
and hence adult body size across species (Harvey
& Clutton-Brock, 1985; Harvey & Zammuto, 1985;
Promislow & Harvey, 1990; Harvey & Purvis, 1999).
(2) Life-history trade-offs and norms of reaction
Similar trade-offs between growth and reproduction
may also occur within species, including humans, in
response to environmental variability and mortality risk,
generating plasticity in growth trajectories, body size
and the onset of maturity. Systematic variation at this
scale may therefore reflect the operation of evolved
reaction norms for optimal growth (i.e. the set of phenotypes
that result from a single genotype across different
environments: Roff, 1992; Stearns, 1992; Walker et al.,
2006). For example, in a detailed study of small-scale
societies, Walker et al. (2006) found that poor environmental
conditions generally lead to a trade-off between
maintenance and growth (favouring energy invested
in maintenance), resulting in small adult stature, slow
growth rates, and later ages of menarche compared to
higher quality habitats (although when juvenile mortality
risks are high, faster growth rates are favoured: see
Section V.5). This may represent an adaptive response
because it reduces bodily maintenance costs, lowering
both intrinsic mortality risk and increasing the relative
allocation of resources available for reproduction
(Arendt, 1997; Ellison, 2001; Worthman, 2003; Walker
& Hamilton, 2008). Poor growth conditions can thus
serve both as a constraint on growth and as a valid indicator
of the kind of future nutritional regimes an individual
is likely to face, ensuring that individuals attain
the body size best suited to a nutritionally poor environment.
Slow growth spreads nutritional demands over a
longer period of development, and short adult stature
lowers the cost of maintenance across the lifespan, both
of which can represent an adaptive trade-off between
growth and maintenance (Walker et al., 2006) as we discuss
further below (Section V.5). That is, phenotypic
variation across environments may represent the expression
of an evolved reaction norm, which ensures an
appropriate trade-off between life-history components.
(3) Height and sexual maturity in contemporary
industrial populations
Among industrialized nations, females are not only
absolutely taller but they also display earlier menarche
compared to small-scale societies (e.g. Cole, 2000)
(although it should be noted that, under good conditions,
women in small-scale societies can also reach
menarche early and at a larger body size compared to
those in poor conditions, that is, similar patterns can be
seen, even if absolute values differ). A good-quality environment
helps to reduce bodily maintenance costs (e.g.
because fewer immune responses need to be mounted),
leading to increased growth rates and hence earlier
reproductive function. These changes in height and age
at sexual maturity can be seen as the consequence of
sustained good nutrition and low environmental stress,
as discussed above in relation to the secular trend in
height (Section II.2b); hence, the secular trend can be
viewed as the manifestation of an evolved reaction norm
that regulates life-history transitions in ways appropriate
to the environment. A recent meta-analysis by Mcintyre
& Kacerosky (2011), however, demonstrates that the
relationship between height and age at menarche may
have reversed in industrialized nations: taller heights are
now associated with later maturity (although even ‘late’
menarche still occurs much earlier than in small-scale
societies, at approximately 14 years compared to around
17–18 years) (see also Cole, 2000).
Mcintyre & Kacerosky (2011) suggest that this shift
in life-history strategy from small-scale to industrial
societies fits with Day & Rowe’s (2002) developmental
overhead threshold model. This model is based on the
assumption that individuals cannot make the transition
from the growth phase to the reproductive phase
until they have reached a threshold body size (which
they term an ‘overhead threshold’, because a certain
fixed proportion of body tissue is required to support
reproductive functioning). As we have seen, human
females are required to reach a certain level of skeletal
maturity before becoming fertile in order to ensure a
pelvis of sufficient width to permit birth (Ellison, 1990).
One can therefore interpret this early investment in
skeletal growth as a form of overhead threshold. Day
& Rowe (2002) show that, in poor conditions, growth
prior to reaching the threshold is prolonged (because
growth rates are slow) and individuals switch to the
reproductive phase as soon as possible after the threshold
is reached, because they cannot afford to delay
reproduction any longer. By contrast, under very good
conditions, the time needed to reach the body size
threshold is shorter (due to faster growth rates), and
individuals continue to grow for longer after reaching
the threshold in order to increase later fecundity. Mcintyre
& Kacerosky (2011) therefore suggest that this kind
of effect gives rise to a negative relationship between
age at maturity and size under poor conditions (as seen
in small-scale human societies and early industrial society),
but a positive relationship under good conditions
(as seen in contemporary industrial societies).
Mcintyre & Kacerosky (2011) caution that their
interpretation is tentative, and note that the positive
relationship seen across industrialized nations could
be a statistical artifact, reflecting changes in both the
sources and degree of trait variation. They suggest, for
example, that under poor conditions, environmentally
caused variation in growth rates will largely determine
age at puberty (faster growth leading to earlier maturation)
but that, as conditions improve, environmentally
induced variation in growth rates and age at sexual
maturity will decline, and genetic differences between
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14 Gert Stulp and Louise Barrett
individuals will become more prominent. As Mcintyre
& Kacerosky (2011) note (echoing Bogin, Silva
& Rios, 2007), we still know surprisingly little about
population-level patterns and individual-level biological
processes in relation to age, growth rates and size at
maturity, all of which makes testing adaptive versus
non-adaptive hypotheses an ongoing challenge.
(4) Variation in growth: adaptive, constrained or
pathological?
Indeed, the question of what counts as the optimal
growth pattern, and whether to characterize the
effects of poor nutrition on height as an ‘adaptive’
norm of reaction or as ‘maladaptive’ is an ongoing
source of debate (see e.g. Bogin et al., 2007; Ellison
& Jasienska, 2007; Kuzawa, 2007). Whereas ‘adaptive’
in this particular context is taken to mean the
phenotypically plastic responses that produce the
optimal environment-specific body size, ‘maladaptive’
responses can be divided into those that reflect ‘constraints’
(defined as physiology directed at the same
goal as the unconstrained condition but unable to
achieve it fully) and ‘pathology’ (defined as physiology
that has been thrown off its normal optimal trajectory
and arrives at maladaptive outcomes) (Ellison &
Jasienska, 2007). This usage deviates from the definitions
more commonly used in evolutionary biology,
which are themselves often disputed (see e.g. Fox &
Westneat, 2010). Instead, it is linked more strongly to
evolutionary theorizing regarding ‘predictive adaptive
responses’ and developmental programming (Gluckman,
Hanson & Spencer, 2005; Langley-Evans, 2006).
Broadly speaking, these theories rest on the idea that
there is a mismatch between the conditions experienced
by the fetus and those experienced during the
post-natal period. This in turn is suggested to reflect
a broader mismatch between our evolved propensities
and the environmental conditions of the modern world,
particularly those of industrialized nations.
The costs experienced in later adult life, in terms
of extremely poor health outcomes, under conditions
when deprivation during infancy or childhood is severe,
are regarded as clear indicators of pathology in just this
sense (e.g. Barker et al., 1989; Barker & Clark, 1997).
Some of these costs seem to be related to ‘catch-up’
growth (the increase in growth velocity needed to put
individuals back on the optimal trajectory for their environment
once deprivation ends, e.g. Metcalfe & Monaghan,
2001; Monaghan, 2008), which suggests there
are trade-offs between excessive growth in early life and
later health outcomes (something which may explain
why secular trends continue over several generations,
rather showing a single rapid increase in a single generation
once good growth conditions are achieved: Cole,
2000). Even when deprivation is less severe, constraints
on achieving optimal growth can produce negative
downstream effects (e.g. being stunted is unlikely to lead
to optimal health in later life: Bogin et al., 2007), such
that the line between these two ‘maladaptive’ responses
is often unclear, and indeed may not be especially useful
when considering human growth patterns from a purely
evolutionary life-historical perspective. This is because
adaptations do not need to exert wholly positive effects
(and indeed, rarely do so) and we should expect to see
costs and benefits traded off against each other. Sickle
cell anaemia, as is well known, is a pathological consequence
of an adaptation that prevents malarial infection,
so the mere existence of costs (even when severe)
does not necessarily rule out an adaptive response.
Drawing a contrast between adaptive versus constrained/pathological
outcomes is also complicated by
the fact that cross-population comparisons of growth
trajectories and adult height are carried out by calibrating
against a reference group. If different populations
face different life-history trade-offs, and their heights
reflect the operation of an evolved reaction norm,
then such comparisons will never be straightforward,
given that these depend on the reference group used
to define the optimal (average, or ‘normal’) growth
trajectory. Stunting, for example, is identified by comparing
measurements of children’s heights to the USA
National Center for Health Statistics growth reference
population, but environmental conditions in, say, rural
Venezuela may actively favour shorter adult stature
with respect to life-history trade-offs, and hence result
in a locally attuned growth trajectory that is neither
‘constrained’ nor ‘pathological’ when viewed in an
evolutionary perspective. A more productive approach
perhaps would be to construct and compare individual
growth trajectories under a wide range of environmental
conditions, rather than assume that there
is an optimum growth trajectory that applies across
all environments. In other words, ‘adaptive’ can be
considered as an entirely relative term that compares
the success of individuals facing similar conditions:
extremely poor environmental conditions will obviously
constrain growth and reproductive patterns in some
way but, given those conditions, the patterns on display
may represent a ‘best of a bad job’ strategy and
cannot simply be dismissed as ‘maladaptive’. This bears
resemblance to Scrimshaw & Young’s (1989) notion
of ‘accommodation’, to describe those responses that
favour survival while simultaneously resulting in losses
to other important functions, and so impair optimal
adjustment to the environment.
A more radical suggestion is that we abandon the idea
that there is some ‘target’ height from which deviation
is possible (e.g. Tanner, 1963), thus leading to ‘constrained’
or ‘pathological’ outcomes. In this respect,
approaching the issue from a ‘developmental systems
theory’ (DST) perspective may prove valuable (Griffiths
& Gray, 1994, 2001). As Oyama, Griffiths & Gray (2001)
argue, the standard interactionist view, which sees traits
as a product of genes plus environmental influences,
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Evolution and human height 15
naturally leads us to think of context-sensitivity and
contingency as factors that lead the genetically derived
developmental ‘program’ to deviate from an evolved
‘norm’ in some or other way. It also points to the
possibility of neatly disentangling genetic from environmental
influences. DST instead views development
as inherently context-sensitive and contingent, with no
absolute priority given to any particular processes, and
no conception of a ‘target’ or ‘standard’ from which
it is possible to deviate. This would therefore mean
abandoning aspects of Tanner’s (1963) ‘target-seeking’
model of growth, which suggests that ‘children, no less
than rockets, have their trajectories, governed by the
control systems of their genetic constitution and powered
by energy absorbed from the natural environment’
(p. 818). Instead, individuals would be viewed as turning
out more or less the same because they are constructed
using the same suite of developmental resources, with
no underlying genetic program governing this process
nor defining what the organism is ‘meant to be’.
These suggestions for reconfiguring how we view
adaptation versus constraint/pathology are rendered
problematic, however, by the fact that, in anthropology,
the term ‘adaptation’ is used, not only in an evolutionary
sense, but also to refer to immediate adjustment
to the current environment (i.e. a person’s ability to
function unimpaired in everyday life), which brings in
aspects of well-being and life satisfaction. That is, when
we demonstrate that short stature under poor conditions
enhances fitness and is therefore evolutionarily
adaptive, nothing inherently good or bad is implied
by the term, even if this comes with certain costs. We
may very well consider such costs unacceptable from a
humanitarian perspective, however, because they indicate
a low level of adjustment to current conditions,
and hence a reduced quality of life (see e.g. Pelto &
Pelto, 1989). ‘Adaptation’ in this sense is thus a much
more loaded concept, and its usage has clear political
implications. For example, Seckler’s (1982) controversial
‘small but healthy’ hypothesis suggested that the
short stature resulting from mild to moderate malnutrition
was adaptive, because children who faced such
deprivation showed no impairment as adults other than
slowed growth and shorter adult height. In life-history
terms, we can see this argument as rather straightforward:
being small under conditions of marginal food
availability is beneficial because small bodies are easier
to maintain (even if this entails costs in other domains).
This hypothesis has come in for major criticism, however,
not only because the idea of a ‘no-cost’ adaptation
is disputed, and indeed there is considerable evidence
against it (e.g. Pelto & Pelto, 1989; Henneberg, Harrison
& Brush, 1998; Bogin et al., 2007), but also because
it holds implications for the provision of food aid and
other humanitarian efforts (i.e. if people are adapted
to low food intakes, it implies there is no need to supplement
their diet, even if they fall short of Western
standards of nutrition). In other words, deciding on
what counts as ‘adaptive’ or ‘impaired’ (pathological)
will never be a simple matter because these terms can
never be divorced from their cultural and political context.
This issue obviously requires a more thorough and
careful discussion than we can provide here, but we feel
it is important to mention this, not least because it highlights
that height cannot be viewed simply as a straightforward
‘biological’ trait (see also Butt, 1999; Spencer &
Logan, 2002).
(5) Mortality, growth and height
In addition to nutritional influences on development
and life-history processes, any factors that acutely
increase the risk of mortality for particular age-classes
can also have an effect on growth rates. As juvenile mortality
increases, and the chance of reaching adulthood
decreases, postponement in the onset of reproduction
becomes more costly and growth rates should thus
increase, giving rise to an earlier onset of sexual maturity
(see e.g. Moorad & Promislow, 2010; Walker et al.,
2006). In their detailed study of small-scale subsistence
societies, Walker et al. (2006) report evidence for just
such a trade-off among three pygmy populations, the
central African Baka, the Hiwi of Venezuela and the
Negritos of the Phillipines, who all show an accelerated
developmental pattern. These groups show both
faster and more linear growth across development than
expected for their body size, and do so despite poor
environmental conditions. In addition, the adolescent
growth spurt is either diminished or absent (although as
only cross-sectional data were used to determine these
effects, this latter point should be viewed with some
caution). Walker et al. (2006) also show that, for the
Hiwi, Negritos and Baka, juvenile mortality is positively
associated with accelerated growth rates relative to age.
Baka pygmy girls show a childhood growth rate of
7.1 cm/year, while Hiwi girls grow at an almost identical
rate of 7 cm/year (Walker et al., 2006). These
values approach or exceed those of USA children
(average childhood growth rates of 6.5 cm/year). As a
consequence, girls in these groups display much higher
levels of skeletal maturity at much younger ages relative
to other groups. While a Baka or Hiwi girl has reached
about 70% of her adult size by age 10, in other groups,
such as the Maya, girls have reached only 40–45% of
their adult size by this age (Walker et al., 2006). As we
have seen, menarche is cued to skeletal maturity, and
occurs only after girls have completed ∼95% of their
growth (Ellison, 1990; Kramer & Greaves, 2010). This
suggests that fast growth is geared toward permitting earlier
reproduction and occurs at the expense of larger
body size (because growth ceases at a younger age, and
accelerated growth rates cannot fully compensate for
this reduction in the pre-pubertal growth period).
Migliano, Vinicius & Lahr (2007) also found support
for this idea in their detailed analysis of pygmy versus
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16 Gert Stulp and Louise Barrett
non-pygmy populations [but see Becker et al. (2010)
for criticism of this study, and Migliano, Vinicius &
Lahr (2010) for a response]. Assuming that life-history
trade-offs do, in fact, explain short stature and accelerated
growth among these pygmy populations, it raises
the question of why other groups that experience high
juvenile mortality do not exhibit this same pattern.
Walker et al. (2006) suggest this may reflect habitat differences:
in the humid forest habitats occupied by pygmies,
mortality risks from disease are particularly acute,
and larger juvenile body size may confer a direct benefit
via a more robust immune system, as well as allowing for
earlier onset of reproduction. In the drier, higher elevation
habitats occupied by many of the other groups in
their sample, disease risk lessens and malnutrition and
starvation become more important sources of mortality,
which favours slower childhood growth.
The developmental patterns shown by pygmy populations
are underpinned by distinctive hormonal profiles
that have a genetic basis (Dávila et al., 2002), and stature
in these populations accordingly shows relatively low levels
of plasticity compared to other groups (Walker et al.,
2006; Becker et al., 2011). The Baka, Hiwi and Negritos
growth response may therefore reflect selection for
a specific life-history pattern, with growth rates more
strongly fixed by natural selection, rather than reflecting
the expression of a flexible norm of reaction. In this
respect, data from Pumé girls and women in Venezuela
are especially valuable: early reproduction is common
within this high-mortality population, with a mean age
at first birth of 15.5 years. This does not occur in the context
of either very short stature or distinctive hormonal
profiles compared to other northern South American
indigenous groups, however, suggesting that this
specific growth pattern has not come under selection
(Kramer & Greaves, 2010). Thus, any increase in growth
rates seen among these girls can more confidently be
attributed to the expression of a reaction norm.
Similar to the Baka and Hiwi, Pumé girls have reached
87% of their adult height by age 10. As might be
expected, the timing of their peak growth velocity
occurs considerably earlier compared to other groups,
and persists for longer, and hence they do not show a distinct
adolescent growth spurt (Kramer & Greaves, 2010)
(this, incidentally, suggests that, contrary to current consensus,
an adolescent growth spurt, while unique to
humans, is not a unique feature of all human groups:
Walker et al., 2006). Pumé girls illustrate clearly that
faster growth rates can occur as a plastic developmental
response under poor environmental conditions and
high mortality risk, giving rise to early and advantageous
reproduction, and can be achieved in the absence of
stunting.
It is clear that life-history trade-offs account for many
of the differences in height seen within and between
populations, and that the timing of menarche in contemporary
societies is constrained by the rates at which
women, in particular, achieve the level of skeletal
maturity needed to support reproduction. From an
evolutionary perspective, this suggests that height itself
is less important as a trait than the underlying components
of growth rates and the timing of reproductive
maturity that give rise to it. This raises the question of
whether height does, in fact, carry any selective advantage
independent of its links to life history. Aspects of
the obstetric dilemma suggest this might be the case,
at least for women, and stature has also been linked to
various ecological selection pressures, suggesting this
is a question worth pursuing. In Section VI, then, we
assess the evidence that natural selection acts on height
in contemporary human populations.
VI. NATURAL SELECTION ON HEIGHT
(1) Mortality risks and height
(a) Height, health and mortality in adults
It seems reasonable to suppose that natural selection
will act on height to the extent that this trait is related
to health and survival (Batty et al., 2009). Generally,
height is positively related to measures of health (Silventoinen,
Lahelma & Rahkonen, 1999; Stulp et al., 2014),
although curvilinear effects for women have also been
observed (Silventoinen et al., 1999). Moreover, the relationship
between height and health is much stronger
(and positive) when assessing short to average height
men than when comparing average height to tall men
(Stulp et al., 2014). It seems likely that there are diminishing
returns to increasing height, and very tall men
may have much poorer health outcomes.
As one might expect given these patterns in relation to
health, there is also a relationship between height and
all-cause mortality. A review by Sear (2010) indicated
that, in Western populations, taller men have lower
mortality than shorter men. Taller women also experienced
lower mortality than shorter women in most
studies, although some reported a curvilinear effect,
with average-height women experiencing the highest
survival (Sear, 2010; but see Samaras, 2009). A recent
meta-analysis, with data on over 1 million individuals
generally supports Sear’s (2010) analysis: taller men
and women had a lower risk for all-cause mortality,
although there were opposing effects of height on mortality
for specific causes of deaths. In general, shorter
people were more at risk of dying from cardiovascular
and non-cancerous disease, whereas taller people
were more at risk of death from cancer (Wormser
et al., 2012). The overall increased risk of mortality for
shorter people may be due partly to associated differences
in socioeconomic background. Although some
indicators of economic background were controlled for
in this meta-analysis, it is also the case that, as we have
seen, poor nutrition during childhood may lead to both
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Evolution and human height 17
reduced height and poorer health as adults; controlling
for current measures of economic status does not necessarily
eliminate or control for these childhood effects.
With respect to increased cancer risk of taller individuals,
one suggestion is that they simply have a greater
number of cells in their body, and hence an increased
risk of defects in cellular repair mechanisms. This fits
with the idea that larger bodies may be more costly to
maintain and repair over time. The weight of evidence
thus suggests that short men and women are at a general
disadvantage with respect to overall health and survival
in Western populations, while taller people may experience
health risks of a more specific nature. Too few
studies have addressed these same issues in non-Western
populations to draw any meaningful conclusions on this
front (Sear, 2010).
(b) Height and infant mortality
In addition to their greater mortality risks, shorter
women are also at a disadvantage with respect to successfully
raising children to adulthood: both child morbidity
and mortality are negatively related to maternal height
(Subramanian & Ackerson, 2009). Shorter women have
been shown to be at a higher risk for complications during
pregnancy and delivery, such as stillbirth (Bresler,
1962), failure to progress in labour (Sheiner et al.,
2005), and the need for Caesarean sections (Kirchengast
& Hartmann, 2007). Stulp et al. (2011) found
that shorter British women (i.e. 1 S.D. below mean
height) were one and a half times more likely to need
an emergency Caesarean section than taller women
(1 S.D. above mean height) when giving birth to their
first child. Furthermore, over half of British women
under 150 cm needed a Caesarean section. In addition
to maternal height, the difference in height between
parents was also linked to a greater risk of birth complications
in this study: the likelihood of an emergency
Caesarean section was significantly higher in cases
where the father was very much taller than the mother
(particularly when the baby is heavy) (Stulp et al., 2011).
Thus, one could argue that the birth complications suffered
by shorter women, often due to obstructions of
the birth canal, represent a significant selection pressure
on height, given that pelvic dimensions increase
with stature. A recent study by Kurki (2007), however,
argues that, in short-statured populations, pelvic geometry
(size and shape) has shifted to protect the obstetric
canal; that is, selection has acted on pelvis shape to
reduce the risk of birth complications, rather than
selecting against short stature. It is also the case that,
when birth complications do arise, this is often due to
deformation of the pelvis due to malnutrition, rather
than because of short stature per se (Wells et al., 2012).
The adverse effects of short stature during pregnancy
and parturition also appear to carry through
to newborn health. Shorter women are more likely to
give birth to infants with relatively low birth weights
(Camilleri, 1981) and relatively low Apgar scores (a
health assessment administered directly after delivery:
Camilleri, 1981; Casey, McIntire & Leveno, 2001), both
of which are predictors of child morbidity and mortality
(McIntire et al., 1999; Casey et al., 2001). Maternal
height is also negatively related to child mortality both
in developing (Monden & Smits, 2009) and low-to
middle-income countries (Özaltin, Hill & Subramanian,
2010); indeed, the literature shows very clearly
that taller women have increased child survivorship
in non-Western populations. Even in a contemporary,
industrialized population with very low levels of child
mortality, shorter mothers had higher child mortality
than taller mothers (Stulp et al., 2012d). Although these
patterns between maternal height and child morbidity
and mortality appear to be quite general, it is unclear
whether they hold for all populations.
Overall, then, the evidence on mortality risks suggests
that it is possible for natural selection to be acting
currently on human height, and that it may do so
differentially between the sexes. Effect sizes in the available
studies are generally small, however, and it seems
unlikely that selection could exert any influence without
also influencing differential fertility in additional ways.
One obvious candidate is via mate choice and sexual
selection. Indeed, many of the health effects observed
may influence mate choice processes, and it seems likely
that these might exert a greater influence on fitness differentials
in contemporary low-mortality populations.
(2) Sexual selection and height
Sexual selection could operate on height either by
increasing competitiveness within the sexes or by
increasing the probability of being selected as a mate
by the opposite sex. In considering the empirical evidence
for sexual selection on height in humans, some
caution is warranted: most studies do not present direct
evidence that greater competitiveness and/or attractiveness
translates into higher reproductive success
among contemporary populations. Rather, they deal
only with preferences for particular traits, and place the
emphasis on this as evidence of past selection, rather
than attempting an assessment of the opportunity for
selection in the present day.
(a) Intrasexual competition
Height has been associated with physical dominance
in human males, mirroring findings from other mammals
(Ellis, 1994): taller men are physically stronger
(Sell et al., 2009; Puts, 2010), more aggressive (Archer
& Thanzami, 2009), and are argued to have better fighting
ability (von Rueden, Gurven & Kaplan, 2008; Archer
& Thanzami, 2009; Sell et al., 2009). The physical superiority
of taller men is thought to contribute significantly
to their achieving greater access to resources and status
within social groups. In modern Western societies, it
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18 Gert Stulp and Louise Barrett
seems unlikely that physical strength and fighting ability
have any direct influence on social status and resource
acquisition in terms of male–male physical combat.
There are, however, clear social gradients in height that
reflect differential access to resources: in a study examining
10 different European countries, Cavelaars et al.
(2000) found that, without exception, more highly educated
individuals were taller than those who were less
educated, with height differences ranging from 1.2 to
3 cm. Similarly, a meta-analysis by Judge & Cable (2004)
found that height was consistently positively related to
leadership, income and professional achievement, all
of which are proxies for access to resources. The positive
relationship between height and several measures of
social status has been well established (e.g. Case & Paxson,
2006; Magnusson, Rasmussen & Gyllensten, 2006;
Batty et al., 2009; Deaton & Arora, 2009), although relationships
need not always be linear, and, as is the case for
health, diminishing returns on income with increasing
height have also been observed (e.g. Stulp et al., 2014).
Several hypotheses have been put forward to explain
this relationship between stature and status including
the correlated influence of parental resources on height
and social success (Persico, Postlewaite & Silverman,
2004), the decreased health of shorter men and women
(Silventoinen et al., 1999) and the increased cognitive
ability associated with height (explained by factors such
as genes and/or nutrition (Case & Paxson, 2006; Silventoinen
et al., 2006). Intriguingly, Persico et al. (2004)
observed that, even after controlling for all the above
factors, taller individuals retained their social advantage,
raising the possibility that height has a direct
influence on the ability to achieve high social status
in modern Western society (see also Cinnirella, Piopiunik
& Winter, 2011). Indeed, the upward social mobility
of taller compared to shorter individuals (Peck, 1992;
Cernerud, 1995; Krzy ̇zanowska & Mascie-Taylor, 2011),
even when familial circumstances are controlled (e.g.
by examining sibling pairs: Bielicki & Charzewski, 1983;
Magnusson et al., 2006) suggests there is more to height
than simply parental influences.
One way in which taller individuals may achieve
higher social status is by increasing the probability of
winning non-physical confrontations. There is currently
only circumstantial evidence for this idea, including
the higher proportion of popular votes that taller USA
presidential candidates receive (Stulp et al., 2013d),
the increased number of unfair offers made by taller
individuals in economic games within a virtual reality
setting (Yee & Bailenson, 2007), the increased authority
of taller football referees on the pitch (Stulp et al.,
2012a), and the greater influence of perceived taller
individuals in a negotiation task (Huang, Olson &
Olson, 2002). It seems possible that this occurs because
taller men are perceived as more competent and
authoritative (Young & French, 1996; Judge & Cable,
2004; Cinnirella & Winter, 2009; Marsh et al., 2009).
Whatever the mechanism, there is a clear relationship
between height, resource acquisition and social status.
This potentially could contribute directly to mating success
via male competitiveness, although it seems likely
to do so only under conditions where female choice
is tightly constrained. In most modern settings, male
height as an indicator of resource-holding potential is
more likely to exert its effects via intersexual selection,
i.e. as a component of female choice.
(b) Height and intersexual preferences
One of the central premises of intersexual selection is
that traits that signal high reproductive potential should
be preferred by the opposite sex (see e.g. Kuijper, Pen
& Weissing, 2012). If height acts as an accurate cue to
resource-holding potential by men, and if this increases
the direct reproductive benefits that accrue to women,
then a preference for greater height by women is potentially
adaptive. In addition, as taller men are healthier
and show lower mortality than shorter men then, to
the extent that these traits are heritable, females will
gain indirect benefits as well. There may, however, be a
limit to women’s height preferences, given the finding
that women partnered to men much taller than themselves
experience an increased risk of birth complications
(Stulp et al., 2011). Thus, women potentially face a
trade-off between the benefits associated with increased
partner height and the cost of increased mortality risk (it
should be noted that we are speaking here from a functional
evolutionary perspective, and not from a proximate,
conscious decision-making perspective, although
the latter will factor into this). Moreover, there may be
diminishing returns on height, which could mean that
men of above-average height do not provide substantively
more benefits than average-height men (see e.g.
Krams et al., 2014; Stulp et al., 2014).
From the male point of view, we have already noted
that short women are at a disadvantage when it comes
to health, mortality, obstetric problems, and offspring
survival. A preference for average height or taller
women could, therefore, be considered adaptive, but
again there may be trade-offs involved: there is some
evidence to suggest that shorter women are genetically
predisposed to display an earlier age at first birth, which
potentially compensates for their (children’s) higher
mortality risks (Stearns et al., 2012; Stulp et al., 2012d).
Given the complexity of the potential selection pressures
operating on humans, and the limits on males
as well as females to invest in young, predicting the
height preferences of each sex with respect to adaptive
outcomes is therefore complex, and not always obvious.
In addition, as we have noted, most studies in this area
have focused largely on mate preferences, and take no
account of the subsequent processes of mate choice and
pair formation. As the latter can lead to significant deviations
from the stated preference of each sex, the lack
of information on these processes is problematic. With
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
Evolution and human height 19
these additional caveats in mind, we now review the
available evidence relating to intersexual preferences
for height.
Height is a partner characteristic known to be valued
by both men and women – although women value
height more highly (Pierce, 1996) – and preferences
for partner height have been well studied (reviewed
by Courtiol et al., 2010b). In general, average-height
women and above-average-height to taller men are
considered most attractive by the opposite sex in
laboratory-based preference studies. In both men and
women, questionnaire data also suggest that, as the
height of a given individual increases, so does the preferred
height of their partner, indicating preferences
for assortative mating (Courtiol et al., 2010b; Stulp,
Buunk & Pollet, 2013b: see also Kurzban & Weeden,
2007; Stulp et al., 2013c). Men’s preferences in this
regard are entirely relative: they prefer their partners
to be shorter, but show no preference for shortness per
se (Courtiol et al., 2010b). By contrast, women seem to
value male height in a more ‘absolute’ sense; accordingly,
a male-taller preference is more pronounced in
women (Stulp et al., 2013b,c). Men should not be too tall
compared to their female partners, however: excessive
height differences are considered unacceptable, and
several studies have reported a maximum acceptable
height difference of around 25–26 cm (Pawlowski,
2003; Fink et al., 2007; Salska et al., 2008).
A conflict over height preferences between the
sexes has also been observed, with women preferring
larger partner height differences than men (Courtiol
et al., 2010b; Stulp et al., 2013a,b). This can lead
to ‘sub-optimal’ pair formation, where both sexes
are forced to compromise on their preferred height
difference (Stulp et al., 2013a). Preferred height differences
are also dependent on an individual’s own
height: studies using French, Polish, Dutch and USA
samples have shown that both shorter men and taller
women prefer smaller partner height differences than
do taller men and shorter women (Pawlowski, 2003;
Courtiol et al., 2010b; Stulp et al., 2013a,b). It should
be noted that while studies on height preferences
from industrialized populations are fairly consistent,
studies examining non-industrialized populations can
be strikingly different (e.g. Sorokowski et al., 2011;
Sorokowski & Butovskaya, 2012) Currently, we cannot
explain such differences, but they may be contingent
on ecological differences between populations, and the
‘optimal’ height within such populations. Alternatively,
methodological differences may be responsible.
The real question here, of course, is whether people’s
preferences translate into mate selection. There is some
suggestion that it does. Male height has been shown
to be positively related to the likelihood of having a
date (Cawley, Joyner & Sobal, 2006), dating frequency
(Shepperd & Strathman, 1989), having a partner and
multiple long-term relationships (Nettle, 2002a), being
married (Harper, 2000; Pawlowski, Dunbar & Lipowicz,
2000; Herpin, 2005), having multiple wives (Mueller &
Mazur, 2001) and having a partner who scores more
highly on relevant mate-choice characteristics (Oreffice
& Quintana-Domeque, 2010; Stulp et al., 2014). Curvilinear
effects of height on the age at marriage and
probability of marriage are also observed (Stulp et al.,
2012c; Manfredini et al., 2013). For women, shorter
individuals have been shown to be less likely to date
(Cawley et al., 2006), but also to be more preferred as
dates or more frequently dated (Shepperd & Strathman,
1989). Furthermore, taller women have been reported
to have lower probabilities of marriage (Harper, 2000;
Stulp et al., 2012d) and a later age at marriage (Stulp
et al., 2012d). Also average-height women have been
observed to have the highest number of relationships
(Nettle, 2002b). As observed for the mate preferences
with respect to stature, results are not consistent across
the globe: whereas in African pygmies and rural Gambian
men, height is positively related to number of
marriages (Sear, 2006; Becker et al., 2012), among the
Hadza height was not related to probability of marriage
(Sear & Marlowe, 2009).
If we look at patterns of height within couples, we also
find that many of the above preference rules are realized
in actual couples, suggesting that laboratory-based
preferences play out in the real world. For instance,
assortative mating is widely observed in industrialized
populations (Gillis & Avis, 1980; Spuhler, 1982;
McManus & Mascie-Taylor, 1984; Silventoinen et al.,
2003a; Oreffice & Quintana-Domeque, 2010; Courtiol
et al., 2010a; Stulp et al., 2013c). Furthermore, both the
male-taller and male-not-too-tall norms are found in
actual couples (Gillis & Avis, 1980; Sear, 2006; Becker
et al., 2012; Stulp et al., 2013c). In addition, partner
height differences have been shown to be dependent
on an individual’s own height in a sample of actual
British couples (Stulp et al., 2013c).
There are two relevant points to add. First, realized
associations with respect to height between partners
are much weaker than the associations found in preference
studies (Courtiol et al., 2010a,b; Stulp et al.,
2013c), particularly for women (Courtiol et al., 2010a)
implying that such preferences are only moderately
realized in actual couples. In addition, non-random
pairing with respect to height is not always apparent
in non-industrialized populations. Although there is
support for assortative mating and the male-taller norm
in some non-Western populations (Mexico: Malina
et al., 1983; Bolivia: Godoy et al., 2008; Pakistan: Ahmad,
Gilbert & Naqui, 1985; Cameroon: Pieper, 1981; Becker
et al., 2012), there are also a number of studies that show
no evidence of these effects (Korea: Hur, 2003; Gambia:
Sear, Allal & Mace, 2004; Hadza: Sear & Marlowe, 2009).
As already noted, it seems likely (and indeed obvious)
that individuals take into account a variety of other
characteristics besides height when choosing a mate.
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20 Gert Stulp and Louise Barrett
Having said this, although the effects are modest,
height does play a role in the partnering process in at
least some populations. Combined with the evidence
relating to resource acquisition, health and mortality
risks, it is therefore worth asking whether height significantly
influences reproductive success in contemporary
humans.
(3) Does height influence reproductive success?
Before we address whether height is associated with
reproductive success, we should briefly mention a few
further caveats relating to methodological issues. There
are, for example, problems of non-representative samples
(e.g. the inclusion of only healthy individuals and
those that have not yet completed their reproductive
lifespan, the exclusion of childless individuals, delinquents,
twins) that may affect results, although the exact
manner in which they may do so is often unclear. There
is also a lack of control of potentially confounding variables
in some studies (e.g. education and income), and
many have small sample sizes. As selection gradients are
typically low (Kingsolver et al., 2001), substantial samples
are required to detect any effect; some studies,
therefore, may simply be underpowered. Thus, a certain
degree of caution is needed when interpreting many of
the available studies. For a more thorough discussion of
these issues, see Stulp et al. (2012b,c,d).
(a) Female height and reproductive output
The relationship between female height and reproductive
output was assessed in 29 populations [Table 1;
this is an extension of that in Stulp et al. (2012d), see
their study for further details]. Even brief inspection
of Table 1 reveals that the results are highly variable,
with null, positive, negative and curvilinear effects all
reported. This may arise at least partly from methodological
factors, most notably variability in age ranges
and whether only parous women were included in the
sample. These caveats aside, it is clear that most variability
is found among non-Western nations, whereas
among Western populations, there is a more consistent
negative association between female height and reproductive
success (in those cases where a significant relationship
is found) (Stulp et al., 2012d).
High levels of variability in the relationship between
height and reproductive success across populations are
perhaps also to be expected (if they are not simply the
result of methodological differences) because selection
pressures are also likely to differ substantially across
space and time (Siepielski, DiBattista & Carlson, 2009).
Moreover, from a life-history perspective, a single height
optimum across all environments is inherently unlikely:
the trade-offs between growth, survival and reproduction
should give rise to variable body size optima that are
dependent on environment-specific levels of resource
abundance and mortality regimes (Sear, 2010). That is,
the height that maximizes reproductive success within
a population should be expected to differ from other
populations, given local mortality regimes and ecological
conditions. It is, however, interesting to consider how
the heights that maximize reproductive success vary in
absolute terms as this helps us appreciate that what constitutes
tall or short height in one population may not
do so in another. In addition, it allows us to gain some
insight into whether female reproductive success is maximized
within a particular range of heights across all
populations, regardless of the nature of the relationship
within a particular population.
Inspection of Table 1 reveals that there is perhaps less
variability in the absolute heights that maximize reproductive
success than one might imagine, given the variability
in the direction of the association across populations.
‘Average-height’ to ‘short’ women in a Western
context, for example, would not be considered short relative
to their counterparts in other regions, and would
even be considered as relatively tall in some of them.
Equally, among those non-Western populations where
women of average height show the highest reproductive
success, such women would be considered relatively
short in a Western context; indeed the height
of such women approximates the height of the shortest,
most reproductively successful women in the USA
(Stulp et al., 2012d). Similarly, ‘tall’ women who do better
reproductively in a non-Western context fall within
the range of average to short height in a Western context.
Although speculative, one can hypothesize that the
trade-off between growth and reproduction may therefore
reflect some upper physiological limit that applies
across all populations, regardless of ecological conditions,
in much same way that the mechanical limit of
pelvis size is hypothesized to constrain the minimum
height that women must achieve. Although good conditions
may permit growth to continue beyond the minimum
threshold needed to support reproductive functioning
and so increase productivity, it may be possible
to extend such growth only so far before it begins to
have a negative effect on reproductive output because
of the delay in sexual maturity. This is most likely to
be due to a reduction in the overall length of the
reproductive lifespan, which is far less flexible at the
tail-end with respect to the onset of menopause, than
at the beginning with the onset of menarche (Morabia
& Costanza, 1998; Burger, DeLong & Hamilton,
2011). Growing very much taller than the minimum
height required for successful reproductive functioning
(i.e. tentatively, beyond the heights of 1.60–1.70 m seen
here) may therefore require exceptional environmental
conditions that allow for more rapid growth both
prior to and after the threshold is reached (i.e. a faster
growth velocity prior to menarche, and a slower decline
in growth once this has been reached). It is possible
that conditions in some Northern European countries,
particularly the Netherlands, where the secular trend
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
Evolution and human height 21
Table 1. A summary of studies on the relationship between height and reproductive success
Female height Male height
Study Population N Effect Average Optimum N Effect Average Optimum
Lasker & Thomas (1976) Mexicans who have lived in
USA
147 – ∼151 ∼215 – ∼162
Shami & Tahir (1979) Pakistana 827 Curv ∼152–153 154–155 860 Curv ∼164–165 166–167
Mueller (1979) Columbiaa 349 – ? 338 Curv ? ?
Mueller, Lasker & Evans
(1981)
Mexicans in Mexico and USA 121 – ? 159 – ?
Martorell et al. (1981) Indians in Guatamalaa 380 Pos 142 153
Brush, Boyce & Harrison
(1983)
Papua New Guinea 152 Curv 151 151
Goldstein & Kobyliansky
(1984)
Mexicans in Mexico and USA 230 –b ? 230 – ?
Devi et al. (1985) India 291 Neg 161 140
Baqui et al. (1994)b Bangladesh 2417 – 149
Winkler & Kirchengast (1994) !Kung san from Namibia 114 – 161
Kirchengast & Winkler (1995) Urban !Kung san 59 Neg 171 159
Kirchengast & Winkler (1995) Rural !Kung san 78 Pos 171 182
Kirchengast & Winkler (1996) !Kung san from Namibia 93 Neg 149 139
Kirchengast & Winkler (1996) Kavango from Namibia 85 Neg 160 150
Kirchengast (2000) !Kung san from Namibia 65 Neg 149 149 103 – 160
Sear et al. (2004) and Sear
(2006)
Rural Gambia 216 Pos 158 ∼167 303 – 168
Pollet & Nettle (2008) Rural Guatamala 1989 Curvc 147 148
Fielding et al. (2008) China 6709 Neg 154 144 2620 Neg 165 153
Sorokowski, Sorokowska &
Danel (2013)b
Yali West Papua 54 – 151 52 – 141
Becker et al. (2012) Baka pygmies and
Nonpygmy Nzimé
∼99 – 146 ∼99 – 156
158 168
Courtiol et al. (2013)b, d Rural Gambia 2818 Var ∼158
Clark & Spuhler (1959) USA 324 – ? 136 Curv ∼172 ∼172e
Damon & Thomas (1967) USA 2616 Curv ∼173 178
Bailey & Garn (1979) USA ∼1261 Neg 158 ∼146
Scott & Bajema (1982) USA 600 – 162 621 Curv 177 ∼176
Pawlowski et al. (2000)) Poland 3201 Pos 172 ∼185
Mueller & Mazur (2001) USA 322 Pos ∼178f ∼190f
Nettle (2002a,b) UK 3554 Neg 162 151 4586 No 177
Deady & Law Smith (2006) Caucasians; UK, USA, Canada,
Australia
315 Neg 164 150
Helle (2008) Finland 271 No 164
Genovese (2008) USA 192 – ?
Nenko & Jasienska (2009) Rural Polanda 328 – 159
Byars et al. (2010) and Stearns
et al. (2012)b
USA 2227 Neg 161 148 2655 Curv 174 ∼174
Stulp et al. (2012c,d) USA 4069 Neg 164 152 3578 Curv 179 177
Stulp et al. (2012b)b,g USA 1853 Neg 164 152 1669 Curv 179 177
Silventoinen et al. (2013)a Swedish twins 4236 – 164 3600 Curvh 177 ∼177
See Stulp et al. (2012a,b) and original studies for more elaborate description of samples and how the effect of height was established. Studies
above the middle line are considered non-industrialized and non-Western.
Effect refers to the effect of height on reproductive success (Pos: positive; Neg: negative; Curv, curvilinear; –, no effect observed; Var, variable
selection pressures over time observed).
Optimum refers to those heights that were associated with highest reproductive success, either by determining optimum of curve, or identifying
height bin associated with highest fertility. When a positive/negative association of height was observed, heights of 2 S.D. above or below the
means are reported as the optimum.
aOnly individuals with at least one child were included.
bNot included in reviews of Stulp et al. (2012a,b).
cIn Stulp et al. (2012a) it was wrongly concluded that the effect was positive and that the optimum was at tall heights (this held true for child
survival, not for the number of children ever born). On the basis of the regression equation provided in Pollet & Nettle (2008), it is clear that
average-height women have higher fertility with an optimum at 151 cm.
dThis study used similar data to those used in Sear et al. (2004), although the analyses were very different (see text for discussion).
eEstimate based on graph as provided by Mitton (1975) who reanalysed the data of Clark & Spuhler (1959).
f Actual heights were not available, but height was measured in percentiles. Height admissions for the military were between 157 and 198 cm, and
we determined heights on the basis of these values.
gThis study is not independent of Stulp et al. (2012a,b) since it uses data on brothers and sisters.
hPoisson regressions revealed no effects, but men (male twins) in the third quintile were more likely to have a child, and to have one or two
children. The effect of height was very weak and almost non-existent in the graph.
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
22 Gert Stulp and Louise Barrett
in height apparently is on-going (Fredriks et al., 2000;
but see Schönbeck et al. 2012), approximate such conditions.
Here, women may be able to grow far beyond the
minimal pelvic threshold to a height that significantly
reduces the risk of obstetric problems via increased
pelvic width, while simultaneously allowing them to benefit
from the increased fecundity associated with larger
body size.
Outside of such exceptional conditions, where
reproductive-success-maximizing heights are short
relative to the population average, an earlier start to
reproduction appears to compensate for increased mortality
risk among short women. In line with this, in some
high-income populations, shorter women tend to reach
menarche earlier and reproduce at a younger age than
women of taller stature, suggesting they are ‘ready for
reproduction’ at an earlier age than their taller counterparts.
As age at first birth is a crucial factor in determining
overall reproductive success among women, especially
in low-fertility industrial nations (for a list of studies,
see Stearns et al., 2010), selection may thus favour
women who terminate growth earlier, and so achieve a
younger age at first birth. Further weight is added to this
argument by the observation that a genetic correlation
exists between female height and age at first birth. That
is, women who bear their first child at an early age also
show a genetic predisposition to be shorter than average
(Stearns et al., 2012). Thus, as Stearns et al. (2012) point
out, both the phenotypic (i.e. the life-history trade-off)
and genetic correlation between height and age at
first birth may explain why shorter women often attain
higher reproductive success. This seems to be particularly
true in contemporary industrial societies, where
this head-start more clearly outweighs the higher mortality
risks they experience; possibly due to advanced
medical care which helps to minimize these risks.
There is also good evidence to suggest that, for
women who are tall relative to their population average,
increased survivorship could potentially compensate for
a delayed start to reproduction in environments where
mortality is high. A positive association between female
height and child survival probabilities is well established
for both developing countries (42 countries: Monden &
Smits, 2009) and low- to middle-income countries (54
countries: Özaltin et al., 2010; but see Devi, Kumari &
Srikumari, 1985). In poor-quality environments, height
is likely to be a reflection of health and nutritional status
(Silventoinen, 2003; Sear et al., 2004), and hence
a greater ability to access resources, both of which are
likely to have a positive influence on childhood survival
and reproductive success (Martorell et al., 1981). In line
with this, Sear et al. (2004) found that taller women in
the Gambia achieved higher reproductive success than
short women, despite a later age at first birth. In this
case, taller women not only experienced higher rates
of child survival, but were also able to compensate for
their delayed start by giving birth to more children
overall. It is interesting to note, however, that Courtiol
et al. (2013) show a different relationship between
height and fertility over the same period, using the
same data set. In their analyses, which tracked changes
in selection across the demographic transition, they
found that, over the same period studied by Sear
et al. (2004) (∼1950–1975), selection favoured shorter
women with a higher BMI. From 1975 onwards, this relationship
shifted, with selection favouring taller women
with a lower BMI (possibly linked to the establishment
of a medical facility in 1975). Comparison of
these two studies is complicated by the fact that different
data-selection procedures were used, which may
account for the contrasting patterns seen. In essence,
Sear et al. (2004) show that taller women born in 1925 or
earlier, who survived to the age of 50, had most children,
whereas Courtiol et al. (2013) show that, for all women
born before 1975, when assessed on a yearly basis, selection
appears to favour shorter women.
Although height is highly heritable, and a genetic
response is likely, these kinds of phenotypic correlations
with fitness do not necessarily reflect a genetic correlation
with fitness (Morrissey, Kruuk & Wilson, 2010).
To establish whether selection on height will generate a
genetic response in the next generation, data on families
or actual genomic data is needed. Byars et al. (2010)
represents one of the only examples of such a study:
using a sample of USA women from the longest running
multi-generational study in medical history, they
showed that natural selection is operating in women to
drive height downwards.
Another factor to consider when discussing how
height might influence reproductive success is the ability
to attract a mate and form a reproductive partnership.
Stulp et al. (2012d), for example, found that
taller women in a USA population were more likely to
remain unmarried and, among those that did marry,
they tended to marry late. Age at marriage cannot, of
course, be considered an accurate proxy of mate attractiveness
or value. Rather, it may equally well signify the
selectivity of the woman herself. Taller women, at least
in some populations, may be more selective, and less
likely to ‘settle’, than shorter women. Indeed, given that
shorter women appear to have a genetic predisposition
to bear children at an earlier age, it seems plausible that
this same biological inclination affects other aspects of
their physiology and psychology as well (Deady & Law
Smith, 2006): shorter women perhaps possess higher
fertility motivations, which manifest at an earlier age.
Shorter women in industrial societies may therefore
show greater motivation to find a committed partner
and begin a family while still very young.
(b) Male height and reproductive output
For men, data were available for 24 different populations
(Table 1). Again, as for females, a variety of effects
were reported, and again, there was more consistency
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
Evolution and human height 23
in Western than in non-Western populations (for full
discussion, see Stulp et al., 2012c). For USA populations,
in particular, average-height men tend to show the
highest reproductive success. Given the above associations
between male height and enhanced access to
resources and mates, a positive relationship between
male height and reproductive success within certain
populations is not hard to explain. Equally, given our
consideration of life-history trade-offs and the potential
benefits of short stature in offsetting mortality risks
against future reproduction, a relationship between
short stature and greater reproductive output can also
be accounted for under conditions where overall mortality
risks are high for particular age-classes. In addition,
temperature, nutritional stress, manoeuvrability
through forests, and high adult mortality have all been
suggested as examples of ecological factors that may
favour shorter heights (e.g. Cavalli-Sforza, 1986; Bailey
et al., 1989; Diamond, 1991; Perry & Dominy, 2009).
Explaining why men of average height should experience
higher reproductive success in contemporary societies
is rather more of a puzzle.
Some clues are offered by the detailed analysis of Stulp
et al. (2012c) on the Wisconsin Longitudinal Sample.
Although height was not related either to being married
or to the total number of marriages, average-height
men married at an earlier age than shorter and taller
men. Controlling for age at marriage attenuated the
relationship between height and reproductive success,
whereas controlling for education and income did
not, suggesting that the relationship was at least partly
mediated by marrying earlier and hence experiencing
an earlier age at first birth.
One possibility, then, is that the life-history trade-off
between growth and reproduction, which partially
seems to explain female stature and reproductive success,
may similarly affect male height. Selection seems
to favour a younger age at first birth in men, and this
may be tied to stature in a similar way as for women
(including phenotypic and genetic association between
height and age at first birth: Stearns et al., 2012). The
resulting curvilinear relationship of reproductive success
and height may therefore be a consequence of
both positive selection on height through, for example,
health, attractiveness and income, combined with negative
selection on height with respect to earlier age
at first birth. This is, however, purely speculative. In
addition to the relationship between growth and reproduction,
height also may be (genetically) correlated to
other traits under selection (Lande & Arnold, 1983).
Thus, the specific relationship between stature and
reproductive success may be a consequence of selection
on other traits related to height. Unfortunately, these
potential traits are not yet readily identified.
Another possibility that may account partially
for why average-height men attain higher reproductive
success, is that they not only by marry at
a younger age, but also reproduce with women
of higher reproductive potential. Although
shorter women prefer men much taller than
themselves, this does not equate to a preference
for tall men per se (Stulp et al., 2013a,b). Indeed, shorter
women tend to prefer men of average height. Similarly,
taller men prefer women who are shorter than they
are, but not necessarily short women. These specific
partner-height preferences in relation to one’s own
height may result in shorter women being more likely
to be paired to men of average height, rather than tall
men. There is some evidence to support this notion:
first, shorter women are most likely to match with
average-height men at speed-dating events (Stulp et al.,
2013a) and second, shorter women are more likely to
have average-height and shorter men as actual partners
than taller men (Stulp et al., 2013a,c). Thus, the
increased reproductive success of average-height men
compared to taller men may be a consequence of their
increased likelihood of pairing with shorter women,
who produce a larger number of children (Stulp et al.,
2012d).
Following this line of reasoning, one could then
argue that shorter men, who are also most likely to be
coupled to shorter women, should also have increased
reproductive success, but this is not the case. Reduced
reproductive success in shorter men may be a consequence
of other factors disfavouring short height,
such as lower health status and income, being less preferred
as a mate, and obtaining a mate of lesser quality.
Stulp et al. (2014) recently found support for these
predictions, with shorter men displaying a ‘double disadvantage’
in terms of both their own quality and that
of their spouses. In addition, Stulp et al. (2014) found
that differences in mate quality between average-height
and taller men were only marginal. Thus, the advantage
accruing to height seems to come simply from not
being short, rather than being taller than average.
Taken together, these findings suggest that the curvilinear
pattern between height and reproductive success
in contemporary USA populations is unlikely to be a
consequence of a single selection pressure, but is more
likely to be the result of competing pressures that act
differentially along the height continuum to produce
the observed effects on male reproductive success.
We should again stress that the above explanations
are purely speculative, and require thorough testing.
Moreover, we have no evidence to suggest that such
patterns extend beyond USA populations. As more and
better information of this nature becomes available,
it seems likely that a clearer picture of the manner
in which height translates into reproductive success
will arise. Even without a fully convincing explanation,
however, the contrast between the selection pressures
acting on female height and those acting on males in
contemporary USA populations is notable, and may
have a number of evolutionary consequences.
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
24 Gert Stulp and Louise Barrett
(c) Intralocus sexual conflict over height
The existence of contrasting selection pressures acting
on male and female height creates the potential
for intralocus sexual conflict (IASC). IASC arises when
there is differential selection on a trait for males and
females, but the genetic expression of a trait is determined
similarly in each sex (i.e. there is a strong intersexual
genetic correlation: Bonduriansky & Chenoweth,
2009). As a result, selection pressures in one sex constrain
the other from achieving its sex-specific fitness
optimum.
Given the high heritability of height in industrialized
populations (Silventoinen et al., 2001; Silventoinen,
2003) and the fact that tall parents produce tall sons and
tall daughters, and short parents produce short sons and
daughters, something along these lines may occur in
humans. That is, whether shorter or taller height is beneficial
depends on which sex expresses the trait (Rice
& Chippindale, 2001). Stulp et al. (2012b) addressed
this issue by investigating the reproductive success of
siblings in the same USA sample that revealed contrasting
selection pressures on the sexes. In short sibling
pairs, greater reproductive success accrued to the
female sibling compared to the male sibling, whereas
in average-height sibling pairs greater reproductive success
accrued to the male sibling compared to the female
sibling. Sexually antagonistic selection with respect to
height may, then, be a feature of the selective landscape
for some modern human populations.
Having said this, it is important to emphasize that the
existence of different phenotypic selection pressures
between the sexes is not sufficient to demonstrate IASC;
it is also necessary to show that the trait has significant
genetic variation, that there is a strongly positive intersexual
genetic correlation (i.e. such that independent
responses to selection by each sex will be constrained),
and that the genetic covariance between relative fitness
and the trait in question is positive in one sex but negative
in the other (Bolund et al., 2013). An evolutionary
response will only occur if at least part of the phenotypic
relationship between the trait and fitness has a genetic
basis (Morrissey et al., 2010). Stearns et al. (2012) found
that patterns of selection on height differed between
the sexes, with stabilizing selection on male height and
negative directional selection on female height, and
a positive cross-sex genetic covariance for this trait.
Despite these patterns, no significant genetic conflict
for height was apparent. Thus, it is possible that the population
studied by Stulp et al. (2012b) may show the same
effect, with phenotypic, but not genetic, sexual conflict.
(4) Is height a target of selection?
We are now in a position to attempt an answer to the
question of whether height is a trait of evolutionary significance,
with adaptive value of its own. There is some
evidence to suggest that variation in stature represents
an evolutionary adaptation to climatic conditions,
although the best current evidence suggests this applies
only in the Northern hemisphere. In most cases, the
evidence points to height variation as the expression
of an evolved reaction norm reflecting a life-history
trade-off between growth, maintenance and reproduction
(Walker et al., 2006). This is particularly true in
the case of women, where height derives much of its
evolutionary significance via processes relating to age
at first birth and infant survival. Among contemporary
populations, the lack of strong preferences among men
for female height also suggests that sexual selection
on height currently operating on women is unlikely to
be very strong. On balance then, in terms of selective
processes, natural selection acting on life-history events
seems more likely to explain variation in height among
women than sexual selection. At present, such inferences
remain largely speculative, however, given we
lack any studies that aim to test explicitly between these
alternative explanations. In addition, it is of course
possible that other non-selective evolutionary forces,
like drift, may play a role.
For men, it is also apparent that similar life-history
trade-offs to those that apply to women may also influence
stature in men, given cross-cultural relationships
between height and environmental quality that are
consistent with trade-offs between growth, maintenance
and reproduction (Walker et al., 2006). In addition,
there is some evidence to suggest that the link between
stature and greater reproductive success is indicative
of sexually-selected female choice for height (e.g.
Pawlowski et al., 2000; Mueller & Mazur, 2001). Indeed,
positive relationships between height, health, and various
measures of social status make it at least plausible
that height could be a target of selection. For certain
industrialized societies, however, where males of average
height are currently favoured by selection, this argument
cannot apply. In such cases, taller men are preferred
as partners, and are more economically successful
than those of shorter stature, yet show lower reproductive
success. Of course, this does not mean that sexual
selection for height did not operate in the past, and
present patterns cannot be used to infer past selection.
What we can say, however, is that the increased reproductive
success of average-height men in these populations
may be tied to their early age at first birth, which in
turn may be linked to an increased likelihood of pairing
with shorter women, who themselves have higher fitness
(Stulp et al., 2012d). Why, then, do taller men experience
a later age at first birth, particularly as they seem
favoured as mates? One possibility is that age at first
birth and stature may be tied to life-history trade-offs
similar to those found in women. Moreover, cultural
factors may promote slower life histories for taller men,
and they may enter the marriage market later than
their shorter counterparts. Currently, such explanations
remain speculative, and the association between male
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
Evolution and human height 25
stature and reproductive success across populations, as
is true for women, remains something of an enigma.
These results also have to be placed into a broader perspective,
as the curvilinear and negative relationships
between height and reproductive success come from a
limited number of Western societies, most of them in
the USA. As discussed above (Section II.2b), Americans
have been getting shorter, rather than taller, over the
past century; a finding that cannot be attributed purely
to increased levels of immigration (especially as the children
of immigrants grow very much taller than their
parents). The finding that selection consistently favours
both shorter female height and average male height
in this population fits well with this curious reversal in
height trends, but it also suggests that, given the ongoing
positive secular trend in other countries, particularly
the Netherlands, selection pressures in these populations
may well favour taller heights.
VII. CONCLUSIONS
(1) Although height is a trait that is easily measured
and data are widely available, it is apparent that we need
more consistent reporting of height across studies that
will allow for more rigorous and stringent tests of evolutionary
hypotheses, particularly those relating to sexual
dimorphism, Rensch’s rule and various aspects of life
history. Both major methodological differences among
studies and the various biases introduced by selection
criteria and sampling procedures mean it is difficult to
make any general statements about evolutionary pro-
cesses.
(2) There is evidence to suggest that natural selection
is acting on height in contemporary human populations,
and hence that differences across populations may
reflect more than just the expression of a flexible reaction
norm. Effect sizes are, however, low, which raises
the question of whether selection pressures are sufficiently
strong to explain the patterns seen. Theoretical
modelling is needed to help answer this question.
More empirical studies of height are needed to assess the
degree to which height is under selection in other populations,
and whether selection pressures differ. In addition,
such studies require large sample sizes and fewer
biases in inclusion criteria than those currently available,
and many existing studies require replication.
(3) Our understanding of, and attitudes toward, short
stature is clearly a vexed issue. While an evolutionary
approach considers it appropriate to view small bodies
as the result of life-history trade-offs, this does raise questions
of how this relates to adult health and socioeconomic
functioning, and whether we should view short
stature as adaptive or simply an accommodation to
poor conditions. Equally, however, we can question ideas
that ‘bigger is better’ should apply across the board,
and that shorter stature is always an indicator of poor
functioning, when viewed in a cross-cultural evolutionary
perspective. This issue, in particular, highlights the
fact that height cannot be considered as a purely biological
trait, but one that carries significant sociocultural
and political weight.
(4) Current trends relating to stature and sexual maturity
across industrialized countries present an unsolved
puzzle, and more and better individual-level data are
needed to test the life history hypotheses put forward
potentially to explain it.
(5) Work on the genetics of height has revealed that
it is a truly polygenic trait, to an even greater extent
than initially suspected. The advent of GWAS is making
it possible to trace the biological pathways that influence
height, and will help shed light on the links between
environmental conditions, growth trajectories, skeletal
maturity and the shift from growth to reproduction.
(6) For such a well-studied and easily measured trait,
there remain some surprising gaps in our knowledge
concerning the evolution and adaptive significance of
height. This suggests we should be cautious in our acceptance
of evolutionary (and specifically, adaptationist)
claims made about other human traits, particularly those
relating to our behaviour and psychology.
VIII. ACKNOWLEDGEMENTS
G.S. is supported by an NWO Rubicon fellowship, and
L.B. is supported by the NSERC Discovery Grant and
Canada Research Chair Programs. We thank Alexandre
Courtiol and an anonymous reviewer for their very
helpful and constructive comments that improved the
manuscript considerably. We are also extremely grateful
to Marcus Dostie and Tyler Bonnell for their help with
producing Fig. 1.
IX. REFERENCES
Abouheif, E. & Fairbairn, D. J. (1997). A comparative analysis of allometry for
sexual size dimorphism: assessing Rench’s rule. The American Naturalist 149,
540–562.
Ahmad, M., Gilbert, R. I. & Naqui, A.-U.-N. (1985). Assortative mating for
height in Pakistani arranged marriages. Journal of Biosocial Science 17, 211–214.
Alexander, R. D., Hoogland, J. L., Howard, R. D., Noonan, K. M. & Sherman,
P. W. (1979). Sexual dimorphism and breeding systems in pinnipeds, ungulates,
primates, and humans. In Evolutionary Biology and Human Social Behavior:
An Anthropological Perspective (eds N. A. Chagnon and W. Irons), pp. 402–435.
Duxbury Press, North Scituate.
Allen, J. A. (1877). The influence of physical conditions in the genesis of
species. Radical Review 1, 108–140.
Allen, H. L., Estrada, K., Lettre, G., Berndt, S. I., Weedon, M. N.,
Rivadeneira, F., Willer, C. J., Jackson, A. U., Vedantam, S. & Raychaudhuri,
S. (2010). Hundreds of variants clustered in genomic loci and biological
pathways affect human height. Nature 467, 832–838.
Antón, S. C. & Snodgrass, J. J. (2012). Origins and evolution of genus Homo.
Current Anthropology 53, S479–S496.
Archer, J. & Thanzami, V. (2009). The relation between mate value, entitlement,
physical aggression, size and strength among a sample of young Indian
men. Evolution and Human Behavior 30, 315–321.
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
26 Gert Stulp and Louise Barrett
Arendt, J. D. (1997). Adaptive intrinsic growth rates: an integration across taxa.
The Quarterly Review of Biology, 72, 149–177.
Bailey, S. M. & Garn, S. M. (1979). Socioeconomic interactions with physique
and fertility. Human Biology 51, 317–333.
Bailey, R. C., Head, G., Jenike, M., Owen, B., Rechtman, R. & Zechenter, E.
(1989). Hunting and gathering in tropical rain forest: is it possible? American
Anthropologist 91, 59–82.
Baqui, A. H., Arifeen, S. E., Amin, S. & Black, R. E. (1994). Levels and
correlates of maternal nutrional status in urban Bangladesh. European Journal
of Clinical Nutrition 48, 349–357.
Barker, D. & Clark, P. M. (1997). Fetal undernutrition and disease in later life.
Reviews of Reproduction 2, 105–112.
Barker, D., Osmond, C., Golding, J., Kuh, D. & Wadsworth, M. E. (1989).
Growth in utero, blood pressure in childhood and adult life, and mortality
from cardiovascular disease. British Medical Journal 298, 564–567.
Batty, G. D., Shipley, M. J., Gunnell, D., Huxley, R., Kivimaki, M., Woodward,
M., Lee, C. M. Y. & Smith, G. D. (2009). Height, wealth, and health: an
overview with new data from three longitudinal studies. Economics and Human
Biology 7, 137–152.
Beard, A. S. & Blaser, M. J. (2002). The ecology of height: the effect of
microbial transmission on human height. Perspectives in Biology and Medicine
45, 475–498.
Beaton, G. H. & Ghassemi, H. (1982). Supplementary feeding programs for
young children in developing countries. American Journal of Clinical Nutrition
35, 864–916.
Becker, N. S. A., Touraille, P., Froment, A., Heyer, E. & Courtiol, A. (2012).
Short stature in African pygmies is not explained by sexual selection. Evolution
and Human Behavior 33, 615–622.
Becker, N. S. A., Verdu, P., Froment, A., Le Bomin, S., Pagezy, H., Bahuchet,
S. & Heyer, E. (2011). Indirect evidence for the genetic determination of
short stature in African Pygmies. American Journal of Physical Anthropology 145,
390–401.
Becker, N. S., Verdu, P., Hewlett, B. & Pavard, S. (2010). Can life history
trade-offs explain the evolution of short stature in human pygmies? A response
to Migliano et al. (2007). Human Biology 82, 17–27.
de Beer, H. (2004). Observations on the history of Dutch physical stature from
the late-Middle Ages to the present. Economics and Human Biology 2, 45–55.
de Beer, H. (2012). Dairy products and physical stature: a systematic review and
meta-analysis of controlled trials. Economics and Human Biology 10, 299–309.
Bergmann, C. (1847). Über die Verhaltnisse der Warmeokonomie der Thiere
zu ihrer Grosse. Gottinger Studien 3, 595–708.
Bielicki, T. & Charzewski, J. (1983). Body height and upward social mobility.
Annals of Human Biology 10, 403–408.
Blum, M. (2013). The influence of inequality on the standard of living:
worldwide anthropometric evidence from the 19th and 20th centuries.
Economics and Human Biology 11, 436–452.
Bogin, B. (1999a). Evolutionary perspective on human growth. Annual Review
of Anthropology 28, 109–153.
Bogin, B. (1999a). Patterns of Human Growth. Cambridge University Press,
Cambridge.
Bogin, B. (2010). Evolution of human growth. In: Human Evolutionary Biology
(ed. M.P. Muehlenbein), pp. 379–395. Cambridge University Press,
Cambridge.
Bogin, B., Silva, M. I. V. & Rios, L. (2007). Life history trade-offs in human
growth: adaptation or pathology? American Journal of Human Biology 19,
631–642.
Bogin, B. A. & Smith, B. H. (1996). Evolution of the human life cycle. American
Journal of Human Biology 8, 703–716.
Bogin, B., Smith, P., Orden, A. B., Varela Silva, M. I. & Loucky, J. (2002).
Rapid change in height and body proportions of Maya American children.
American Journal of Human Biology 14, 753–761.
Bolund, E., Bouwhuis, S., Pettay, J. E. & Lummaa, V. (2013). Divergent
selection on, but no genetic conflict over, female and male timing and rate of
reproduction in a human population. Proceedings of the Royal Society B: Biological
Sciences 280, 20132002.
Bonduriansky, R. & Chenoweth, S. F. (2009). Intralocus sexual conflict. Trends
in Ecology & Evolution 24, 280–288.
Bozzoli, C., Deaton, A. & Quintana-Domeque, C. (2009). Adult height and
childhood disease. Demography 46, 647–669.
Brace, C. L. & Ryan, A. S. (1980). Sexual dimorphism and human tooth size
differences. Journal of Human Evolution 9, 417–435.
Bramble, D. M. & Lieberman, D. E. (2004). Endurance running and the
evolution of Homo. Nature 432, 345–352.
Brauer, G. W. (1982). Size sexual dimorphism and secular trend: indicators of
subclinical malnutrition? In Sexual Dimorphism in Homo Sapiens: A Question of
Size (ed. R. L. Hall), pp. 245–259. Praeger, New York.
Bresler, J. B. (1962). Maternal height and the prevalence of stillbirths. American
Journal of Physical Anthropology 20, 515–517.
Brush, G., Boyce, A. J. & Harrison, G. A. (1983). Associations between
anthropometric variables and reproductive performance in a Papua New
Guinea highland population. Annals of Human Biology 10, 223–234.
Burger, O., DeLong, J. P. & Hamilton, M. J. (2011). Industrial energy use and
the human life history. Scientific Reports 1, 1–7.
Butt, L. (1999). Measurements, morality, and the politics of ‘normal’ infant
growth. Journal of Medical Humanities 20, 81–100.
Byars, S. G., Ewbank, D., Govindaraju, D. R. & Stearns, S. C. (2010). Natural
selection in a contemporary human population. Proceedings of the National
Academy of Sciences of the United States of America 107, 1787–1792.
Camilleri, A. P. (1981). The obstetric significance of short stature. European
Journal of Obstetrics & Gynecology and Reproductive Biology 12, 347–356.
Case, A. & Paxson, C. (2006). Stature and status: height, ability, and labor
market outcomes. National Bureau of Economic Research.
Casey, B. M., McIntire, D. D. & Leveno, K. J. (2001). The continuing value of
the Apgar score for the assessment of newborn infants. New England Journal of
Medicine 344, 467–471.
Cavalli-Sforza, L. L. (1986). African Pygmies. Academic Press, New York.
Cavelaars, A., Kunst, A. E., Geurts, J., Crialesi, R., Grötvedt, L., Helmert,
U., Lahelma, E., Lundberg, O., Mielck, A. & Rasmussen, N. K. (2000).
Persistent variations in average height between countries and between
socio-economic groups: an overview of 10 European countries. Annals of
Human Biology 27, 407–421.
Cawley, J., Joyner, K. & Sobal, J. (2006). Size matters the influence of
adolescents’ weight and height on dating and sex. Rationality and Society 18,
67–94.
Cernerud, L. (1995). Height and social mobility: a study of the height of 10 year
olds in relation to socio-economic background and type of formal schooling.
Scandinavian Journal of Public Health 23, 28–31.
Charmantier, A. & Garant, D. (2005). Environmental quality and evolutionary
potential: lessons from wild populations. Proceedings of the Royal Society B:
Biological Sciences 272, 1415–1425.
Charnov, E. L. (1991). Evolution of life history variation among female
mammals. Proceedings of the National Academy of Sciences of the United States of
America 88, 1134–1137.
Charnov, E. L. (1993). Life History Invariants: Some Explorations of Symmetry in
Evolutionary Ecology. Oxford University Press, Oxford.
Cho, Y. S., Go, M. J., Kim, Y. J., Heo, J. Y., Oh, J. H., Ban, H.-J., Yoon, D., Lee, M.
H., Kim, D.-J. & Park, M. (2009). A large-scale genome-wide association study
of Asian populations uncovers genetic factors influencing eight quantitative
traits. Nature Genetics 41, 527–534.
Cinnirella, F., Piopiunik, M. & Winter, J. (2011). Why does height matter
for educational attainment? Evidence from German children. Economics and
Human Biology 9, 407–418.
Cinnirella, F. & Winter, J. (2009). Size matters! Body height and labor market
discrimination: a cross-European analysis. CESifo Working Paper Series,
1–29.
Clark, P. J. & Spuhler, J. N. (1959). Differential fertility in relation to body
dimensions. Human Biology 31, 121–137.
Cole, T. J. (2000). Secular trends in growth. Proceedings of the Nutrition Society 59,
317–324.
Cole, T. J. (2003). The secular trend in human physical growth: a biological
view. Economics and Human Biology 1, 161–168.
Courtiol, A., Picq, S., Godelle, B., Raymond, M. & Ferdy, J. B. (2010a). From
preferred to actual mate characteristics: the case of human body shape. PLoS
ONE 5, e13010.
Courtiol, A., Raymond, M., Godelle, B. & Ferdy, J. B. (2010b). Mate choice
and human stature: homogamy as a unified framework for understanding
mating preferences. Evolution 64, 2189–2203.
Courtiol, A., Rickard, I. J., Lummaa, V., Prentice, A. M., Fulford, A. J. C.
& Stearns, S. C. (2013). The demographic transition influences variance
infitness and selection on height and BMI in rural Gambia. Current Biology
23, 884–889.
Damon, A. & Thomas, R. B. (1967). Fertility and physique-height, weight and
ponderal index. Human Biology 39, 5–13.
Danubio, M. E. & Sanna, E. (2008). Secular changes in human biological
variables in Western countries: an updated review and synthesis. Journal of
Anthropological Science 86, 91–112.
Darwin, C. (1871). The Descent of Man and Selection in Relation to Sex. John
Murray, London.
Dávila, N., Shea, B. T., Omoto, K., Mercado, M., Misawa, S. & Baumann,
G. (2002). Growth hormone binding protein, insulin-like growth factor-I
and short stature in two pygmy populations from the Philippines. Journal of
Pediatric Endocrinology and Metabolism 15, 269–276.
Day, T. & Rowe, L. (2002). Developmental thresholds and the evolution
of reaction norms for age and size at life-history transitions. The American
Naturalist 159, 338–350.
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
Evolution and human height 27
Deady, D. K. & Law Smith, M. J. (2006). Height in women predicts maternal
tendencies and career orientation. Personality and Individual Differences 40,
17–25.
Deaton, A. (2007). Height, health, and development. Proceedings of the National
Academy of Sciences of the United States of America 104, 13232–13237.
Deaton, A. & Arora, R. (2009). Life at the top: the benefits of height. Economics
and Human Biology 7, 133–136.
De Onis, M., Monteiro, C., Akré, J. & Clugston, G. (1993). The worldwide
magnitude of protein-energy malnutrition: an overview from the WHO Global
Database on child growth. Bulletin of the World Health Organization 71, 703–712.
Devi, M. R., Kumari, J. R. & Srikumari, C. R. (1985). Fertility and mortality
differences in relation to maternal body size. Annals of Human Biology 12,
479–484.
Diamond, J. M. (1991). Anthropology. Why are pygmies small? Nature 354, 111.
Dowd, J. B., Zajacova, A. & Aiello, A. (2009). Early origins of health disparities:
burden of infection, health, and socioeconomic status in US children. Social
Science & Medicine 68, 699–707.
Edozien, J. C., Khan, M. R. & Waslien, C. I. (1976). Human protein deficiency:
results of a Nigerian village study. The Journal of Nutrition 106, 312–328.
Elks, C. E., Perry, J. R., Sulem, P., Chasman, D. I., Franceschini, N., He, C.,
Lunetta, K. L., Visser, J. A., Byrne, E. M. & Cousminer, D. L. (2010). Thirty
new loci for age at menarche identified by a meta-analysis of genome-wide
association studies. Nature Genetics 42, 1077–1085.
Ellis, L. (1994). The high and the mighty among man and beast: how universal
is the relationship between height (or body size) and social status. In Social
Stratification and Socioeconomic Inequality (Volume 2), pp. 93–112. Praeger
Publishers, Connecticut.
Ellison, P. T. (1982). Skeletal growth, fatness, and menarcheal age: a comparison
of two hypotheses. Human Biology 54, 269–281.
Ellison, P. T. (1990). Human ovarian function and reproductive ecology: new
hypotheses. American Anthropologist 92, 933–952.
Ellison, P. T. (2001). Reproductive Ecology and Human Evolution. Transaction
Publishers, New York.
Ellison, P. T. (2009). On Fertile Ground: A Natural History of Human Reproduction.
Harvard University Press, Cambridge.
Ellison, P. T. & Jasienska, G. (2007). Constraint, pathology, and adaptation:
how can we tell them apart? American Journal of Human Biology 19, 622–630.
Fairbairn, D. J. (1997). Allometry for sexual size dimorphism: pattern and
process in the coevolution of body size in males and females. Annual Review of
Ecology and Systematics 28, 659–687.
Fairbairn, D. J., Blanckenhorn, W. U. & Székely, T. (2007). Sex, Size, and
Gender Roles: Evolutionary Studies of Sexual Size Dimorphism. Oxford University
Press, Oxford.
Fielding, R., Schooling, C. M., Adab, P., Cheng, K. K., Lao, X. Q., Jiang, C.
Q. & Lam, T. H. (2008). Are longer legs associated with enhanced fertility in
Chinese women? Evolution and Human Behavior 29, 434–443.
Fink, B., Neave, N., Brewer, G. & Pawlowski, B. (2007). Variable preferences
for sexual dimorphism in stature (SDS): further evidence for an adjustment
in relation to own height. Personality and Individual Differences 43, 2249–2257.
Fisher, R. A. (1918). XV.—The correlation between relatives on the supposition
of mendelian inheritance. Transactions of the Royal Society of Edinburgh 52,
399–433.
Floud, R., Fogel, R. W., Harris, B. & Hong, S. C. (2011). The Changing Body.
Cambridge University Press, Cambridge.
Foster, F. & Collard, M. (2013). A reassessment of Bergmann’s rule in modern
humans. PLoS ONE 8, e72269.
Fox, C. W. & Westneat, D. F. (2010). Adaptation. In Evolutionary Behavioral
Ecology (eds D. F. Westneat and C. W. Fox), pp. 16–31. Oxford University
Press, New York.
Frayer, D. W. (1980). Sexual dimorphism and cultural evolution in the late
Pleistocene and Holocene of Europe. Journal of Human Evolution 9, 399–415.
Frayer, D. W. (1981). Body size, weapon use, and natural selection in the European
Upper Paleolithic and Mesolithic. American Anthropologist 83, 57–73.
Frayer, D. W. & Wolpoff, M. H. (1985). Sexual dimorphism. Annual Review of
Anthropology 14, 429–473.
Fredriks, A. M., van Buuren, S., Burgmeijer, R. J., Meulmeester, J. F.,
Beuker, R. J., Brugman, E., Roede, M. J., Verloove-Vanhorick, S. P. & Wit,
J.-M. (2000). Continuing positive secular growth change in The Netherlands
1955–1997. Pediatric Research 47, 316–323.
Gallagher, A. (2013). Stature, body mass, and brain size: a two-million-year
odyssey. Economics and Human Biology 11, 551–562.
Galton, F. (1886). Regression towards mediocrity in hereditary stature. The
Journal of the Anthropological Institute of Great Britain and Ireland 15, 246–263.
Garcia, J. & Quintana-Domeque, C. (2007). The evolution of adult height in
Europe: a brief note. Economics and Human Biology 5, 340–349.
Gaulin, S. & Boster, J. (1985). Cross-cultural differences in sexual dimorphism:
is there any variance to be explained? Ethology and Sociobiology 6, 219–225.
Gaulin, S. J. & Boster, J. S. (1992). Human marriage systems and sexual
dimorphism in stature. American Journal of Physical Anthropology 89, 467–475.
Geist, V. (1987). Bergmann’s rule is invalid. Canadian Journal of Zoology 65,
1035–1038.
Genovese, J. E. C. (2008). Physique correlates with reproductive success in an
archival sample of delinquent youth. Evolutionary Psychology 6, 369–385.
Gillis, J. S. & Avis, W. E. (1980). The male-taller norm in mate selection.
Personality and Social Psychology Bulletin 6, 396–401.
Gluckman, P. D. & Hanson, M. A. (2006). Evolution, development and timing
of puberty. Trends in Endocrinology & Metabolism 17, 7–12.
Gluckman, P. D., Hanson, M. A. & Spencer, H. G. (2005). Predictive adaptive
responses and human evolution. Trends in Ecology & Evolution 20, 527–533.
Godoy, R., Eisenberg, D. T. A., Reyes-García, V., Huanca, T., Leonard, W.
R., McDade, T. W. & Tanner, S. (2008). Assortative mating and offspring
well-being: theory and empirical findings from a native Amazonian society
in Bolivia. Evolution and Human Behavior 29, 201–210.
Goldstein, M. S. & Kobyliansky, E. (1984). Anthropometric traits, balanced
selection and fertility. Human Biology 56, 35–46.
Graves, R. R., Lupo, A. C., McCarthy, R. C., Wescott, D. J. & Cunningham, D.
L. (2010). Just how strapping was KNM-WT 15000? Journal of Human Evolution
59, 542–554.
Gray, P. (2013). Hunter-gatherer egalitarianism as a force for decline in sexual
dimorphism. Psychological Inquiry 24, 192–194.
Gray, J. P. & Wolfe, L. D. (1980). Height and sexual dimorphism of stature
among human societies. American Journal of Physical Anthropology 53, 441–456.
Griffiths, P. E. & Gray, R. D. (1994). Developmental systems and evolutionary
explanation. The Journal of Philosophy 91, 277–304.
Griffiths, P. E. & Gray, R. D. (2001). Darwinism and developmental systems.
In Cycles of Contingency: Developmental Systems and Evolution, (eds. S. Oyama,
R.D. Gray & P.E. Griffiths) pp. 195–218. MIT Press, Cambridge (Mass.).
Guegan, J. F., Teriokhin, A. T. & Thomas, F. (2000). Human fertility variation,
size-related obstetrical performance and the evolution of sexual stature
dimorphism. Proceedings of the Royal Society B: Biological Sciences 267, 2529–2535.
Gustafsson, A. & Lindenfors, P. (2004). Human size evolution: no evolutionary
allometric relationship between male and female stature. Journal of Human
Evolution 47, 253–266.
Gustafsson, A. & Lindenfors, P. (2009). Latitudinal patterns in human stature
and sexual stature dimorphism. Annals of Human Biology 36, 74–87.
Gustafsson, A., Werdelin, L., Tullberg, B. S. & Lindenfors, P. (2007).
Stature and sexual stature dimorphism in Sweden, from the 10th to the end
of the 20th century. American Journal of Human Biology 19, 861–870.
Hadley, C. & Hruschka, D. J. (2014). Population level differences in adult body
mass emerge in infancy and early childhood: evidence from a global sample of
low and lower-income countries. American Journal of Physical Anthropology 154,
232–238.
Hamilton, M. E. (1982). Sexual dimorphism in skeletal samples. In Sexual
Dimorphism in Homo Sapiens, pp. 107–163. Praeger, New York.
Harper, B. (2000). Beauty, stature and the labour market: a British cohort study.
Oxford Bulletin of Economics and Statistics 62, 771–800.
Harvey, P. H. & Bennett, P. M. (1985). Sexual dimorphism and reproductive
strategies. In Human Sexual Dimorphism, pp. 43–59. Taylor and Francis,
London.
Harvey, P. H. & Clutton-Brock, T. H. (1985). Life history variation in
primates. Evolution 39, 559–581.
Harvey, P. H. & Purvis, A. (1999). Understanding the ecological and evolutionary
reasons for life history variation: mammals as a case study. In Advanced
Ecological Theory: Principles and Applications, Blackwell Science, Oxford. pp.
232–248.
Harvey, P. H. & Zammuto, R. M. (1985). Patterns of mortality and age at first
reproduction in natural populations of mammals. Nature 315, 319–320.
Hatton, T. J. (2013). How have Europeans grown so tall? Oxford Economic Papers
2, 349–372.
Hatton, T. J. & Martin, R. M. (2010). Fertility decline and the heights of
children in Britain, 1886–1938. Explorations in Economic History 47, 505–519.
Hauspie, R., Vercauteren, M. & Susanne, C. (1996). Secular changes in
growth. Hormone Research in Pædiatrics 45, 8–17.
Hauspie, R. C., Vercauteren, M. & Susanne, C. (1997). Secular changes in
growth and maturation: an update. Acta Paediatrica 86, 20–27.
Helle, S. (2008). A tradeoff between reproduction and growth in contemporary
Finnish women. Evolution and Human Behavior 29, 189–195.
Henneberg, M., Harrison, G. A. & Brush, G. (1998). The small child:
anthropometric and physical performance characteristics of short-for-age
children growing in good and in poor socio-economic conditions. European
Journal of Clinical Nutrition 52, 286–291.
Herpin, N. (2005). Love, careers, and heights in France, 2001. Economics and
Human Biology 3, 420–449.
Hiernaux, J. (1968). Ethnic differences in growth and development. Biodemography
and Social Biology 15, 12–21.
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
28 Gert Stulp and Louise Barrett
Holden, C. & Mace, R. (1999). Sexual dimorphism in stature and women’s
work: a phylogenetic cross-cultural analysis. American Journal of Physical Anthropology
110, 27–45.
Huang, W., Olson, J. S. & Olson, G. M. (2002). Camera angle affects dominance
in video-mediated communication. In Proceedings of the Conference
on Human Factors in Computing Systems, pp. 716–717. Association for Computing
Machinery, New York.
Hur, Y.-M. (2003). Assortative mating for personality traits, educational level,
religious affiliation, height, weight, and body mass index in parents of a
Korean twin sample. Twin Research 6, 467–470.
Jarvis, J. P., Scheinfeldt, L. B., Soi, S., Lambert, C., Omberg, L., Ferwerda,
B., Froment, A., Bodo, J.-M., Beggs, W. & Hoffman, G. (2012). Patterns of
ancestry, signatures of natural selection, and genetic association with stature
in Western African pygmies. PLoS Genetics 8, e1002641.
Judge, T. A. & Cable, D. M. (2004). The effect of physical height on workplace
success and income: preliminary test of a theoretical model. Journal of Applied
Psychology 89, 428–441.
Katzmarzyk, P. T. & Leonard, W. R. (1998). Climatic influences on human
body size and proportions: ecological adaptations and secular trends. American
Journal of Physical Anthropology 106, 483–503.
Kim, Y. S. (1982). Growth status of Korean schoolchildren in Japan. Annals of
Human Biology 9, 453–458.
Kingsolver, J. G., Hoekstra, H. E., Hoekstra, J. M., Berrigan, D., Vignieri,
S. N., Hill, C. E., Hoang, A., Gibert, P. & Beerli, P. (2001). The strength
of phenotypic selection in natural populations. The American Naturalist 157,
245–261.
Kirchengast, S. (2000). Differential reproductive success and body size in
!Kung San people from northern Namibia. Collegium Antropologicum 24,
121–132.
Kirchengast, S. & Hartmann, B. (2007). Short stature is associated with an
increased risk of caesarean deliveries in low risk population. Acta Medica
Lituanica 14, 1–6.
Kirchengast, S. & Winkler, E. M. (1995). Differential reproductive success
and body dimensions in Kavango males from urban and rural-Areas in
northern Namibia. Human Biology 67, 291–309.
Kirchengast, S. & Winkler, E. M. (1996). Differential fertility and body build
in !Kung San and Kavango females from northern Namibia. Journal of Biosocial
Science 28, 193–210.
Komlos, J. & Baur, M. (2004). From the tallest to (one of) the fattest: the
enigmatic fate of the American population in the 20th century. Economics and
Human Biology 2, 57–74.
Kramer, K. L. & Greaves, R. D. (2010). Synchrony between growth and
reproductive patterns in human females: early investment in growth among
Pumé foragers. American Journal of Physical Anthropology, 235–244.
Krams, I. A., Skrinda, I., Kecko, S., Moore, F. R., Krama, T., Kaasik, A., Meija,
L., Lietuvietis, V. & Rantala, M. J. (2014). Body height affects the strength
of immune response in young men, but not young women. Scientific Reports 4,
Article Number 6223.
Krzy ̇zanowska, M. & Mascie-Taylor, C. N. (2011). Intra-and intergenerational
social mobility in relation to height, weight and body mass index in
a British national cohort. Journal of Biosocial Science 43, 611–618.
Kuijper, B., Pen, I. & Weissing, F. J. (2012). A guide to sexual selection theory.
Annual Review of Ecology, Evolution, and Systematics 43, 287–311.
Kurki, H. K. (2007). Protection of obstetric dimensions in a small-bodied
human sample. American Journal of Physical Anthropology 133, 1152–1165.
Kurki, H. K. (2011). Pelvic dimorphism in relation to body size and body size
dimorphism in humans. Journal of Human Evolution 61, 631–643.
Kurki, H. K. (2013). Bony pelvic canal size and shape in relation to body
proportionality in humans. American Journal of Physical Anthropology 151,
88–101.
Kurzban, R. & Weeden, J. (2007). Do advertised preferences predict the
behavior of speed daters? Personal Relationships 14, 623–632.
Kuzawa, C. W. (2007). Developmental origins of life history: growth, productivity,
and reproduction. American Journal of Human Biology 19, 654–661.
Lande, R. & Arnold, S. J. (1983). The measurement of selection on correlated
characters. Evolution 37, 1210–1226.
Langley-Evans, S. C. (2006). Developmental programming of health and
disease. The Proceedings of the Nutrition Society 65, 97–105.
Larsen, C. S. (1995). Biological changes in human populations with agriculture.
Annual Review of Anthropology 24, 185–213.
Lasker, G. W. & Thomas, R. (1976). Relationship between reproductive fitness
and anthropometric dimensions in a Mexican population. Human Biology 48,
775–791.
Lawson, D. W. & Mace, R. (2008). Sibling configuration and childhood growth
in contemporary British families. International Journal of Epidemiology 37,
1408–1421.
Leigh, S. R. (2001). Evolution of human growth. Evolutionary Anthropology: Issues,
News, and Reviews 10, 223–236.
Leighton, G. & Clark, M. L. (1929). Milk consumption and the growth of
school children: second preliminary report on tests to the Scottish Board of
Health. British Medical Journal 1, 23–25.
Lettre, G. (2011). Recent progress in the study of the genetics of height. Human
Genetics 129, 465–472.
Li, M.-X., Liu, P.-Y., Li, Y.-M., Qin, Y.-J., Liu, Y.-Z. & Deng, H.-W. (2004). A major
gene model of adult height is suggested in Chinese. Journal of Human Genetics
49, 148–153.
Liestøl, K. & Rosenberg, M. (1995). Height, weight and menarcheal age of
schoolgirls in Oslo-an update. Annals of Human Biology 22, 199–205.
Liu, F., Hendriks, A. E. J., Ralf, A., Boot, A. M., Benyi, E., Sävendahl, L.,
Oostra, B. A., Duijn, C., Hofman, A., Rivadeneira, F., Uitterlinden, A.
G., Drop, S. L. S. & Kayser, M. (2013). Common DNA variants predict tall
stature in Europeans. Human Genetics 133, 587–597.
Lordkipanidze, D., Jashashvili, T., Vekua, A., de León, M. S. P., Zollikofer,
C. P. E., Rightmire, G. P., Pontzer, H., Ferring, R., Oms, O., Tappen, M.,
Bukhsianidze, M., Agusti, J., Kahlke, R., Kiladze, G., Martinez-Navarro,
B., Mouskhelishvili, A., Nioradze, M. & Rook, L. (2007). Postcranial
evidence from early Homo from Dmanisi, Georgia. Nature 449, 305–310.
Luke, A., Guo, X., Adeyemo, A. A., Wilks, R., Forrester, T., Lowe, W. Jr.,
Comuzzie, A. G., Martin, L. J., Zhu, X. & Rotimi, C. N. (2001). Heritability
of obesity-related traits among Nigerians, Jamaicans and US black people.
International Journal of Obesity 25, 1034–1041.
Magnusson, P. K., Rasmussen, F. & Gyllensten, U. B. (2006). Height at age
18 years is a strong predictor of attained education later in life: cohort study
of over 950 000 Swedish men. International Journal of Epidemiology 35, 658–663.
Malina, R. M. (2004). Secular trends in growth, maturation and physical
performance: a review. Anthropology Review 67, 3–31.
Malina, R. M., Pena Reyes, M. E., Tan, S. K., Buschang, P. H., Little, B. B.
& Koziel, S. (2004). Secular change in height, sitting height and leg length
in rural Oaxaca, southern Mexico: 1968–2000. Annals of Human Biology 31,
615–633.
Malina, R. M., Selby, H. A., Buschang, P. H., Aronson, W. L. & Little,
B. B. (1983). Assortative mating for phenotypic characteristics in a Zapotec
community in Oaxaca, Mexico. Journal of Biosocial Science 15, 273–280.
Manfredini, M., Breschi, M., Fornasin, A. & Seghieri, C. (2013). Height,
socioeconomic status and marriage in Italy around 1900. Economics and Human
Biology 11, 465–473.
Marsh, A. A., Henry, H. Y., Schechter, J. C. & Blair, R. (2009). Larger than
life: humans’ nonverbal status cues alter perceived size. PLoS ONE 4, e5707.
Martorell, R., Delgado, H. L., Delgado, H., Valverde, V. & Klein, R. E.
(1981). Maternal stature, fertility and infant mortality. Human Biology 53,
303–312.
Mascie-Taylor, C. G. (1991). Biosocial influences on stature: a review. Journal
of Biosocial Science 23, 113–128.
McEvoy, B. P. & Visscher, P. M. (2009). Genetics of human height. Economics
and Human Biology 7, 294–306.
McIntire, D. D., Bloom, S. L., Casey, B. M. & Leveno, K. J. (1999). Birth weight
in relation to morbidity and mortality among newborn infants. New England
Journal of Medicine 340, 1234–1238.
McIntyre, M. H. & Kacerosky, P. M. (2011). Age and size at maturity in women:
a norm of reaction? American Journal of Human Biology 23, 305–312.
McManus, I. C. & Mascie-Taylor, C. (1984). Human assortative mating for
height: non-linearity and heteroscedasticity. Human Biology 56, 617–623.
Metcalfe, N. B. & Monaghan, P. (2001). Compensation for a bad start: grow
now, pay later? Trends in Ecology & Evolution 16, 254–260.
Migliano, A. B., Vinicius, L. & Lahr, M. M. (2007). Life history trade-offs
explain the evolution of human pygmies. Proceedings of the National Academy
of Sciences of the United States of America 104, 20216–20219.
Migliano, A. B., Vinicius, L. & Lahr, M. M. (2010). Why are pygmies so short?
A defense of Migliano’s hypothesis. Human Biology 82, 109–113.
Mitton, J. B. (1975). Fertility differentials in modern societies resulting in
normalizing selection for height. Human Biology 47, 189–200.
Monaghan, P. (2008). Early growth conditions, phenotypic development and
environmental change. Philosophical Transactions of the Royal Society of London.
Series B, Biological Sciences 363, 1635–1645.
Monden, C. W. & Smits, J. (2009). Maternal height and child mortality in 42
developing countries. American Journal of Human Biology 21, 305–311.
Moorad, J. A. & Promislow, D. E. L. (2010). Evolution: aging up a tree? Current
Biology 20, R406–R408.
Morabia, A. & Costanza, M. C. (1998). International variability in ages
at menarche, first livebirth, and menopause. World Health Organization
Collaborative Study of Neoplasia and Steroid Contraceptives. American Journal
of Epidemiology 148, 1195–1205.
Morrissey, M. B., Kruuk, L. E. B. & Wilson, A. J. (2010). The danger of applying
the breeder’s equation in observational studies of natural populations.
Journal of Evolutionary Biology 23, 2277–2288.
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
Evolution and human height 29
Moss, E. G., Lee, R. C. & Ambros, V. (1997). The cold shock domain protein
LIN-28 controls developmental timing in C. elegans and is regulated by the
lin-4 RNA. Cell 88, 637–646.
Mueller, W. H. (1979). Fertility and physique in a malnourished population.
Human Biology 51, 153–166.
Mueller, W. H., Lasker, G. W. & Evans, F. G. (1981). Anthropometric
measurements and Darwinian fitness. Journal of Biosocial Science 13, 309–316.
Mueller, U. & Mazur, A. (2001). Evidence of unconstrained directional
selection for male tallness. Behavioral Ecology and Sociobiology 50, 302–311.
Mummert, A., Esche, E., Robinson, J. & Armelagos, G. J. (2011). Stature and
robusticity during the agricultural transition: evidence from the bioarchaeological
record. Economics and Human Biology 9, 284–301.
Nenko, I. & Jasienska, G. (2009). Fertility, body size, and shape: an empirical
test of the covert maternal depletion hypothesis. American Journal of Human
Biology 21, 520–523.
Nettle, D. (2002a). Height and reproductive success in a cohort of British men.
Human Nature 13, 473–491.
Nettle, D. (2002b). Women’s height, reproductive success and the evolution
of sexual dimorphism in modern humans. Proceedings of the Royal Society B:
Biological Sciences 269, 1919–1923.
Oreffice, S. & Quintana-Domeque, C. (2010). Anthropometry and socioeconomics
among couples: evidence in the United States. Economics and Human
Biology 8, 373–384.
Orr, J. B. (1928). Milk consumption and the growth of school children:
preliminary report on tests to the Scottish Board of Health. The Lancet 211,
202–203.
Oyama, S., Griffiths, P. E. & Gray, R. D. (2001). Cycles of Contingency:
Developmental Systems and Evolution. MIT Press, Cambridge.
Özaltin, E., Hill, K. & Subramanian, S. V. (2010). Association of maternal
stature with offspring mortality, underweight, and stunting in low-to
middle-income countries. JAMA 303, 1507–1516.
Pawlowski, B. (2003). Variable preferences for sexual dimorphism in height as
a strategy for increasing the pool of potential partners in humans. Proceedings
of the Royal Society B: Biological Sciences 270, 709–712.
Pawlowski, B., Dunbar, R. & Lipowicz, A. (2000). Evolutionary fitness: tall
men have more reproductive success. Nature 403, 156.
Peck, A. N. (1992). Childhood environment, intergenerational mobility, and
adult health--evidence from Swedish data. Journal of Epidemiology and Community
Health 46, 71–74.
Peck, M. N. & Lundberg, O. (1995). Short stature as an effect of economic and
social conditions in childhood. Social Science & Medicine 41, 733–738.
Pelto, G. H. & Pelto, P. J. (1989). Small but healthy? An anthropological
perspective. Human Organization 48, 11–15.
Perola, M., Sammalisto, S., Hiekkalinna, T., Martin, N. G., Visscher, P.
M., Montgomery, G. W., Benyamin, B., Harris, J. R., Boomsma, D. &
Willemsen, G. (2007). Combined genome scans for body stature in 6,602
European twins: evidence for common Caucasian loci. PLoS Genetics 3, e97.
Perry, G. H. & Dominy, N. J. (2009). Evolution of the human pygmy phenotype.
Trends in Ecology & Evolution 24, 218–225.
Perry, G. H., Foll, M., Grenier, J.-C., Patin, E., Nédélec, Y., Pacis,
A., Barakatt, M., Gravel, S., Zhou, X., Nsobya, S.L., Excoffier, L.,
Quintana-Murci, L, Dominy, N.J. & Barreiro, L.B. (2014). Adaptive,
convergent origins of the Pygmy phenotype in African rainforest
hunter-gatherers. Proceedings of the National Academy of Sciences 111,
E3596–E3603.
Persico, N., Postlewaite, A. & Silverman, D. (2004). The effect of adolescent
experience on labor market outcomes: the case of height. National Bureau of
Economic Research.
Pieper, U. (1981). Assortative mating in the population of a German and a
Cameroon city. Journal of Human Evolution 10, 643–645.
Pierce, C. A. (1996). Body height and romantic attraction: a meta-analytic test
of the male-taller norm. Social Behavior and Personality: An International Journal
24, 143–149.
Plavcan, J. M. (2011). Understanding dimorphism as a function of changes in
male and female traits. Evolutionary Anthropology 20, 143–155.
Plavcan, J. M. (2012). Sexual size dimorphism, canine dimorphism, and
male-male competition in primates. Human Nature 23, 45–67.
Pollet, T. V. & Nettle, D. (2008). Taller women do better in a stressed
environment: height and reproductive success in rural Guatemalan women.
American Journal of Human Biology 20, 264–269.
Pontzer, H. (2012). Ecological energetics in early Homo. Current Anthropology
53, S346–S358.
Promislow, D. E. & Harvey, P. H. (1990). Living fast and dying young:
a comparative analysis of life-history variation among mammals. Journal of
Zoology 220, 417–437.
Puts, D. A. (2010). Beauty and the beast: mechanisms of sexual selection in
humans. Evolution and Human Behavior 31, 157–175.
Rice, W. R. & Chippindale, A. K. (2001). Intersexual ontogenetic conflict.
Journal of Evolutionary Biology 14, 685–693.
Roberts, D. F. (1953). Body weight, race and climate. American Journal of Physical
Anthropology 11, 533–558.
Roberts, D. F. (1978). Climate and Human Variability. Second Edition. Cummings
Publishing Company, Menlo Park.
Roff, D. A. (1992). Evolution of Life Histories: Theory and Analysis. Chapman &
Hall, London.
Rogers, A. R. & Mukherjee, A. (1992). Quantitative genetics of sexual
dimorphism in human body size. Evolution 46, 226–234.
Rona, R. J., Swan, A. V. & Altman, D. G. (1978). Social factors and height of
primary schoolchildren in England and Scotland. Journal of Epidemiology and
Community Health 32, 147–154.
von Rueden, C., Gurven, M. & Kaplan, H. (2008). The multiple dimensions of
male social status in an Amazonian society. Evolution and Human Behavior 29,
402–415.
Ruff, C. (1987). Sexual dimorphism in human lower limb bone structure:
relationship to subsistence strategy and sexual division of labor. Journal of
Human Evolution 16, 391–416.
Ruff, C. B. (1991). Climate and body shape in hominid evolution. Journal of
Human Evolution 21, 81–105.
Ruff, C. B. (1993). Climatic adaptation and hominid evolution: the thermoregulatory
imperative. Evolutionary Anthropology: Issues, News, and Reviews 2, 53–60.
Ruff, C. B. (1994). Morphological adaptation to climate in modern and fossil
hominids. American Journal of Physical Anthropology 37, 65–107.
Ruff, C. (2002). Variation in human body size and shape. Annual Review of
Anthropology 31, 211–232.
Ruff, C. (2010). Body size and body shape in early hominins – implications of
the Gona Pelvis. Journal of Human Evolution 58, 166–178.
Ruff, C. B., Trinkaus, E. & Holliday, T. W. (1997). Body mass and encephalization
in Pleistocene Homo. Nature 387, 173–176.
Ruff, C. B. & Walker, A. (1993). Body size and shape. In The Nariokotome
Homo Erectus Skeleton (eds A. Walker and R. Leakey), pp. 234–265. Harvard
University Press, Cambridge.
Salska, I., Frederick, D. A., Pawlowski, B., Reilly, A. H., Laird, K. T. & Rudd,
N. A. (2008). Conditional mate preferences: factors influencing preferences
for height. Personality and Individual Differences 44, 203–215.
Samaras, T. T. (2009). Should we be concerned over increasing body height and
weight? Experimental Gerontology 44, 83–92.
Schönbeck, Y., Talma, H., van Dommelen, P., Bakker, B., Buitendijk, S.E.,
Hirasing, R.A. & van Buuren, S. (2012) The World’s Tallest Nation Has
Stopped Growing Taller: the Height of Dutch Children From 1955 to 2009.
Pediatric Research 73, 371–77.
Schreider, E. (1950). Geographical distribution of the
body-weight/body-surface ratio. Nature 165, 286.
Scott, E. C. & Bajema, C. J. (1982). Height, weight and fertility among the
participants of the 3rd Harvard growth study. Human Biology 54, 501–516.
Scrimshaw, N. S. & Young, V. R. (1989). Adaptation to low protein and energy
intakes. Human Organization 48, 20–30.
Sear, R. (2006). Height and reproductive success. Human Nature 17, 405–418.
Sear, R. (2010). Height and reproductive success. In Homo Novus—a Human
without Illusions (eds U. J. Frey, C. Störmer and K. P. Willführ), pp.
127–143. Springer, Berlin, Heidelberg.
Sear, R., Allal, N. & Mace, R. (2004). Height, marriage and reproductive
success in Gambian women. Research in Economic Anthropology 23, 203–224.
Sear, R. & Marlowe, F. W. (2009). How universal are human mate choices? Size
does not matter when Hadza foragers are choosing a mate. Biology Letters 5,
606–609.
Seckler, D. (1982). Small but healthy: a basic hypothesis in the theory,
measurement and policy of malnutrition. In Newer Concepts in Nutrition and
their Implication for Policy. (Sukhatme, P. V., ed.), pp. 127–137. Maharashtra
Association for the Cultivation of Science Research Institute, Pune, India.
Sell, A., Cosmides, L., Tooby, J., Sznycer, D., von Rueden, C. & Gurven, M.
(2009). Human adaptations for the visual assessment of strength and fighting
ability from the body and face. Proceedings of the Royal Society B: Biological Sciences
276, 575–584.
Shami, S. & Tahir, M. (1979). Operation of natural selection on human height.
Pakistan Journal of Zoology 11, 75–83.
Sheiner, E., Sarid, L., Levy, A., Seidman, D. S. & Hallak, M. (2005). Obstetric
risk factors and outcome of pregnancies complicated with early postpartum
hemorrhage: a population-based study. Journal of Maternal-Fetal and Neonatal
Medicine 18, 149–154.
Shepperd, J. A. & Strathman, A. J. (1989). Attractiveness and height the
role of stature in dating preference, frequency of dating, and perceptions of
attractiveness. Personality and Social Psychology Bulletin 15, 617–627.
Shine, R. (1991). Intersexual dietary divergence and the evolution of sexual
dimorphism in snakes. American Naturalist 138, 103–122.
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
30 Gert Stulp and Louise Barrett
Siepielski, A. M., DiBattista, J. D. & Carlson, S. M. (2009). It’s about time:
the temporal dynamics of phenotypic selection in the wild. Ecology Letters 12,
1261–1276.
Silventoinen, K. (2003). Determinants of variation in adult body height. Journal
of Biosocial Science 35, 263–285.
Silventoinen, K., Helle, S., Nisén, J., Martikainen, P. & Kaprio, J. (2013).
Height, age at first birth, and lifetime reproductive success: a prospective
cohort study of Finnish male and female twins. Twin Research and Human
Genetics 16, 581–589.
Silventoinen, K., Kaprio, J. & Lahelma, E. (2000). Genetic and environmental
contributions to the association between body height and educational attainment:
a study of adult Finnish twins. Behavior Genetics 30, 477–485.
Silventoinen, K., Kaprio, J., Lahelma, E., Viken, R. J. & Rose, R. J. (2001). Sex
differences in genetic and environmental factors contributing to body-height.
Twin Research 4, 25–29.
Silventoinen, K., Kaprio, J., Lahelma, E., Viken, R. J. & Rose, R. J. (2003a).
Assortative mating by body height and BMI: Finnish twins and their spouses.
American Journal of Human Biology 15, 620–627.
Silventoinen, K., Lahelma, E. & Rahkonen, O. (1999). Social background,
adult body-height and health. International Journal of Epidemiology 28, 911–918.
Silventoinen, K., Pietiläinen, K. H., Tynelius, P., Sørensen, T. I., Kaprio, J.
& Rasmussen, F. (2008). Genetic regulation of growth from birth to 18 years
of age: the Swedish young male twins study. American Journal of Human Biology
20, 292–298.
Silventoinen, K., Posthuma, D., Van Beijsterveldt, T., Bartels, M. &
Boomsma, D. I. (2006). Genetic contributions to the association between
height and intelligence: evidence from Dutch twin data from childhood to
middle age. Genes, Brain and Behavior 5, 585–595.
Silventoinen, K., Sammalisto, S., Perola, M., Boomsma, D. I., Cornes, B.
K., Davis, C., Dunkel, L., de Lange, M., Harris, J. R., Hjelmborg, J. V. B.,
Luciano, M., Martin, N. G., Mortensen, J., Nisticò, L., Pedersen, N. L.,
et al. (2003b). Heritability of adult body height: a comparative study of twin
cohorts in eight countries. Twin Research: the Official Journal of the International
Society for Twin Studies 6, 399–408.
Simpson, S. W., Quade, J., Levin, N. E., Butler, R., Dupont-Nivet, G.,
Everett, M. & Semaw, S. (2008). A female Homo erectus pelvis from Gona,
Ethiopia. Science 322, 1089–1092.
Sorokowski, P. & Butovskaya, M. L. (2012). Height preferences in humans
may not be universal: evidence from the Datoga people of Tanzania. Body
Image 9, 510–516.
Sorokowski, P., Sorokowska, A. & Danel, D. P. (2013). Why pigs are important
in Papua? Wealth, height and reproductive success among the Yali tribe of
West Papua. Economics & Human Biology 11, 382–390.
Sorokowski, P., Sorokowska, A., Fink, B. & Mberira, M. (2011). Variable preferences
for sexual dimorphism in stature (SDS) might not be universal: data
from a semi nomad population (Himba) in Namibia. Journal of Cross-Cultural
Psychology 43, 32–37.
Sovio, U., Bennett, A. J., Millwood, I. Y., Molitor, J., O’Reilly, P. F.,
Timpson, N. J., Kaakinen, M., Laitinen, J., Haukka, J. & Pillas, D. (2009).
Genetic determinants of height growth assessed longitudinally from infancy
to adulthood in the northern Finland birth cohort 1966. PLoS Genetics 5,
e1000409.
Spencer, N. J. & Logan, S. (2002). The treatment of parental height as a
biological factor in studies of birth weight and childhood growth. Archives of
Disease in Childhood 87, 184–187.
Spuhler, J. N. (1982). Assortative mating: assortative mating with respect to
physical characteristics. Biodemography and Social Biology 29, 53–66.
Stearns, S. (1992). The Evolution of Life Histories. Oxford University Press,
Oxford.
Stearns, S. C. (2000). Life history evolution: successes, limitations, and
prospects. Naturwissenschaften 87, 476–486.
Stearns, S. C., Byars, S. G., Govindaraju, D. R. & Ewbank, D. (2010).
Measuring selection in contemporary human populations. Nature Reviews
Genetics 11, 611–622.
Stearns, S. C., Govindaraju, D. R., Ewbank, D. & Byars, S. G. (2012).
Constraints on the coevolution of contemporary human males and females.
Proceedings of the Royal Society B: Biological Sciences 279, 4836–4844.
Steckel, R. H. (1995). Stature and the standard of living. Journal of Economic
Literature 33, 1903–1940.
Steckel, R. (2002a). A history of the standard of living in the United States.
In EH.Net Encyclopaedia. (ed. R. Whaples), http://eh.net/encyclopedia/
a-history-of-the-standard-of-living-in-the-united-states/ (accessed 24/11/14)
Steckel, R. H. (2002b). Health, nutrition and physical well-being. In Historical
Statistics of the United States: Millenial Edition (eds S. Carter, S. Gartner, M.
Haines, A. Olmstead, R. Sutch and G. Wright), pp. 499–620. Cambridge
University Press, New York.
Steckel, R. H. (2009). Heights and human welfare: recent developments and
new directions. Explorations in Economic History 46, 1–23.
Stulp, G., Buunk, A. P., Kurzban, R. & Verhulst, S. (2013a). The height
of choosiness: mutual mate choice for stature results in suboptimal pair
formation for both sexes. Animal Behaviour 86, 37–46.
Stulp, G., Buunk, A. P. & Pollet, T. V. (2013b). Women want taller men
more than men want shorter women. Personality and Individual Differences 54,
877–883.
Stulp, G., Buunk, A. P., Pollet, T. V., Nettle, D. & Verhulst, S. (2013c). Are
human mating preferences with respect to height reflected in actual pairings?
PLoS ONE 8, e54186.
Stulp, G., Buunk, A. P., Verhulst, S. & Pollet, T. V. (2013d). Tall claims? Sense
and nonsense about the importance of height of US presidents. The Leadership
Quarterly 24, 159–171.
Stulp, G., Buunk, A. P., Verhulst, S. & Pollet, T. V. (2012a). High and mighty:
height increases authority in professional refereeing. Evolutionary Psychology
10, 588–601.
Stulp, G., Kuijper, B., Buunk, A. P., Pollet, T. V. & Verhulst, S. (2012b).
Intralocus sexual conflict over human height. Biology Letters 8, 976–978.
Stulp, G., Pollet, T. V., Verhulst, S. & Buunk, A. P. (2012c). A curvilinear
effect of height on reproductive success in human males. Behavioral Ecology
and Sociobiology 66, 375–384.
Stulp, G., Verhulst, S., Pollet, T. V. & Buunk, A. P. (2012d). The effect of
female height on reproductive success is negative in Western populations, but
more variable in non-western populations. American Journal of Human Biology
24, 486–494.
Stulp, G., Mills, M., Pollet, T. V. & Barrett, L. (2014). Non-linear associations
between stature and mate choice characteristics for American men and
their spouses. American Journal of Human Biology 26, 530–537.
Stulp, G., Verhulst, S., Pollet, T. V., Nettle, D. & Buunk, A. P. (2011).
Parental height differences predict the need for an emergency caesarean
section. PLoS ONE 6, e20497.
Subramanian, S. V. & Ackerson, L. K. (2009). Association of maternal height
with child mortality, anthropometric failure, and anemia in India. JAMA 301,
1691–1701.
Takahashi, E. (1984). Secular trend in milk consumption and growth in Japan.
Human Biology 56, 427–437.
Tanner, J. M. (1962). Growth at Adolescence. Blackwell Scientific Publications,
Oxford.
Tanner, J. M. (1963). The regulation of human growth. Child Development 34,
817–847.
Tanner, J. M. (1981). Growth and maturation during adolescence. Nutrition
Reviews 39, 43–55.
Tanner, J. M. (1990). Foetus into Man: Physical Growth from Conception to Maturity.
Harvard University Press; Cambridge, Mass.
Tanner, J. M., Hayashi, T., Preece, M. A. & Cameron, N. (1982). Increase in
length of leg relative to trunk in Japanese children and adults from 1957 to
1977: comparison with British and with Japanese Americans. Annals of Human
Biology 9, 411–423.
Turchin, M. C., Chiang, C. W. K., Palmer, C. D., Sankararaman, S., Reich,
D., Genetic Investigation of ANthropometric Traits (GIANT) Consortium &
Hirschhorn, J. N. (2012). Evidence of widespread selection on standing
variation in Europe at height-associated SNPs. Nature Genetics 44, 1015–1019.
Vick, A. E. (2005). Sexual Dimorphism and the Transition to Agriculture: A
Meta-analysis. Unpublished Ph.D. Thesis, University of Florida.
Visscher, P. M., Macgregor, S., Benyamin, B., Zhu, G., Gordon, S., Medland,
S., Hill, W. G., Hottenga, J.-J., Willemsen, G. & Boomsma, D. I. (2007).
Genome partitioning of genetic variation for height from 11,214 sibling pairs.
The American Journal of Human Genetics 81, 1104–1110.
Visscher, P. M., Medland, S. E., Ferreira, M. A., Morley, K. I., Zhu, G.,
Cornes, B. K., Montgomery, G. W. & Martin, N. G. (2006). Assumption-free
estimation of heritability from genome-wide identity-by-descent sharing
between full siblings. PLoS Genetics 2, e41.
Walker, R., Gurven, M., Hill, K., Migliano, A., Chagnon, N., De Souza, R.,
Djurovic, G., Hames, R., Hurtado, A. M., Kaplan, H., Kramer, K., Oliver,
W. J., Valeggia, C. & Yamauchi, T. (2006). Growth rates and life histories in
twenty-two small-scale societies. American Journal of Human Biology 18, 295–311.
Walker, R. S. & Hamilton, M. J. (2008). Life-history consequences of density
dependence and the evolution of human body size. Current Anthropology 49,
115–122.
Wells, J. C. K., DeSilva, J. M. & Stock, J. T. (2012). The obstetric dilemma: an
ancient game of Russian roulette, or a variable dilemma sensitive to ecology?
American Journal of Physical Anthropology 149, 40–71.
Widén, E., Ripatti, S., Cousminer, D. L., Surakka, I., Lappalainen, T.,
Järvelin, M.-R., Eriksson, J. G., Raitakari, O., Salomaa, V. & Sovio, U.
(2010). Distinct variants at LIN28B influence growth in height from birth to
adulthood. The American Journal of Human Genetics 86, 773–782.
Winkler, E. M. & Kirchengast, S. (1994). Body dimensions and differential
fertility in Kung San males from Namibia. American Journal of Human Biology
6, 203–213.
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society
Evolution and human height 31
Wittman, A. B. & Wall, L. L. (2007). The evolutionary origins of obstructed
labor: bipedalism, encephalization, and the human obstetric dilemma. Obstetrical
& Gynecological Survey 62, 739–748.
Woitek, U. (2003). Height cycles in the 18th and 19th centuries. Economics and
Human Biology 1, 243–257.
Wolfe, L. D. & Gray, J. P. (1982). Subsistence practices and human sexual
dimorphism of stature. Journal of Human Evolution 11, 575–580.
Wormser, D., Angelantonio, E. D., Kaptoge, S., Wood, A. M., Gao, P., Sun,
Q., Walldius, G., Selmer, R., Verschuren, W. M. & Bueno-de-Mesquita, H.
B. (2012). Adult height and the risk of cause-specific death and vascular morbidity
in 1 million people: individual participant meta-analysis. International
Journal of Epidemiology 41, 1419–1433.
Worthman, C. M. (2003). Energetics, sociality, and human reproduction:
life history theory in real life. In Offspring: Human Fertility Behavior in
Biodemographic Perspective (eds K. W. Wachter and R. A. Bulatao), pp.
289–321. The National Academies Press, Washington.
Yang, J., Benyamin, B., McEvoy, B. P., Gordon, S., Henders, A. K., Nyholt,
D. R., Madden, P. A., Heath, A. C., Martin, N. G. & Montgomery, G. W.
(2010). Common SNPs explain a large proportion of the heritability for
human height. Nature Genetics 42, 565–569.
Yee, N. & Bailenson, J. (2007). The Proteus effect: the effect of transformed
self-representation on behavior. Human Communication Research 33, 271–290.
Young, T. J. & French, L. A. (1996). Height and perceived competence of US
presidents. Perceptual and Motor Skills 82, 1002.
Zhu, H., Shah, S., Shyh-Chang, N., Shinoda, G., Einhorn, W. S.,
Viswanathan, S. R., Takeuchi, A., Grasemann, C., Rinn, J. L. & Lopez,
M. F. (2010). Lin28a transgenic mice manifest size and puberty phenotypes
identified in human genetic association studies. Nature Genetics 42, 626–630.
(Received 3 January 2014; revised 28 October 2014; accepted 11 November 2014 )
Biological Reviews (2014) 000–000 © 2014 Cambridge Philosophical Society