Journal of Marriage and the Family 62 (November 2000): 1018­10341018
ALAN BOOTH, KAREN CARVER, AND DOUGLAS A. GRANGER*
Pennsylvania State University
Biosocial Perspectives on the Family
COURTSHIP AND MATE SELECTION
Among the most fascinating--but also puzzling--
recent findings are those that suggest an associa-
tion between a basic feature of the immune system
and the process of selecting a mate. Immunolo-
gists long ago identified basic features of our cells
that enable the immune system to recognize self
versus other and subsequently eliminate potential-
ly damaging molecules it determines as other. The
basic feature of this part of the immune system is
proteins found on cell surfaces called human leu-
kocyte antigens (HLA) or the major histocompat-
ibility complex (MHC). Put simply, the MHC de-
fines for each person a unique ``immunological
fingerprint.'' Recent findings suggest that inter-
personal cues signal information about individual
differences in MHC. Humans can detect individ-
ual differences in odors (sweat) associated with
MHC, which influence decisions regarding mate
selection and perceived attractiveness (Wedekind,
1028 Journal of Marriage and the Family
Seebeck, Bettens, & Paepke, 1995). In other
words, mate selection might be influenced by ol-
factory or other cues that signal immunological
differences. The greater the immunological differ-
ences, the greater the chances of producing a vi-
able infant. Inbreeding avoidance may be the most
important function of MHC-associated mating
preferences (Potts, Manning, & Wakeland, 1994).
Studies of mice suggest that MHC preferences
come about through imprinting (Yamazaki et al.,
1988). Infants learn how their own MHC type
smells, and evolutionary forces have evolved a
preference for dissimilar types.
It is of interest that scores of studies find be-
havioral and social similarity important to under-
standing mate selection. Winch, Ktsanes, and
Ktsanes's (1954) theory of complementary needs
never received much support (e.g., Udry, 1964).
The MHC studies draw family scholars back to
exploring complementarity, albeit in a different
form, as an explanatory variable.
This preference for immunological differences
would certainly help to explain mate selection
studies of Kibbutz marriages and Chinese ar-
ranged marriages. Shepher (1971) studied mate
selection in Israel Kibbutz where from the time of
birth, children were raised in child-care facilities.
Parents saw them a few hours a day, but most of
the time they were with the care providers and
other children. Shepher observed that, upon reach-
ing adulthood, individuals never married someone
from the same facility. Wolf (1995) studied ar-
ranged marriages in China that took place in the
early part of this century. Marriages were often
arranged when children were very young. In some
communities, the female child would go to live in
the male's home where she was treated as one of
the children. In other communities, the female re-
mained with the birth parents until mature, where-
upon she moved to the male's family. Compared
with those who did not reside together until ma-
turity, the couples who lived together as children
had unsuccessful marriages. Many were never
consummated, and few had children. Men were
consistently unfaithful and had children with mis-
tresses. For MHC preferences to be the explana-
tory mechanism in these studies, we would need
evidence of imprinting (akin to the mouse studies)
to explain the rejection of kibbutz-mates and sons
of foster families.
Family researchers should find this work of in-
terest not only because of its relation to mate pref-
erences and incest avoidance, but also because of
its relation to birth outcomes. For example, HLA
similarity has been associated with repeated spon-
taneous abortions (Thomas, Harger, Wagener, Ra-
bin, & Gill, 1985), and lower birth weight (Ober
et al., 1987).
Students of contraceptive use also will find the
HLA studies of interest. Estradiol reduces wom-
en's ability to discriminate immunological differ-
ences among potential mates. High estradiol may
be found among pregnant women and women on
``the pill.'' A modern contraceptive method may
be resulting in poor mate selection from the stand-
point of producing children who are less likely to
survive. The inability of these women to detect
appropriate mates may affect the stability of court-
ship relationships. Cohabiting pill users have sig-
nificantly higher rates of union dissolution (con-
trolling for a wide assortment of suspected
covariates) than other nonhormonal-based contra-
ceptors (Carver, 1998).
Developments in another line of research bear
watching because of their relevance to mate se-
lection. Faces judged to have above average sym-
metry are regarded as more attractive. Facial sym-
metry may be associated with greater
immunological competence and increased gene
variation, which means that mating with such in-
dividuals would increase the chances of infant sur-
vival (Gangestad & Buss, 1993; Gangestad &
Thornhill, 1998; Grammar & Thornhill, 1994;
Mitton, 1993; Thornhill & Gangestad, 1993).
Preference for masculine facial features has been
observed to vary during the phase of the menstru-
al cycle. When conception is most likely, women
prefer less masculine faces than during the rest of
the menstrual cycle (Penton-Voak et al., 1999).
The masculine faces may signal immunological
competence, whereas the less masculine faces
may indicate paternal interest and investment in
offspring. Gangestad and Simpson (in press) in-
tegrate these findings into a theory that suggests
women vary their reproductive strategy according
to the harshness of the environment. When the
environment is difficult, women place more
weight on indications of genetic fitness than they
do when the environment is less demanding. How
these findings, if borne out by subsequent studies,
would play out in mate selection or extra-pair sex-
ual relationships is deserving of study.
The integration of measures of basic features
of the immune system into mate selection and
courtship research serves to increase understand-
ing of incest avoidance, contraceptive use, and un-
stable courtship relations as they relate to the evo-
lutionary need to produce viable offspring.
1029Biosocial Perspectives on the Family
RELATIONSHIP QUALITY AND STABILITY
Testosterone's links to marrying and divorcing are
considered first, followed by reports of research
on the relationship between marital quality and
testosterone. Genetic influences on divorce are
considered, as is the association between marital
conflict and immunity.
Marital Status
In the preceding section, several biological mech-
anisms were suggested that may define marital re-
lationship quality and stability. Insight is obtained
from evidence that testosterone levels in men drop
after they marry. In a 10-year longitudinal study
of Air Force officers who underwent four physical
exams over that period of time, Mazur and Mich-
alek (1998) were able to compare changes in tes-
tosterone with changes in marital status. Unmar-
ried men's testosterone levels were high, but
following marriage, they decreased. One scenario
is that single men are mostly in the company of
other men, and everyday competition (some of
which may be over women) keeps testosterone
levels elevated (e.g., Booth, Shelly, Mazur, Tharp,
& Kittok, 1989). Once married, exposure to other
men declined, and the need to compete for women
disappeared. Another scenario is that the marriage
itself lowered testosterone--similar to what was
observed after the birth of an infant. Wives expect
men to behave in supportive and nurturing ways,
and lowering testosterone may be crucial to suc-
cessfully enacting the caring spousal and parent
roles. Alternatively, biological messages (e.g.,
pheromones) having to do with sex or reproduc-
tion may cause testosterone to decrease.
Relationship Quality
Even though marriage is accompanied by a drop
in testosterone, hormones may still be related to
marital quality. An analysis of men from a rep-
resentative sample of 4,462 former military serv-
icemen between the ages of 33 and 42 showed
that men with higher testosterone production were
less likely to marry in the first place; once mar-
ried, they were more likely to divorce (Booth &
Dabbs, 1993). The likelihood of never marrying
was 50% higher for men whose testosterone levels
were one standard deviation above the mean com-
pared with those whose testosterone levels were
one standard deviation below the mean. Similarly,
men at the higher level were 43% more likely to
divorce than were those at the lower level. Once
married, men with higher testosterone levels were
31% more likely to leave home because of a trou-
bled relationship with their wife, 38% more likely
to have extra-marital sex, and 13% more likely to
report hitting or throwing things at their spouse.
In addition, high-testosterone men were more like-
ly to report low-quality marital interaction, a find-
ing supported by Julian and McKenry (1989).
These findings were net of other social variables
such as low socioeconomic status or deviant be-
havior in other arenas. It is important to note,
however, that substantial numbers of men with
high testosterone had excellent marriages. The
mechanism that explains this differential marital
success is unknown. There is also the caveat that
cross-sectional studies do not clarify whether con-
flictual marriages raise testosterone.
On the other hand, marriage does play a pro-
tective role with respect to the link between tes-
tosterone and antisocial behavior and depression.
Men with high testosterone levels are at risk of
committing a crime and being depressed. Mar-
riage, along with steady employment, reduces the
likelihood of both (Booth, Johnson, & Granger,
1999; Booth & Osgood, 1993). Because these
studies are based on cross-sectional data, it is not
possible to estimate the causal ordering of the
variables. The work of Mazur and Michalek
(1998) and Gubernick, Worthman, and Stallings
(1991) has suggested that marriage may reduce
the likelihood that high-testosterone men commit
crimes and get depressed. The nature of the mech-
anism is unclear, however.
We know little about hormones and women's
marriages. Having low levels of testosterone may
be important to relationship quality, or quality
may be associated with hormones associated with
reproduction, such as estradiol or oxytocin. Equal-
ly important is dyadic research on marital partners
to see how hormone-behavior links in one indi-
vidual are related to hormone-behavior links in the
spouse.
Genetics and Divorce
Given that divorce rates are so consistent from
society to society (Goode, 1993), it is not surpris-
ing that a number of studies have shown genes to
influence divorce. Estimates of the heritability of
divorce have ranged from .26 (Turkheimer, Lov-
ett, Robinette, & Gottesman, 1992) to .53 (Jockin,
McGue, & Lykken, 1996; McGue & Lykken,
1992). Jockin et al. (1996) hypothesized that per-
1030 Journal of Marriage and the Family
sonality traits play a key role. They demonstrated
that between 30% and 42% of the heritability of
divorce risk comes from genetic factors affecting
personality. This finding is supported by a study
of the association between parent and offspring
divorce indicating that behavior problems mediate
a significant share of the link (Amato, 1996).
Analysis is needed that combines methods used
by family researchers (survival analysis) with be-
havior genetics methods to explain the genetic
mediation of divorce (e.g., Meyer, Eaves, Heath,
& Martin, 1991).
The consequences of divorce for children may
also have genetic origins. In a large-scale study of
divorce, Block, Block, and Gjerde (1986) and
Cherlin and colleagues (1991) both demonstrated
that boys' elevated risk for behavior problems ob-
served after divorce disappeared when behavior
problems many years before divorce were con-
trolled. Although Cherlin, Chase-Lansdale, and
McRae (1998) demonstrated in a later study that
the gap between children from divorced and non-
divorced families widened as children moved into
young adulthood, there remains a significant
amount of unexplained variance. It is possible that
the behavior problems of the boys before and after
divorce are related because of underlying endur-
ing personality characteristics and not because a
high-conflict marital relationship generates the
problems. This is an example of a finding that
could be greatly informed by including a genetic
component in the study.
Marital Conflict, Immunity, and Health
Data from large epidemiological studies suggest
that poor personal relationships are a major risk
factor for morbidity and mortality (House, Landis,
& Umberson, 1988). The search for mechanisms
has revealed substantial evidence regarding the
role of immune function. Kiecolt-Glaser, Glaser,
Cacioppo, and Malarkey (1998) demonstrated that
abrasive marital interactions have important en-
docrine and immunological correlates. In general,
marital separation or divorce, higher marital con-
flict, and lower marital satisfaction are associated
with lower immune function. Such stress-related
immunological changes may be a pathway
through which close personal relationships influ-
ence health (e.g., infectious diseases, cancer,
wound healing).
Testosterone is related to poor union quality
and stability, as are genetic influences. In contrast,
evidence that environmental factors influence hor-
mone levels involves the finding that testosterone
declines when men marry. Marital conflict and in-
stability may compromise the immune system,
which in turn affects health.
Evolutionary Foundations of Cultural Variation:
Evoked Culture and Mate Preferences
Steven W. Gangestad1
, Martie G. Haselton2
, and David M. Buss3
1
Department of Psychology, University of New Mexico, 2
Communication Studies and
Department of Psychology, University of California at Los Angeles, and 3
Department of
Psychology, University of Texas at Austin. E-mail correspondence: sgangest@unm.edu
The authors thank Alita Cousins, Corey Fincher, Melissa Franklin, Shelly Gable, Christine
Garver, Gian Gonzaga, Anne Peplau, Matt Pirritano, Chris Radi, Glenn Scheyd, and the Gable-
Haselton-Peplau relationships lab group for helpful comments on earlier drafts of this paper.
Running Head: EVOLUTIONARY PSYCHOLOGY AND CULTURE
7/11/2005
Evolutionary Psychology and Cultural Variation 2
Abstract
We articulate an evolutionary perspective on cultural variation, centering on the concept of
evoked culture. We then demonstrate how the framework of evoked culture has been used to
predict and explain cultural variation, and report new tests of hypotheses about cultural variation
in mate preferences. These tests demonstrate the predictive power of ecological variables such
as parasite prevalence that are implicated by evolutionary psychological theories. New empirical
tests provided little support for the predictions advanced by competing social role theories (e.g.,
Eagly & Wood, 1999), with some findings running opposite to those predicted by such theories.
We propose that a well articulated evolutionary perspective on cultural variation may be
particularly useful because it can specify how variation in cultural practice itself may emerge.
We conclude that discussions of cultural variation should move beyond false dichotomies of
"social" versus "biological," and suggest that evolutionary psychology provides frameworks that
transcend these dichotomies.
Evolutionary Psychology and Cultural Variation 8
Environmental Contingency in Mating Strategies
The heuristic value of the evolutionary approach is illustrated by work on non-human
species. Behavioral ecologists study how animals adaptively adjust their behavior to their
ecologies. They generally assume that adaptive adjustments are problem-specific and involve a
multiplicity of adaptations (e.g., Krebs & Davies, 1993). Consider, for example, the collared
flycatcher, a bird species on the island of Gotland in the Baltic Sea. Male and female pairs form
socially monogamous unions. Nonetheless, about 15% of eggs are sired by extra-pair males.
When sexually mature, males develop a patch of white feathers on their foreheads, and males
who sport larger patches account for a disproportionate number of the extra-pair fertilizations
(Sheldon & Ellegren, 1999). Behavioral ecologists speculated that these males are selected as
extra-pair mates because forehead patches are sexually selected indicators of good genes. As
predicted by this hypothesis, (1) females whose social mates have relatively small forehead
patches are particularly likely to engage in extra-pair copulations (Sheldon et al., 1999), (2)
females tend to seek extra-pair matings when they are most fertile (Michl et al., 2002); (3)
offspring of males with large forehead patches are in better condition (as measured by standard
Evolutionary Psychology and Cultural Variation 9
body weight assessments) compared to their half-siblings who are sired by the female's social
mate (Sheldon et al., 1997); (4) the offspring of males with large forehead patches tend to be
male, the sex that most benefits from having such a sire (Ellegren et al., 1996), which suggests
that flycatchers adaptively adjust the sex-ratio of offspring depending on their own qualities or
the qualities of their mates. It is implausible that the adaptive adjustments of the mating behavior
of collared flycatchers are due to adaptations that affect all of their other behavior, such as how
they learn and remember food sources or how they engage in other social interactions. Rather,
just as specific skin tissue of humans responds to sunlight by producing melanin, specific mating
behaviors of collared flycatchers appear to have been specially shaped to be conditional on
specific, context-meaningful environmental features. Discovery and understanding of these
conditional responses would have been unlikely if not for explicit evolutionary theory about
sexual selection on these birds.
Humans should also possess a psychology that is sensitive to a large number of
adaptively relevant environmental variables. To illustrate we consider an example analogous in
many ways to the context-specific responses of the collared flycatcher. Recent research has
shown that changes in women's sexual preferences and interests are intricately patterned. Fertile
women particularly prefer the scent of men who evidence a robust developmental history, as
indicated by phenotypic cues such as bodily symmetry (Gangestad & Thornhill, 1998; Rikowski
& Grammer, 1999; Thornhill & Gangestad, 1999b; Thornhill, Gangestad, Miller, Scheyd,
McCollough, & Franklin, 2003), more masculine faces (Johnston et al., 2001; Penton-Voak et
al., 1999, Penton-Voak & Perrett, 2000), and male behavioral displays of social presence and
intrasexual competitiveness (Gangestad, Simpson, Cousins, Garver, & Christensen, 2004). These
shifts appear to be specific to when women evaluate men as short-term sex partners, not long-
Evolutionary Psychology and Cultural Variation 10
term mates (Gangestad et al., 2004; Haselton & Miller, in press; Penton-Voak et al., 1999). Yet
not all desired traits are more preferred near ovulation. For instance, traits particularly valuable
in long-term mates, such as resources, do not show ovulatory increases in female preference
(Gangestad, 2004; Haselton & Miller, in press; see also Thornhill et al., 2003). The only
explanation as yet proposed to account for these changes is that selection has shaped female
preferences for indicators of genetic benefits to offspring in short-term mates to be enhanced
mid-cycle--the time when women could have benefited by mating with such partners. Indeed,
women appear to show particular sexual interest in men other than primary social partners when
they are fertile (Bellis & Baker, 1990; Gangestad, Thornhill, & Garver, 2002; Haselton &
Gangestad, 2005; but see also Pillsworth, Haselton & Buss, 2004). And, emerging evidence
suggests that women with partners lower on hypothesized fitness indicators are those whose
preferences for extra-pair partners are particularly likely to increase as ovulation approaches
(Haselton & Gangestad, 2005; Gangestad, Thornhill, & Garver-Apgar, in press).
This same line of research has demonstrated a variety of additional context-specific
conditional responses: (1) Women's primary male partners respond contingently based on
correlates of their fertility status; men appear to be more vigilant of the whereabouts of partners
who are in fertile phases than those same partners in non-fertile phases (Gangestad et al., 2002;
Haselton & Gangestad, 2005); (2) Women who see themselves as physically attractive
particularly prefer masculine faces, presumably because they face smaller trade-offs between
qualities advertised by facial masculinity and the effort a partner invests in the relationship, and
hence are more able to command both (Little, Burt, Penton-Voak, & Perrett, 2001); (3) When
women particularly value investment in a relationship from a man, they may prefer less
masculine faces (Penton-Voak, 2001); (4) when women pursue a short-term mating strategy,
Evolutionary Psychology and Cultural Variation 11
they show an elevated preferences for men who are physically attractive and sexy (Buss &
Schmitt, 1993; Greiling & Buss, 2000). In sum, the available evidence points to an intricately-
designed, environmentally-sensitive psychological architecture.
Women's sexual interests are dependent on external factors, such as relationship context
(short-term vs. long-term) and partner quality, as well an important internal cue, her cyclical
fertility status. Considered as a whole, the patterning of women's sexual interests and
preferences cannot be understood as a set of contingent responses that have been shaped by
broad, domain-general learning processes. Rather, the contingent nature of these interests is best
explained by invoking the concept of evolved psychological architecture containing design
features dedicated to solving specific adaptive problems in the domain of mating.
This area of research provides an example in which variable contemporaneous inputs
produce changes in psychological and behavioral outputs. Evolutionary psychologists also
expect responses to environmental factors that may developmentally calibrate or condition
psychological adaptations, producing more stable differences between individuals occupying
different ecologies (Buss, 1991; Tooby & Cosmides, 1990). In short, this conceptual framework
points to the possibility of specialized, problem-specific adaptations underlying patterns of
within-group similarity and between-group difference--what scientists often refer to as culture.
Evoked and Transmitted Culture
Culture can be conceptualized as sets of practices, beliefs, ideas, values, inventions,
artifacts, and attitudes that characterize groups of people. There are at least two pathways
through which cultural variation may emerge: transmission and evocation.
First, the elements of culture may be acquired through modeling or social learning and
transmitted throughout a population. This is, of course, the dominant view in the social sciences,
Evolutionary Psychology and Cultural Variation 12
and is likely one major source of cultural variation. For example, the development and retention
of cumulative knowledge in the form of technology (e.g., canoe-making, agricultural practices,
systems of mathematics.) is probably best explained by cultural transmission (see, e.g., Boyd &
Richerson, 1985, Henrich & Gil-White, 2000; see also Flinn, 1997).
Second, some variation across cultures may be understood in terms of differences in the
social and ecological conditions within which groups live and the specially designed adaptations
humans have for responding to them. Tooby and Cosmides (1992) introduced the term "evoked
culture" to refer to the fact that these conditions (e.g., war, drought, abundance) provide inputs
for a richly responsive domain-specific psychology, and thereby "evoke" different behavioral
repertoires, forging different elements of "culture." The specific content and organization of
culture, then, is partly a product of domain-specific phenotypic sensitivities to environmental
input in conjunction with specific input. Metaphorically, evoked cultural variation can be
understood in terms of a specially programmed jukebox (Tooby & Cosmides, 1992). The
jukebox is designed to play a different song depending on environmental inputs (e.g.,
temperature, population density). As the jukebox is moved from one environment to another (or
as environments change temporally), the jukebox plays different tunes. The variable tunes played
under specific conditions are due to the jukebox's design in concert with specific environmental
inputs (see also Kenrick, Li, & Butner, 2003). To propose that this process accounts for some
important forms of cultural variation is not to deny that human learning occurs, but rather to shift
the emphasis toward understanding how selection has shaped domain-specific phenotypic
sensitivities to environmental inputs.
The preceding discussion of specialized contingent responses points to one set of paths
by which culture may be evoked. In socio-ecological circumstances in which women should
Evolutionary Psychology and Cultural Variation 13
particularly value male relationship investment, they may prefer less masculine faces; where
investment is not especially valued, or where women anticipate only short-term mating, women's
preferences may shift to more masculine faces and other characteristics indicative of good genes
(Penton-Voak, 2001).
How Cultural Variability May Reflect Evoked Culture
In this section, we discuss in greater detail two examples of how evolutionary scientists
have predicted and explained cultural variation in terms of specialized adaptations through which
particular circumstances evoke different practices and preferences. (For additional examples see
Alexander, Hoogland, Howard, Noonan, & Sherman, 1979, Gaulin & Boster, 1992; Holden &
Mace, 1999; Mace & Holden, 1999; Schmitt, in press.)
Mate Preferences and Women's Contribution to Direct Production
Calorie production by men and women. Kaplan, Hill, Lancaster, and Hurtado (2000)
have argued that a significant aspect of hominid evolution giving rise to long life spans,
prolonged investment in juveniles, and large brain size is that, compared to our nearest relatives,
humans consume high-quality but difficult to extract resources such as animal protein. Whereas
chimpanzees obtain about 95% of their calories from collected foods requiring no extraction
(e.g., fruits, leaves), only about 8% of calories consumed by modern hunter-gatherers are from
foods requiring no extraction. Both men and women contribute substantially to their own
subsistence. In the majority of hunter-gatherer populations studied to date, however, the average
adult male generates more calories than he consumes--mostly through hunting. These food
resources yield benefits for reproductive women and juveniles by providing extra calories and
macronutrients such as protein. Marlowe (2001) estimated that, on average, men produced 64%
of the calories in all 95 foraging societies on which sufficient information is available. In Kaplan
Evolutionary Psychology and Cultural Variation 14
et al.'s (2000) analysis of studies that carefully measured produced foods in 9 hunter-gatherer
societies, men generated on average about 66%.1
No such surplus of calories is generated by
male chimpanzees. Women in traditional societies can and do turn the surplus of calories
generated by men into production of offspring and thereby reproductively benefit from this
surplus generated through male hunting (Marlowe, 2001).
Variation in benefits to women through male caloric subsidies. Although women's work
is clearly important to child outcomes (e.g., Hawkes et al., 2001), in traditional cultures women's
direct production of nutritional resources may interfere with their reproduction by increasing the
interval between births and thereby reducing offspring number (e.g., Schlegel & Barry, 1986; see
also Kaplan et al., 2000). Hence, across foraging societies, greater male contribution to diet is
associated with greater female reproductive success (Marlowe, 2001). Men may also benefit
from mating with efficient, industrious mates, but not necessarily ones who invest considerable
effort into access to resources or status competition. Thus, as Buss (1989) predicted and found,
modern women across a range of diverse cultures do appear to place greater emphasis on a
1
Broader samples of cultures (such as the widely used 186 culture Standard Cross-Cultural Sample [SCSS]) include
societies with more developed forms of agriculture, which may less relevant to an understanding of human societies
prior to the last 10,000 years. Nonetheless, estimates based them are similar: 65% in the SCCS (Schlegel & Barry,
1986); 65% in a broader sample of 499 societies (Sanday, 1973). Wood and Eagly (2002) cite Aronoff and Crano's
(1975) mean estimate of 44% of female contribution to subsistence (56% male contribution), based on 862 societies.
As was noted in a response by Carroll (1976), this estimate deviates from others, for reasons that an exchange was
unable to fully resolve. We noticed that Table 3 of Aronoff and Crano (1975), which reports a grouped relative
frequency distribution of female contribution to subsistence across all 862 societies, implies a possible range of 33-
42% for the mean, with a best guess of 38%-close to other mean estimates. Thus, their calculation appears not to
have been the average of all societies' female contributions to subsistence, which probably explains the deviation of
their figure from others.
The implications of this surplus for an understanding of human mating and parenting is a matter of debate.
Hawkes and colleagues (e.g., Hawkes, 1991; Hawkes, O'Connell, & Blurton Jones, 1991; 2001) have argued that
men in hunter-gatherer groups (e.g., the Hadza and Ache) have little opportunity to direct resources to their own
mates and kin and, hence, their hunting has not evolved as a means of directly providing nutritional benefits to mates
and offspring. Kaplan et al. (2000) argue that these male activities have been shaped by selection to partly function
as parenting effort. As Hawkes et al. (2001) acknowledge, the wives and children of good hunters in the Hadza are
better nourished and, hence, even if male hunting has not evolved for family provisioning, the average ancestral
woman could have materially benefited from choosing a male with better access to resources (e.g., through men's
enhanced status among men and thereby their ability to protect mates). Indeed, they note that Hadza women prefer
to marry good hunters.
Evolutionary Psychology and Cultural Variation 15
mate's access to resources than men do (see also Buss, Shackelford, Kirkpatrick, & Larsen,
2001; Kenrick & Keefe, 1992; Sprecher, Sullivan & Hatfield, 1994; Wiederman, 1993).
In foraging populations, however, the degree to which women and juveniles benefit from
male hunting varies. Indeed, in many groups that particularly rely on gathered (as opposed to
hunted) foods, women generate more calories than do men (Kaplan et al., 2000; Marlowe, 2001;
Sanday, 1973; Schlegel & Barry, 1986). The variation partly depends on ecological factors (e.g.,
Marlowe, 2001; Wood & Eagly, 2002). Women can generate dietary resources at a greater rate in
some environments than in others (even while caring directly for offspring, e.g., through
gathering, horticulture, fishing, or hunting of small animals). In these circumstances ancestrally,
the value of men's contribution to producing nutritional resources may have been less, and men
may have been selected to shift effort to activities other than hunting and foraging (e.g.,
alternative activities to compete against men and gain access to mates). Women may still have
benefited from choosing men with the ability to produce resources, but these advantages were
probably smaller when the diet did not consist of large shares of meat.
Due to varying relative benefits from mate preferences for specific attributes such as
access to resources, men and women may have been selected to vary the emphasis they placed
on particular mate preferences as a function of the ecological factors associated with the degree
of female participation in food production. When men generate a smaller surplus in calories,
women may place less emphasis on male resource acquisition abilities. Hence, the sex difference
in preference for a mate with high access to resources may be muted in circumstances in which
women participate more heavily in direct production (see also Schmitt, in press).
When women are not involved in direct food production, their work may focus more on
domestic tasks such as food preparation. One might also expect, then, that when women do not
Evolutionary Psychology and Cultural Variation 16
contribute as much to subsistence, they place fewer demands on a mate to help in these other
domains. By contrast, in conditions in which men contribute fewer nutritional benefits to women
and offspring, an evoked culture perspective might predict that women choose men on the basis
of desirable characteristics other than ability to provision (e.g., status advantages that provide
direct benefits mediated through a social network, genetic benefits to offspring; e.g., Gangestad
& Simpson, 2000; Low, 1990b). As a result, one should expect effective polygyny (variance in
men's sexual access to women) to increase. Moreover, when women depend less on male
contributions, they may be more willing to engage in extramarital relations or, relatedly, be less
concerned about exhibiting restrictive sexual attitudes to their mates (e.g., Gangestad &
Simpson, 2000; Schmitt, in press). In summary, we might expect that, as a function of women's
contribution to subsistence (dictated, at least partly, by ecological factors), a variety of other
features, including mate preferences and sexual attitudes, also change as a result of richly
responsive, domain-specific psychology sensitive to these variations.
Indeed, the anthropological literature on traditional societies reveals a number of
associations between women's contribution to subsistence and variations in mating and
sexuality. High levels of female contribution to subsistence are associated with greater degrees of
polygyny (e.g., Schlegel & Barry, 1986). And, although Schlegel and Barry (1986) did not find
that levels of extramarital mating in the Standard Cross-Cultural Sample database were
significantly associated with female contribution to subsistence in the overall sample, they did
find an association with more permissive attitudes toward premarital sex. Detailed studies of a
number of these cultures point to high levels of female infidelity (particularly in Oceania, e.g.,
the Tiwi, Trukese, Trobrianders; Flinn, 1981). These associations are consistent with the idea
that aspects of culture are evoked by women's relative contribution to subsistence.
Evolutionary Psychology and Cultural Variation 17
Based on this same reasoning, Low (1989) predicted relationships between indices of
women's control of resources and child-rearing practices in the Standard Cross-Cultural Sample.
She found that girls' achievement and aggression were more encouraged and obedience less
encouraged as female control of resources increased.
Social Role Theory and variation in women's preference for resources across cultures.
Low's analysis is also consistent with Eagly and Wood's recent findings that the sex difference
in mate preferences for resource control varies with women's relative empowerment (Eagly &
Wood, 1999; also see Kasser & Sharma, 1999). The United Nations publishes two indices used
by Eagly and Wood (1999) as measures of gender equality: The Gender Empowerment Measure
(GEM), a measure of women's access to positions of power (legislative and managerial
positions), representation in professional/technical occupations, and women's income relative to
men's; and the Gender Development Index (GDI), a complex measure of the relative education,
literacy, life expectancy, and income of the sexes.2
The GEM correlated with the size of the sex
difference in preference for a mate with prospects for financial success, where the mate
preference was assessed by both a rating measure (r = -.29) and a ranking measure (r = -.43).
The associations between the GDI and these measures were weaker but in the same direction (-
.23 and -.33). The GEM and GDI also predicted the sex difference in mate preferences for
domestic skill and age.
Eagly and Wood (1999; also see Buss & Barnes, 1986) explained these findings largely
in terms of social roles. In a subsequent paper, Wood and Eagly (2002) specifically proposed
that male and female divisions of labor are influenced by evolved bodily differences including
the reproductive role of women. They propose that these bodily differences, and not sexual
Evolutionary Psychology and Cultural Variation 18
selection acting directly on men's and women's psychologies, largely explains variation across
cultures in male and female preferences, as well as any pancultural sex differences (Wood &
Eagly, 2002, p. 702). That is, the utilities that men and women perceive are based in part on sex-
typed physical attributes in conjunction with local settings; these produce differing social roles
for men and women through learning. This learning presumably does not involve sex-
differentiated learning processes, but rather sex-differentiated inputs (Wood & Eagly, 2002, p.
702; see also Eagly & Wood, 1999, pp. 412-413). Analogously, tall and short people may learn
different repertoires not because they have different psychological adaptations for learning, but
rather because they experience different environments.
Although Low's hypothesis and Wood and Eagly's biosocial account each propose that
environmental factors adjust mating practices, their explanations for how this adjustment occurs
are divergent, and therefore their proposals should be treated as competing hypotheses that may
explain the associations Eagly and Wood (1999) documented. Wood and Eagly's account
suggests that different cultural practices will be evoked by different ecologies: Means of
economic production affect sexual division of labor, which thereby affect cultural practices.
Low's hypothesis is that humans possess domain-specific adaptations that adjust mating
behaviors depending on environmental cues linked with differential fitness payoffs in ancestral
environments.
We now turn to a second example of how the concept of evoked culture leads to
predictions about cultural variability.
2
One difference between these indices is that numerical values in the GDI are lower when societies diverge in either
direction from gender equality--though, because all variables except life expectancy are always greater for men
than women, the measure largely taps the extent to which female outcomes match those of men.
Evolutionary Psychology and Cultural Variation 19
Mate Preferences and Parasite Prevalence
Parasite threat. Pathogens pose threats to the health of any long-lived organism. While
hosts should evolve defenses against pathogens, no solution to the threat of pathogens is final
because pathogens themselves evolve to overcome host defenses. It is no surprise, then, that
pathogens are major killers of humans, particularly early in the life course. This was almost
certainly true in ancestral human groups. In extant hunter-gatherer groups, about 30-50% of the
population dies before reaching reproductive age, most from disease (e.g., Hill & Hurtado,
1996).
In humans, as well as nearly any host of pathogens, we should expect the evolution of
mate preferences designed to discriminate among potential mates on the basis of health. Healthy
mates are less likely to pass on pathogens to the mate chooser and are more likely to survive to
invest in offspring--investment that is critical to the survival of offspring in human hunter-
gather groups (e.g., in the Ache, Hill & Hurtado, 1996). Furthermore, the fact that hosts must
continually evolve to remain adapted to pathogens that perpetually evolve themselves has as a
consequence that hosts will, at any point in time, differ in their ability to resist pathogens,
particularly macroparasites (e.g., Hamilton, 1980). Thus, choosing a mate who is healthy may
result in more disease-resistant offspring (Hamilton & Zuk, 1982).
Overt signs of poor health (open sores, oozing pustules, lesions, emaciation, yellow eyes,
etc.) should be generally disfavored by members of both sexes. There are also subtle signs of
health and overall condition. Symons (1979) argued that "physical attractiveness" partly reflects
an evolved favorable response to features that function as "health certificates," characteristics
associated with healthy condition (see Sugiyama, 2005, for a comprehensive review of the
Evolutionary Psychology and Cultural Variation 20
evidence). These characteristics may include those promising a capacity to resist pathogens and
hence pathogen-resistant genes giving advantages to offspring.3
Parasites and polygyny. Low (1990a) argued that humans living in areas with higher
levels of parasites should have higher levels of polygyny. Her argument was that parasites
compromise the investment capabilities of some portion of men, rendering fewer men viable
mates. As a result, women will more often cross a "polygyny threshold"the point at which
becoming a second mate of a male is more desirable than becoming the first mate of the most
attractive available unmated male (Orians, 1969). In the Standard Cross-Cultural Sample, her
prediction was confirmed; an index of parasite prevalence (including Leishmania, Trypanosoma,
malaria, Schistosoma, filaria, spirochetes, and leprosy) predicted the degree of polygyny across
cultures.
Parasites and physical attractiveness. In a subsequent study, Gangestad and Buss (1993)
asked whether mate preferences shift when individuals occupy ecologies with high levels of
parasites. In such circumstances, we might expect individuals to place greater weight on physical
attractiveness as a certificate of current health or an indicator of pathogen-resistant genes.
Additional analyses of the cross-cultural data from Buss (1989) revealed that, indeed, parasite
prevalence is positively correlated with importance of physical attractiveness as a mate
preference for both sexes, using culture as the unit of analysis. Gangestad and Buss interpreted
these differences as reflecting differences in evoked culture--the cultural patterns were due to
3
Rhodes, Zebrowitz, Clark, Kalick, Hightower, & McKay (2001) examined the association between components of
physical attractiveness (averageness and symmetry) and actual health records and found few relationships. As noted
by Thornhill and Gangestad (1999a), however, "good condition" is a more general concept in evolutionary biology
than in everyday usage. The individual in good condition has an ability to take in and effectively "allocate"
nutritional resources to fitness-enhancing activities. Two individuals of equal "health" may still differ in condition.
In fact, under some circumstances individuals in better condition may be more susceptible to pathogens (e.g., when
their optimal strategy for allocating energy leads them to actually weaken immune function in favor of alternative
fitness-enhancing activities; see Getty, 2002; Kokko, 2001). That this is so should not obscure the fact that their
condition gives them reproductive advantages over others.
Evolutionary Psychology and Cultural Variation 21
responses of an evolved, specially designed mating psychology to ecological factors that
moderate the association between certain characteristics (in this case, physical attractiveness) and
mate value.
New predictions derived from the parasite hypothesis. Additional predictions can be
derived from the preceding logic of the parasite hypothesis. In addition to physical attractiveness,
a number of other characteristics from the 37 cultures study may be associated with mate value.
These predictions are as follows:
1) Current health. Signs of current health may indicate low current parasite load and high
parasite resistance; hence health should be preferred more in parasite-prevalent environments.
2) Good heredity and robustness. Likewise, signs of physical robustness or a family
history thereof may indicate low current load and high resistance; hence they should be preferred
more in parasite-prevalent environments.
3) Intelligence and intrasexual competitive abilities. Low (1990a) argued that sexual
selection increases in pathogen-prevalent environments; male reproductive success in particular
should vary more in such environments. Increases in sexual selection may increase male attempts
to display good condition through successful intrasexual competition. Work using fluctuating
asymmetry as a marker of developmental health (asymmetry due to imprecision of development
due to perturbations caused by disease, mutations, and toxins) has shown that male social
dominance and intelligence are associated with good developmental health (see Gangestad &
Thornhill, 1997). In parasite-prevalent environments, intellectual abilities may be compromised
by parasites (e.g., Watkins & Pollitt, 1997) and, hence, male intelligence and intrasexual
competitive abilities may be particularly valued in pathogen-prevalent environments (see Miller,
Evolutionary Psychology and Cultural Variation 22
2000, for additional arguments for the importance of intelligence as an indicator of pathogen-
resistance).
4) Paternal investment. Mate selection often, if not always, requires tradeoffs. If men are
valued for their health because it signals heritable ability to resist pathogens (e.g., as revealed
through intrasexual competitive abilities and intelligence), women may compromise their desire
to have a mate who is highly investing in offspring for access to a higher value mate (Gangestad
& Simpson, 2000). (This prediction need not follow if women prefer health because it signals
greater ability to invest in offspring.) Life history theory indicates that, as adult mortality rates
increase, the payoffs to high investment in offspring decrease. High levels of paternal
investment, therefore, provide fewer benefits when parasites increase the extrinsic mortality rate
(Robson & Kaplan, 2003).
In the cases of both women's access to resources and pathogen prevalence, differences
across cultures may reflect differences in evoked culture--in these particular instances, patterns
of mate preferences sensitive to cues of which features are especially important to mate value.
These patterns reflect special design for adaptively modifying mate preferences based on
ancestral fitness utility of cues such as parasite prevalence. It should be noted that, because the
two sets of predictions are based on different evolutionary hypotheses, they are logically
independent. That is, one evoked culture hypothesis could be correct (e.g., pathogen prevalence),
even if the other one is not (e.g, women's access to resources; see Buss, 1995).