ORIGINS OF SEX DIFFERENCES IN HUMAN BEHAVIOR
The Origins of Sex Differences in Human Behavior:
Evolved Dispositions Versus Social Roles
Alice H. Eagly and Wendy Wood
Northwestern University Texas A&M University
Manuscript submitted for publication; not for citation
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The ultimate causes of sex differences in human behavior can lie mainly in
evolved dispositions that differ by sex or mainly in the differing
placement of women and men in the social structure. The present article
contrasts these evolutionary and social structural origin theories of sex
differences and illustrates the explanatory power of each theory to account
for sex differences in mate selection preferences, a research area that
often has been interpreted as providing support for evolutionary
perspectives. A reanalysis of Buss's (1989a) 37 cultures study of sex
differences in attributes valued in potential mates provided strong support
for the social structural account of cross-cultural variation in sex
differences in mate preferences.
The Origins of Sex Differences in Human Behavior:
Evolved Dispositions Versus Division of Labor
As more research psychologists have become willing to acknowledge that some
aspects of social behavior, personality, and abilities differ between women
and men (e.g., Eagly, 1995; Halpern, 1997), their attention has begun to
focus on the causes of these differences. Debates about causes center at
least in part on determining what can be considered the basic or ultimate
cause of sex differences. Theories of sex differences that deal with causes
at this level are termed in this article origin theories (Archer, 1996). In
such theories, causation flows from a basic cause to sex-differentiated
behavior, and biological, psychological, and social processes mediate the
relation between the basic cause and behavior. In this article, we consider
two types of origin theories: One of these implicates evolved psychological
dispositions, and the other implicates social structure. Evolutionary
psychology, as illustrated in the work of Buss (1995a), Kenrick and Keefe
(1992), and Tooby and Cosmides (1992), thus represents the first type of
origin theory, and social psychological theories that emphasize social
structure represent the second of type of origin theory (e.g., Berger,
Wagner, & Zelditch, 1985; Eagly, 1987; Eagly & Wood, 1991; House, 1981;
Lorenzi-Cioldi, in press; Ridgeway, 1991; Ridgeway & Walker, 1995; West &
Zimmerman, 1987; Wiley, 1995).
In the evolutionary origin theory, the critical causal arrow points from
evolutionary adaptations to psychological sex differences. Because women
and men possess sex-specific evolved mechanisms, they differ
psychologically and tend to occupy different social roles. In contrast, in
the social structural origin theory, this critical causal arrow points from
social structure to psychological sex differences. Because of the division
of labor, women and men become psychologically different in ways that
adjust them to their respective social roles.
One important feature is shared by these two origin theories: Both offer a
functional analysis of behavior that emphasizes adjustment to environmental
conditions. However, the two schools of thought differ radically in their
analysis of the nature and timing of the adjustments that are most
important to sex-differentiated behavior. Evolutionary psychologists
believe that females and males faced different pressures in primeval
environments when the human species evolved and that the sexes' differing
status with respect to reproduction was the key feature of ancestral life
that framed sex-typed adaptive problems. The resolutions of these problems
produced sex-specific evolved mechanisms that humans carry with them as a
species and that are held to be the root cause of sex-differentiated
behavior. Although many evolutionary psychologists readily acknowledge the
abstract principle that environmental conditions can influence the
development and expression of evolved dispositions in individual lives,
variation of sex differences in response to individual, situational, or
cultural conditions is rarely investigated systematically (e.g., Archer,
1996; Buss, 1995b; Buss & Kenrick, 1998). For example, Buss (1998, p. 421)
emphasized "universal or near-universal sex differences" in preferences for
long-term mates, although he acknowledged some bases for cultural variation
in certain aspects of mating strategies.
Social structuralists maintain that the particular situations faced by
women and men are quite variable across societies and historical periods as
social organization changes in response to technological, ecological, and
other transformations. From a social structural perspective, a society's
division of labor between the sexes is the engine of sex-differentiated
behavior, because it summarizes the social constraints under which men and
women carry out their lives. Sex differences are viewed as accommodations
to the differing restrictions and opportunities that a society maintains
for its men and women, and sex-differentiated behavior is held to be highly
contingent on a range of individual, situational, and cultural conditions
(see Deaux & LaFrance, 1998). Despite this emphasis on the social
environment, social structuralists typically acknowledge the importance of
some biological sex differences. As Eagly (1987) argued, physical
differences between the sexes, such as men's greater size and strength and
women's childbearing and lactation, are very important because they
interact with shared cultural beliefs, social organization, and the demands
of the economy to influence the role assignments that constitute the sexual
division of labor within a society (Wood & Eagly, 1998).
These thumbnail sketches of these two origin theories should make clear
that this debate about the ultimate cause of sex differences cannot be
reduced to a simple nature versus nurture dichotomy. Both evolutionary
theory and social structural theory are interactionist in the sense that
they take biological and environmental factors into account, but they treat
these factors quite differently. Evolutionary theory views sex-specific
evolved dispositions as psychological tendencies that were built in through
genetically mediated adaptation to primeval conditions; the theory treats
contemporary environmental factors as cues that interact with adaptations
to yield sex-typed responses. Social structural theory views
sex-differentiated tendencies as built in through learning-mediated
accommodation to the contemporaneous sexual division of labor; in this
approach, physical differences between the sexes can serve as important
constraints on role assignment.
Another caution is that these theories do not merely reflect different
levels of analysis. Some attempts to reconcile the two perspectives have
proposed that social structural theories identify proximal, contemporaneous
causes for the behavior of women and men, whereas evolutionary analyses
invoke more distal causes that arose early in human history (e.g.,
Borkenau, 1992; Jackson, 1992; Schaller, 1997). Although the timing of the
human adjustment to environmental conditions that is deemed critical is
indeed different in the two theories, they propose causes that are similar
in their position on the proximal versus distal continuum of causality.
Both theories thus propose psychological causes (i.e., evolved
dispositions, role expectations) that operate in the present and whose
impact on behavior is in turn mediated by a range of more proximal
psychological processes (e.g., attitudes and beliefs). The social
structural perspective is thus in stark contrast to evolutionary psychology
models that attribute sex differences in contemporary society to sex-typed
evolved mechanisms (e.g., Buss, 1995a; Tooby & Cosmides, 1992). The causes
of sex differences in evolutionary psychology involve these mechanisms,
which are intended to replace the social psychological mechanisms featured
in theories that give a key role to social structure.
It also would be inappropriate to conclude that social structural theory is
incompatible in general with an evolutionary approach. The evolutionary
perspective is broad and encompasses many specific theories in addition to
the models featured in contemporary evolutionary psychology in the writings
of Buss (Buss, 1995a, 1996; Buss & Kenrick, 1998) and other scholars (e.g.,
Daly & Wilson, 1998; Tooby & Cosmides, 1992). Social structural analyses
suggest an evolved organism, but one in which evolutionary pressures
yielded broad dispositions such as the capacity for group living or for
culture. These analyses do not imply that people's minds are blank slates,
because humans possess facilities, such as for language, that develop in
certain ways, given appropriate environments.
To illustrate the contrasting approaches of these two theories, we will
first present and discuss each theory. Then we will examine their
predictions concerning the criteria men and women use in selecting mates.
This domain of behavior has been central to evolutionary theorizing about
human sex differences (e.g., Buss & Schmitt, 1993; Kenrick & Keefe, 1992),
and the cross-cultural findings available in this area provide an excellent
opportunity to examine empirically some of the divergent predictions of
evolutionary and social structural analyses.
Evolutionary Psychology as an Origin Theory of Sex Differences
From an evolutionary perspective, human sex differences reflect adaptations
to the pressures of the differing physical and social environments that
impinged on women and men during primeval times when the human species
emerged in its anatomically modern form (Buss, 1995a; Tooby & Cosmides,
1992). Evolutionary psychologists thus label those environments that
produced a species' evolved tendencies as its environment of evolutionary
adaptedness, abbreviated as the EEA (Cosmides, Tooby, & Barkow, 1992;
Symons, 1979, 1992; Tooby & Cosmides, 1990b). They loosely identify the
Pleistocene era as the human EEA and generally assume that these
environments were populated by hunter-gatherer groups. To the extent that
ancestral women and men faced different adaptive problems in the EEA, the
two sexes developed different strategies to ensure their survival and
maximize their reproductive success. The resolutions to sex-linked survival
and reproductive problems produced evolved psychological mechanisms that
are specific to each problem domain and that differ between women and men.
Humans then carry these sex-differentiated mechanisms with them as a
species, along with the mechanisms shared by the two sexes.
Although the evolved mechanisms that characterize humans developed in
response to the types of problems consistently encountered by humans'
ancestors and thus are universal attributes of humans, environmental input
affects how these mechanisms develop in individuals and how they are
expressed in behavior (e.g., Buss & Kenrick, 1998). Because culture
influences developmental experiences and patterns current situational
input, culture is in principle important to the expression of adaptive
mechanisms (Tooby & Cosmides, 1992). However, evolutionary psychologists
have devoted relatively little attention to the interaction between such
environmental contexts and the evolved mechanisms that underlie sex
differences. The contextual factors they have considered generally relate
very narrowly to their hypothesized mechanisms-for example, Buss (1991)
maintained that, in order for women to exercise their evolved preference
for men who offer resources, men who vary in resources must be present.
Because of this relative neglect of context, evolutionary psychologists
have generated little understanding of how variation in sex-differentiated
behavior arises from developmental factors and features of social structure
and culture (for exceptions, see Draper & Harpending, 1982; Gangestad &
Simpson, 1997). In practice, most evolutionary psychologists emphasize what
they believe is the relative uniformity of human sex differences across
individual and cultural variables (e.g., Archer, 1996; Buss, 1995b; Buss &
Kenrick, 1998; A. Campbell, in press), despite their frequent
acknowledgment that it is the interplay between evolved dispositions and
current environmental influences that produces behavior (e.g., Buss, 1996;
Tooby & Cosmides, 1990b). Evolutionary psychologists thus typically
emphasize "deeply rooted and universal human behavioral and cognitive
traits" (Foley, 1996, p. 195).
The aspect of evolutionary theory that has been applied most extensively to
sex differences is the theory of sexual selection initially proposed by
Darwin (1871) and further developed by Trivers (1972). In this view,
sex-typed features evolved through male competition, by which the
attributes of certain males fostered successful competition in dominance
contests with other males and thereby conferred a reproductive advantage on
these dominant males. Sex-typed features also evolved through females'
choice of mates, by which females selectively chose to mate with males who
displayed certain desirable attributes and thereby conferred a reproductive
advantage on these desirable males.
Because women constituted the sex that devoted greater effort to parental
investment, they were a limited reproductive resource for men, the less
investing sex (e.g., Buss, 1996). Differential investment occurred because
gestating, bearing, and nursing children restricted the number of children
that women could propagate during their lifespan, whereas men did not have
these restrictions. Men therefore competed for access to women, and women
chose mates from among the available men. As the more investing sex, women
were selected for their wisdom in choosing mates who could provide
resources or protection. Women's preferences for such men, in turn,
produced sexual selection pressures on men to satisfy these criteria.
According to popular theories of sexual selection in humans, sex
differences in parental investment established different rules for
reproductive success for men and women and consequently different adaptive
strategies (Buss, 1996; Kenrick, Trost, & Sheets, 1996). It was to men's
advantage in terms of fitness outcomes to "devote a larger proportion of
their total mating effort to short-term mating than do women" (Buss &
Schmidt, 1993, p. 205)-that is, to be relatively promiscuous. Women, in
contrast, benefitted from devoting a smaller proportion of their effort to
short-term mating and a larger proportion to long-term mating. Also,
because of women's concealed fertilization, men were unable to determine
easily whether a child was their biological progeny, who could then proffer
fitness gains. Men ostensibly adapted to this problem of paternity
uncertainty by exerting sexual control over women and developing sexual
jealousy and a motive to control women's sexuality (Daly & Wilson, 1988).
There was of course no parallel problem of maternity uncertainty that would
have induced women to exert sexual control over men.
According to contemporary evolutionary psychologists (e.g., Buss, 1995b;
Buss & Kenrick, 1998), sex differences in many psychological dispositions
arose from the conflict of interest that is displayed in the contrasting
sexual strategies of women and men. Because men competed with other men for
sexual access to women, men's evolved dispositions favor violence,
competition, and risk-taking. Women in turn developed a proclivity to
nurture and a preference for long-term mates who could support a family. As
a result, men strived to acquire more resources than other men in order to
attract women, and women developed preferences for successful, ambitious
men who could provide resources.
The assumption that ancestral humans living in the EEA had a
hunter-gatherer socio-economic system is critical to some of evolutionary
psychologists' claims about sex differences (e.g., Buss, 1995b; Cosmides et
al., 1992; DeKay & Buss, 1992). The idea of a division of labor by which
men hunted while women gathered suggests sex-differentiated pressures
linked to survival and reproduction. Such an ancestral division of labor
might have produced men who were psychologically specialized for hunting
and women who were specialized for gathering. For example, cognitive
abilities could have been affected, with men having the superior spatial
skills that followed from ancestral hunting, and women having the superior
spatial location memory that followed from ancestral gathering (e.g.,
Geary, 1995; Silverman & Eals, 1992; Silverman & Phillips, 1998).
According to this evolutionary perspective, virtually all human sex
differences are readily traced back to the different adaptive problems that
men and women are presumed to have faced during primeval history. Buss and
Kenrick (1998) thus described the evolutionary approach as a "metatheory"
of sex differences and similarities and summarized it as follows: "Men and
women differ in domains where they faced different adaptive problems over
human evolutionary history" (p. 994). These theorists thus derive human sex
differences from heritable adaptations built into the human species in the
EEA. Because these sex differences follow from evolutionary adaptations,
they are predicted to occur as central tendencies of male versus female
behavior. Human behavior would thus be characterized by a deep structure of
sex-differentiated dispositions, producing similar, albeit not identical,
behavioral sex differences in all human societies. Human social structure,
at least in its patriarchal aspects by which men dominate women, would be
an outcome of these evolutionary processes (e.g., B. Smuts, 1995).
Various mediating processes are implied in evolutionary psychology models
of behavioral sex differences. The first and most important involves some
means of retaining effective adaptations in human design and perpetuating
them over time. Thus, sex-differentiated psychological mechanisms and
developmental programs, like other organized, coordinated adaptations, are
"genetic, hereditary, or inherited in the sense that . . . their
structured design has its characteristic form because of the information in
our DNA" (Tooby & Cosmides, 1990a, p. 37; see also Buss, Haselton,
Shackelford, Bleske, & Wakefield, 1998; Crawford, 1998). Some evolutionary
accounts also emphasize that genetic factors trigger biochemical processes
that mediate psychological sex differences, especially by means of sex
differences in hormone production (e.g., Daly & Wilson, 1983; Geary, 1995,
1996; Goldberg, 1993). In addition, sex-typed evolved mechanisms are
translated into behavioral sex differences by various cognitive and
affective processes. Establishing these links requires theoretical
understanding and empirical documentation of the range of processes by
which the genetic factors implicated in innate dispositions might affect
human behavior. Although scientific understanding of these mediational
processes is essential to establishing the validity of the evolutionary
position, such mediation remains relatively uncharted territory (e.g.,
Collear & Hines, 1995).
Evaluation of the Evolutionary Origin Theory
A number of questions can be raised about evolutionary psychology's
account of the origins of sex differences. Some of these questions pertain
to the theory's assumptions about the environment of ancestral humans in
the Pleistocene era. Because adaptations evolved as solutions to past
environmental challenges, an understanding of human's primeval environment
is central to evolutionary theorizing. The ambiguity of scientific
reconstructions of the ancestral past leaves room for evolutionary
scientists to inadvertently transport relatively modern social conditions
to humans' remote past by inappropriately assuming that the distinctive
characteristics of contemporary relations between the sexes were also
present in the Pleistocene era.
To avoid biased reconstructions of the EEA, scientists should seek
independent evidence of the social and physical environments of ancestral
humans. Various bodies of science have some relevance, including
observational studies of other primates, the fossil record, and
ethnographic studies. Each form of scholarship includes sophisticated
theoretical arguments and technical analyses of the relevant data, and the
resulting views of how sex differences may have evolved do not always
coincide between these scientific literatures.
As we explain elsewhere (see Wood & Eagly, 1998), models of human nature
constructed from the behavior of non-human primates do not yield a uniform
picture that reflects key features of sex differences in modern human
societies (see also Travis & Yeager, 1991). Primatologists have noted
considerable variability in male-female relations across primate species
and within species in response to particular environmental conditions
(Fedigan, 1986; Hrdy, 1981; Strier, 1994). Among humans' genetically
closest relatives, bonobos and chimpanzees, male dominance hierarchies are
not primarily structured around access to females but instead are
multidimensional and vary with specific resources (e.g., access to food,
Furthermore, individual males' positions in the dominance hierarchies
derive from a variety of factors, particularly social skills, and not
primarily from size or physical aggression (Strier, 1994). Bonobos' high
levels of sexual activity with both same-sex and mixed-sex partners (de
Waal, 1997) provides an especially striking contrast to many evolutionary
psychologists' assumptions about human sexuality (e.g., Buss & Schmidt,
Similarly ambiguous concerning sex differences are the models of early
human social conditions that paleontologists and paleoanthropologists have
developed from fossil evidence. Particularly troublesome to the
hunter-gatherer reconstruction of ancestral life that is popular with
evolutionary psychologists (e.g., Cosmides et al., 1992; Silverman & Eals,
1992) is the uncertain status of hunting during the Pleistocene era
(Johanson & Edgar, 1996). The available fossil evidence equally or more
strongly suggests scavenging groups (Potts, 1984) with only rudimentary
sex-typing of tasks (Rose & Marshall, 1996). Indeed, anthropological and
historical evidence indicates that simple foraging societies tended to be
relatively egalitarian and that strongly patriarchal social structures
developed as by-products of social and technological innovations (e.g.,
plough agriculture, animal husbandry) that appeared much later than the
Pleistocene era (e.g., Ehrenberg, 1989; Harris, 1993; Leibowitz, 1983;
Lerner, 1986; Sanday, 1981). In general, as social and technological
complexity increased in preindustrial societies, women's status fell
(Schlegel & Barry, 1986; Whyte, 1978).
Observations of more contemporary hunter-gatherer societies, albeit of
uncertain validity for revealing conditions that existed in the EEA, show
great variation in these societies' social organization (Foley, 1996;
Kelly, 1995). Although it is difficult to generalize about extent of male
dominance because dominance in one arena is not necessarily accompanied by
dominance in other arenas, male dominance does not appear to be culturally
universal. As Whyte (1978, p. 167) argued based on an extensive
cross-cultural study of preindustrial societies, "there is substantial
variation from societies with very general male dominance to other
societies in which broad equality and even some specific types of female
dominance over men exist." In summary, scientific efforts to reconstruct
the ancestral past from behavioral studies of primates, the fossil record,
and ethnographic research are not congenial to descriptions of ancestral
life as manifesting those features of male-female relations that are most
critical to the evolutionary psychological analysis (e.g., male effort to
control female sexuality, male dominance, a clear division of labor) (see
Wood & Eagly, 1998).
Given the ambiguity and complexity of scientific findings that might
clarify the adaptive problems that people would have faced in the EEA (see
Betzig, 1998), it is not surprising that there are many alternative
reconstructions of the social structures and reproductive arrangements of
that era. To quote Caporael and Brewer (1991, pp. 3-4), "Propositions
regarding ancestral social structures range from monogamous pair-bonds to
polygynous harems to female-offspring groups to male kin territorial
groups." For example, in an account that departs radically from typical
evolutionary assumptions about parental investment (e.g., Trivers, 1972),
Miller and Fishkin (1997) reasoned that ancestral environments would have
favored very strong male-female pair bonds and high levels of paternal as
well as maternal investment in offspring. Still other evolutionary models
emphasize the shared adaptive challenges faced by ancestral men and women
and argue that humans were likely selected for capabilities such as social
competence and the capacity for culture (see Fiske, Kitayama, Markus, &
Nisbett, 1998; Irons, 1979; MacDonald, 1991). For example, Caporael and
Brewer (1991, 1995) argued that, because small, cooperative groups
constituted ancestral social organization, the fitness gains of both sexes
would have been furthered by characteristics of sociality that promote
coordinated group functioning, such as cooperativeness, loyalty to the
group, and adherence to social norms (see also D. T. Campbell, 1983;
Caporael, 1997; Foley, 1996).
Another problematic issue in evolutionary psychologists' reasoning
concerns the stability of the EEA. Relevant to this issue is Tooby and
Cosmides' (1990b, p. 388) definition of the EEA as "the statistically
weighted composite of environmental properties of the most recent segment
of a species' evolution that encompasses the period during which its modern
collection of adaptations assumed its present form." Although Tooby and
Cosmides argued that this definition does not suggest that the EEA was
uniform or stable, except in a composite statistical sense, evolutionary
psychologists' assumption that evolution of the complex adaptations
relevant to human behavior was a very slow process seems to require
relative stability in the critical features that produced adaptations.
Consistent with this reasoning, Cosmides et al. (1992) maintained that the
considerable amount of time the human species spent in the EEA is evidence
that humans are adapted to this earlier environment and have not changed
appreciably since. Specifically, "the few thousand years since the
scattered appearance of agriculture is only a small stretch in evolutionary
terms, less than 1% of the two million years humans' ancestors spent as
Pleistocene hunter-gatherers. For this reason, it is unlikely that new
complex designs . . . could evolve in so few generations" (p. 5).
In a contrasting view that does not assume any particular pace of
evolutionary response to environmental change, D. S. Wilson (1994) has
argued that evolution is a variable process that depends on factors such as
the intensity of selection, the heritability of traits, and the number of
generations exposed to the evolutionary pressure. Although scientists do
not yet have detailed understanding of the intensity of selection pressures
on humans or the heritability of trait adaptations and nonadaptations,
scientists have shown that evolution can proceed quickly in at least some
species under appropriate conditions (e.g., Grant & Grant, 1993; Weiner,
1994; Zimmerman, 1960) and that some human traits (e.g., the production of
lactase in adulthood and the sickle-cell trait) appeared after the end of
the Pleistocene era (Durham, 1991). Also, Sarich (1997) has argued that the
human racial (i.e., regional) differentiation that is observed today
resulted from changes that occurred in the last 15,000 or so years. As
other scholars have also concluded (e.g., Irons, in press), such claims
raise doubts about the extent to which heritable human psychological traits
were fixed in the Pleistocene era.
Inferring what composites of environmental properties might have been
relevant to selection is difficult, given the abundant changes that
occurred in the human species and its environments during the Pleistocene
era. During the two million years during which human beings were ostensibly
Pleistocene hunter-gatherers (Cosmides et al., 1992), several different
hominid species appeared and disappeared (Irons, in press). It is likely
that a wide variety of foraging groups existed during this time (Foley,
1996) and that these different groups were exposed to extremely diverse
types of adaptive problems (Simpson, 1995). Recurrent ice ages brought
radical shifts in climate and ecology. Furthermore, early homo sapiens
immigrated over the globe from their origins in Africa (Johanson & Edgar,
1996)-a transition that exposed them to varying geographical, climatic, and
ecological environments and likely required considerable shifts in social
organization (Foley, 1996).
Even greater difficulty in identifying stable contingencies of selection is
posed by the recognition that the adaptations characteristic of humans did
not co-evolve simultaneously (Foley, 1996; Lovejoy, 1981). For example,
bipedalism appears to have emerged with Australopithecines, well before
documented tool use and human-like encephalization. According to Tooby and
DeVore (1987), "any substantial change in a major socioecological variable
may reorganize the relationship of many of the others, causing payoffs of
other activities to change markedly, and labile components of adaptive
configurations to alter abruptly" (pp. 205-206). Consequently, the
emergence of each human attribute might have changed a variety of aspects
of hominid life and yielded uniquely structured social organizations
functional only for limited periods of time.
In sum, evolutionary psychologists' argument that humans possess a large
number of universally shared, highly specialized, sexually dimorphic
adaptations requires tenuous assumptions about the rate of human adaptation
and the stability of the contingencies of selection in the EEA. Little
evidence supports the claim that humans as a species evolved during this
earlier period but have not evolved appreciably since or the claim that the
EEA presented consistently structured but sex-differentiated evolutionary
pressures. To the extent that the Pleistocene established the environment
that "defined the adaptive problems the mind was shaped to cope with"
(Cosmides et al., 1992, p. 5), we maintain that the mind should be shaped
to cope flexibly with a very wide range of changing conditions.
In addition to these concerns about the nature and stability of the EEA,
questions can be raised about how evolutionary psychologists go about
identifying the psychological mechanisms and other adaptations in humans.
As illustrated by the work of scholars such as Buss (1995a), Tooby and
Cosmides (1992), and Symons (1992), evolutionary psychologists identify
adaptations by relying "on informal arguments as to whether a presumed
function is served with sufficient precision, economy, efficiency, etc. to
rule out pure chance as an adequate explanation" (Williams, 1966, p. 10).
To identify the function of biological mechanisms, evolutionary
psychologists assume "that functional design is something that can be
intuitively comprehended by an investigator and convincingly communicated
to others" (Williams, 1996, p. 260). Evolutionary explanations that reflect
this approach consist of an informal analysis of the functional relations
served by a particular psychological mechanism along with the construction
of a convincing story about how the adaptation might have made an efficient
contribution to genetic survival or some other goal contributing to
reproduction (Gould, 1980; Williams, 1966). Brandon (1990, p. 180) labeled
these functional analyses "speculative how-possibly explanations," and
Caporael (1997, p. 295) warned against these analyses' pitfalls of
"confirmatory biases, the seductiveness of scenario-thinking, the problems
posed by the availability and representativeness heuristics, and the
biasing effects of vividness in descriptions of the past."
Given the reliance of this method on scientists' insights about functions,
special difficulties arise in distinguishing adaptations from several other
products of evolution postulated by evolutionary scientists-namely, from
(a) features that originally had utility for one function but were
subsequently co-opted to fulfill a new function, (b) features that were
originally mere by-products of adaptations but may or may not have been
subsequently co-opted to fulfill a function, and (c) features that were
random and thus did not initially evolve to fulfill a function but may or
may not have been subsequently co-opted to fulfill a function (see Buss et
al., 1998; Gould, 1991; Williams, 1966). These more refined distinctions
considerably complicate the task of formulating hypotheses about the
evolutionary origins of behavior, because particular benefits to the
organism hypothesized for early or subsequent environments do not provide a
clear-cut basis for identifying evolved mechanisms. Moreover, the products
of evolution must be distinguished from the products of cultural change.
Behaviors that provide efficient engineering solutions to problems of
reproduction and survival can arise from inventive trial-and-error among
individuals who are genetically indistinguishable from other members of
their living groups; such beneficial behaviors are then imitated and
transmitted culturally. Despite these complexities, Tooby and Cosmides
(1990b, p. 401) proposed that "every behavior, adaptive or maladaptive, is
the product of adaptations (or other linked aspects of underlying design)
and hence is patterned by the structure of these adaptations." Given such a
viewpoint, it is not surprising that specialized mechanisms have
proliferated in current evolutionary models. If the result is a long list
of adaptations, each applicable in its own domain, this proliferation
becomes reminiscent of some of the pitfalls of earlier instinct theories.
The most convincing evidence that a behavioral pattern reflects an
adaptation would be that individuals who possessed the adaptation enjoyed a
higher rate of survival and reproduction than individuals who did not
possess it. However, such evidence is difficult, if not impossible, to
produce. Because evolved mechanisms in humans emerged in relation to past
selection pressures, present reproductive advantage does not necessarily
reflect past advantage, and evolutionary psychologists have warned against
relying on measures of current reproductive success to validate postulated
adaptations (Buss, 1995a; Tooby & Cosmides, 1992). Despite these
reservations, it is not uncommon to find evolutionary psychologists
invoking current fertility data to validate evolutionary claims and even
arguing that such evidence can be persuasive (Betzig, 1998). For example,
to support the ideas that men invested less in offspring than women and
that a strategy emphasizing quantity of sexual partners was adaptive for
men, Buss (1996) cited data from a contemporary foraging society in which
the variance in number of children is higher among men than among women
(see also Perusse, 1993). In our view, it is reasonable to conclude that
modern fertility data provide uncertain evidence for adaptations, given
that past adaptations are not necessarily functional in current society.
This uncertainty is part of the broader intellectual predicament that
follows from the intuitive identification of what might have been adaptive
for ancestral humans and from the analysis of how these postulated
adaptations might interact with current environmental factors to generate
Social Structural Theory as an Origin Theory of Sex Differences
Most social scientists locate the ultimate cause of sex differences, not
in evolved psychological dispositions that are built into the human psyche,
but in the contrasting social positions of women and men. In contemporary
American society, as in many world societies, women have less power and
status than men and control fewer resources. This feature of social
structure is often labeled gender hierarchy or in feminist writing it may
be called patriarchy. In addition, as the division of labor is realized in
the United States and many other nations, women perform more domestic work
than men and spend fewer hours in paid employment (Shelton, 1992). Although
most women in the United States are employed in the paid workforce, they
have lower wages than men, are concentrated in different occupations, and
are thinly represented at the highest levels of organizational hierarchies
(Jacobs, 1989; Reskin & Padavic, 1994; Tomaskovic-Devey, 1995). From a
social structural perspective, features of social organization, in
particular gender hierarchy and the sexual division of labor, are the root
cause of sex-differentiated behavior.
The determinants of the distribution of men and women into social roles are
many (see Wood & Eagly, 1998) and include the biological endowment of women
and men. The sex-differentiated physical attributes that influence role
occupancy include men's greater size and strength, which would give them
priority in nonmechanized warfare and in jobs involving certain types of
strenuous activity, especially involving upper body strength. These
considerations of men's greater size and strength are less important in
societies in which few occupational roles demand these attributes, such as
post-industrial societies in particular. Also important in relation to role
distributions are women's childbearing and in many societies their activity
of lactating for long periods of time; these obligations would give them
priority in roles involving the care of very young children and conflict
with roles that require extended absence from home and uninterrupted
activity. These considerations of women's reproductive activity are less
important in societies with low birthrates, less reliance on lactation for
feeding infants, and greater reliance on nonmaternal care of young
children. Thus, physical sex differences, in interaction with other
variables, influence the roles held by men and women (see Wood & Eagly, 1998).
The differing distributions of men and women into social roles form the
basis for a social structural metatheory of sex differences, just as
evolutionary theory provides a metatheory. The major portion of the social
structural theory follows from the typical features of women's roles versus
men's. Thus, the first metatheoretical principle derives from the greater
power and status that tends to be associated with male-dominated roles and
can be succinctly stated as follows: Women's adaptations to roles with
lesser power and status in society produce a pattern of behavior that
might be described as subordinate, and men's adaptations to greater power
and status produce more dominant behavior (Ridgeway & Diekema, 1992; P.
Stewart, 1988). Subordinate behavior is more compliant to social influence,
less overtly aggressive, and more cooperative and conciliatory. Dominant
behavior is controlling, assertive, relatively directive and autocratic,
and may involve sexual control. In this view, men's sexual control over
women is but one example of male dominance.
The second metatheoretical principle follows from the differing balance of
activities associated with the typical roles of each sex. Women and men
seek to accommodate sex-typical roles by acquiring the specific skills and
resources linked to successful role performance and by adapting their
social behavior to role requirements. A variety of sex-specific skills and
beliefs arise from men's and women's typical family and economic roles,
which in many societies can be described as resource provider and
homemaker. Women and men seek to accommodate to these roles by acquiring
role-related skills, for example, women learning domestic skills such as
cooking and men learning skills that are marketable in the paid economy.
The social behaviors associated with these roles have been characterized in
terms of the distinction between communal and agentic characteristics
(Bakan, 1966; Eagly, 1987). Thus, women's accommodation to the domestic
role and to female-dominated occupations produces a pattern of
interpersonally facilitative and friendly behaviors that can be termed
communal. In particular, the assignment of the majority of child-rearing to
women encourages communal behaviors, including nurturant behaviors that
facilitate care for children and other dependent individuals. The
importance of close relationships to women's nurturing role favors the
acquisition of superior interpersonal skills and ability to communicate
nonverbally. In contrast, men's accommodation to the employment role,
especially to male-dominated occupations, produces a pattern of assertive
and independent behaviors that can be termed agentic (Eagly & Steffen,
1984). This argument is not to deny that paid occupations show wide
variation in the extent to which they favor more masculine or feminine
qualities. Suggesting that sex-differentiated personal qualities may be
shaped by paid occupations are demonstrations that to the extent that
occupations are male-dominated, success in them is perceived to follow from
agentic personal qualities, whereas to the extent that occupations are
female-dominated, success in them is perceived to follow from communal
personal qualities (Cejka & Eagly, in press; Glick, 1991).
In summary, two metatheoretical principles of sex differences follow from
the contrasting positions of men and women in the social structure: One
principle invokes the greater status that is typical of men's roles, and
the second principle recognizes the differing types of activities that are
typical of women's versus men's roles, which in many societies reflect
resource provider and homemaker roles. Although these principles provide a
general account of virtually all human sex differences, understanding their
variability across situations and individuals requires additional
principles (e.g., Deaux & Major, 1987).
Although the differing assignments of women and men to social roles are
considered to be the basic underlying cause of sex-differentiated social
behavior, their impact on behavior is mediated by psychological and social
processes. One statement of mediational links is in social role theory
(Eagly, 1987; Eagly & Wood, 1991), which implicates gender roles as a
proximal cause of sex differences. By this account, differential role
occupancy fosters gender roles by which each sex is expected to have
characteristics that equip it for its sex-typical roles. Because gender
roles encompass desirable as well as typical attributes of men and women,
the attributes that are thought to be desirable and appropriate to women
and men depend on the activities that each sex is expected to perform.
The expectancies associated with gender roles act as normative pressures
that foster behaviors consistent with sex-typical work roles. Gender roles
are emergents from the productive work of the sexes; the characteristics
embodied in these roles become stereotypic of women or men. To the extent
that women more than men occupy roles that demand communal behaviors,
domestic behaviors, or subordinate behaviors for successful role
performance, such tendencies become stereotypic of women and are
incorporated into a female gender role. To the extent that men more than
women occupy roles that demand agentic behaviors, resource acquisition
behaviors, or dominant behaviors for successful role performance, such
tendencies become stereotypic of men and are incorporated into a male
gender role. Gender roles facilitate the activities typically carried out
by people of each sex. For example, the expectation that women be
other-oriented and compassionate facilitates their nurturing activities
within the family as well as their work in many female-dominated
occupations (e.g., teacher, nurse, social worker).
To the extent that these normative expectations about behavior appropriate
to women and men become internalized as part of individuals' self-concepts
and personalities, people can be described as forming dispositions or
traits that are consistent with gender roles (Feingold, 1994; Wood,
Christensen, Hebl, & Rothgerber, 1997).Yet, people may also behave
consistently with their gender roles without necessarily acquiring
dispositions that foster such behavior. Congruent with empirical research
on the behavioral confirmation of stereotypes and other expectancies (see
Olson, Roese, & Zanna, 1996), people communicate gender-stereotypic
expectations in social interaction and can directly induce the targets of
these expectations to engage in behavior that confirms them (e.g., Skrypnek
& Snyder, 1982; Wood & Karten, 1986).
Gender roles, viewed as shared expectations that apply to individuals on
the basis of their socially identified sex (Eagly, 1987), co-exist with
specific roles based on factors such as family relationships (e.g., mother,
son) and occupation (e.g., secretary, firefighter). Role theorists maintain
that, because specific social roles are very constraining, sex differences
would tend to erode when men and women occupying the same specific social
role are compared (e.g., Eagly & Johnson, 1990). However, gender roles
ordinarily continue to have some impact on behavior, despite the
constraints of specific roles. For example, Gutek and Morasch (1982) argued
that gender roles spill over to workplace roles and cause people to have
different expectations for female and male occupants of the same workplace
role. Moreover, experimental evidence (e.g., Hembroff, 1982) suggests that
people combine or average the expectations associated with specific roles
and more diffuse roles such as gender roles in a manner that weights each
expectations according to its relevance to the task at hand.
The social structural perspective provides a broad theoretical outline
within which many social scientific theories of sex-differentiated behavior
can be placed. These theories focus on different aspects of the processes
by which societies produce sex-differentiated behavior, and many theories
have spawned detailed predictions and a substantial body of empirical
research (see Beall & Sternberg, 1994; Canary & Dindia, 1998; England &
Browne, 1992). For example, developmental psychologists have studied
socialization in the family, school, and peer group. Social psychologists
have examined the impact of gendered self schemas, men's greater status,
sex-differentiated expectations about behavior, and gendered patterns of
social interaction. Sociologists have implicated organizational factors
such as discriminatory employment practices, societal factors such as men's
greater ownership of capital, and cultural factors such as the ideologies
that legitimize gender inequality. Social scientists have thus provided an
array of interrelated theories, each of which illuminates certain aspects
of the complex of processes by which sex-differentiated behavior is produced.
In sum, in social structural accounts, women and men are differently
distributed into social roles, and these differing role assignments can be
broadly described in terms of a sexual division of labor and gender
hierarchy. This division of labor and the patriarchal hierarchy that
accompanies it provide the engine of sex-differentiated behavior because
they trigger social and psychological processes by which men and women seek
somewhat different experiences in order to maximize their outcomes within
the constraints that societies establish for people of their sex. Sex-typed
social roles are the underlying determinants of men's and women's social
behavior, but the impact of these roles is mediated by social and
psychological processes. The essential idea of this approach is the
functional principle that people come to expect that women and men possess
those characteristics that allow them to carry out their sex-typical
productive work. Because sex differences are adjustments to the differing
restrictions and opportunities that a society provides for its men and
women, the differences that are observed today reflect existing social
conditions and thus are thoroughly modern.
Evaluation of the Social Structural Origin Theory
A number of criticisms have been leveled against the social structural
theory of sex differences and more specifically against social role theory
(see Archer, 1996; Buss, 1996). At least some evolutionary psychologists
have expressed skepticism in some of their writings that culture and social
structure could have any causal role at all in relation to sex differences.
Culture and social structure are seen as abstractions that cannot be
responsible for behavioral differences, and causation is judged unclear or
implausible when it is located in factors such as men's and women's
differing social roles. For example, Buss (1995a) wrote, "'culture,'
'learning,' and 'socialization' do not constitute explanations, let alone
alternative explanations to those anchored in evolutionary psychology" (p.
14). In contrast, the great majority of social scientists have no
difficulty whatsoever in accepting culture and social structure as causal
in relation to human behavior. Culture is often thought to exist separately
from genetic evolution (e.g., D. T. Campbell, 1975), although theories of
gene-culture coevolution treat culture as interdependent with genetic
evolution (e.g., Barker, 1989; Durham, 1991). Culture, as knowledge,
beliefs, and evaluations shared among members of a society, and social
structure, as "persisting and bounded patterns of behavior and interaction
among people or positions" (House, 1995, p. 390), can be held causally
responsible for the content of social roles. Social roles, which are
themselves social constructions, can induce behavior because they foster
role-appropriate responding through a variety of more proximal mechanisms.
Another criticism is that in social structural theories, individuals are
treated as mere passive receptacles of the roles they are assigned (Buss,
1996). Although social scientists often do refer to people as "assigned" to
roles, the processes by which role assignment occurs are not necessarily
passive. On the contrary, social and organizational psychologists have
demonstrated that these processes are complex and dynamic (e.g., Kerckhoff,
1995). Organizations, for example, must initially select appropriate
entry-level candidates for organizational roles from among persons who seek
out these roles. Organizations establish systems for teaching and
maintaining appropriate role behavior; individuals within organizations
continually adjust their role performance based on performance feedback,
others' expectations, and their own goals (see Pfeffer, 1998). In deciding
whether to attempt to assume particular roles at all, individuals take
their own attributes, skills, and personal preferences into account,
although in some cultural contexts some roles are imposed on people
regardless of their own preferences (e.g., the practice of early betrothal
of girls). Yet, roles are not typically assigned to individuals
arbitrarily, as if they were passive actors in the social system. Rather,
social systems are arranged to shape people's self-concepts, skills,
beliefs, and values so that the majority of people actively seek out
experiences that help them to become appropriate occupants of existing
social roles by meeting the expectations of these roles. The active nature
of role assignment becomes apparent when some individuals fail to master
even the society's most basic roles. For example, Bernard (1981) provided
poignant descriptions of men who failed to accommodate successfully to the
role of provider in its heyday and dropped out to become tramps or hobos.
Evolutionary psychologists also criticize gender roles as "essentially
arbitrary" (Buss, 1996, p. 19) or as arising by "historical accident"
(Archer, 1996, p. 915). This perception of arbitrariness fails to take into
account that gender roles are very firmly rooted in a society's division of
labor. The content of gender roles is not arbitrary but is determined by
the social system, economy, and shared cultural beliefs. Roles must thus
facilitate the economic endeavors of a society, if its members are to
prosper and survive. Therefore, different types of role systems become
effective under differing circumstances. For example, in industrial
economies, many roles are organized by a market pricing system that takes
into account factors such as ownership of property and contribution to
production (see Fiske, 1992). Psychologists who adopt a social structural
perspective do not themselves provide a theory of how and why social
organization changes over time. Instead, appropriate analytical frameworks
have been developed by scholars in other disciplines (e.g., Diamond, 1997;
Toynbee, 1931-1961). However, understanding the principles by which women
and men distribute themselves into a society's roles is part of the agenda
of social psychologists (Wood & Eagly, 1998) as well as other social
scientists (e.g., Ehrenberg, 1989; Harris, 1993; Lerner, 1986; Sanday,
1981). Moreover, the structurally oriented social psychologist assumes
that, whatever a society's role system is, social and psychological
processes ensue by which the majority of people accommodate themselves to it.
A related criticism is that, from a social structural perspective,
"differences between cultures are random with respect to evolutionary
hypotheses and therefore that, for example, sex differences should occur as
frequently in one direction as the other" (Tooby & Cosmides, 1989, p. 37).
However, social structuralists would not predict random variation in sex
differences across societies. As Wood and Eagly (1998) outline, variation
in the roles of men and women across societies depend on a variety of
factors, including men's greater physical strength, women's reproductive
activities, and the activities required by a society's economy and social
organization, which in turn reflect technological developments and the
current ecology. Because these factors that underlie sex-typed social
structures are not randomly distributed, certain types of social
arrangements are more common than others, and sex differences appropriate
to the common arrangements should be more frequent than reversals of these
differences. The social structuralist would go further and predict the
conditions under which differences would appear and disappear (see
subsequent discussion of mate selection).
Another criticism of the social structural approach is that it treats the
minds of women and men as identical except by virtue of the constraints
that follow from externally assigned roles (Buss, 1996). While believing
that the issue of whether female and male brains are intrinsically
different is best addressed by scientific research, we acknowledge that a
purely social structural perspective does indeed maintain that differences
in the minds of women and men arise primarily from experience and
socialization. Moreover, the diversity of behaviors and skills exhibited by
men and women across societies and within societies suggests that in most
domains humans' attributes are extremely plastic and minimally constrained
by initial, intrinsic sex differences. Yet, this perspective is fully
compatible with the idea that people possess evolved facilities, such as
for language, that develop in predictable ways in appropriate environments.
The typical social structuralist begins with the assumption that the great
majority of these basic psychological facilities are the same in women and
men and that the placement of each sex in the social structure of a given
society molds behavior into sex-differentiated patterns.
Sex Differences Predicted from
Evolutionary Psychology and Social Structural Theory
All theories of sex-differentiated behavior should be evaluated by their
ability to predict the differences and similarities between female and male
behavior. Social structural theories of sex differences are associated with
predictions about a wide range of social behaviors (e.g., social influence,
social interaction, prosocial and antisocial behavior, nonverbal behavior,
leadership). Because most of these behaviors have not been studied
extensively from an evolutionary perspective, they do not provide an
appropriate ground for comparing the two approaches. The most reasonable
area for this comparison of theories is human mating behavior, especially
sex differences in mate selection criteria. Evolutionary predictions have
been articulated especially clearly for mating activities, and, as we
explain below, these behaviors can also be used to test a social structural
perspective. Furthermore, empirical findings concerning the mate selection
preferences of men and women have been well established for many years in
the literature on the sociology of the family (e.g., Coombs & Kenkel,
1966). Powers' (1971) summary of 30 years of prior research concluded that,
at least in the United States, women generally prefer mates with good
earning potential, whereas men prefer mates who are physically attractive
and possess good domestic skills. Furthermore, women typically prefer a
mate who is older than them, whereas men prefer a mate who is younger.
Feingold's (1991, 1992a) meta-analyses established that the sex differences
in valuing potential mates' earning potential and physical attractiveness
are robust. Subsequent research, notably Sprecher, Sullivan, and Hatfield's
(1994) excellent study of a national probability sample of single adults,
provided further confirmation of the sex differences in age preferences as
well as in valuing earning potential and physical attractiveness (but see
mixed evidence in Regan & Berscheid, 1997).
Evolutionary Models of Mate Preference
Modern evolutionary psychologists have adopted mate preferences as
signature findings of their analysis. Women's valuing of mates' resources
and men's valuing of mates' youth and physical attractiveness are thought
to arise from the different parental investment of the sexes that was
outlined in Trivers' (1972) sexual selection theory. It is commonly argued
that women, as the more investing sex, seek mates with attributes to
support their parenting efforts. However, human mate selection does not
follow a strict version of Trivers' (1972) males-compete-and-females-choose
model, because among humans selection is a product of the behavior of both
sexes (a process Darwin  called "dual selection"). In Buss's (1989a)
account, men's preferences derive from the additional dynamic that, because
of women's time-limited reproductive capacity, men seek mates with
attributes that suggest they possess such capacity. Yet, to the extent that
human mating conforms to Trivers' theory and that women are the more
investing sex, women's preferences should be the primary selective force in
human mating, and men's preferences should be less important. In an
analysis that builds on sexual selection theory yet accords male and female
preferences relatively equal weight, Kenrick and Keefe (1992) suggest that
human males and females both invest heavily in offspring and are selective
about potential mates but that the sexes invest different kinds of
resources. This resource differential is thought to underlie sex
differences in mate preference. In particular, "men invest relatively more
indirect resources (food, money, protection, and security), and females
invest relatively more direct physiological resources (contributing their
own bodily nutrients to the fetus and nursing the child)" (Kenrick & Keefe,
1992, p. 78). As a result, women prefer mates who can provide indirect
resources, and men prefer healthy mates with reproductive potential.
Despite this general consensus among contemporary evolutionary
psychologists about the qualities women and men prefer in mates, a broader
sampling of evolutionary scientists' writings reveals considerable
variability in their opinions. For example, E. O. Wilson (1975, p. 569)
argued that women's choices would be directed toward "hunting prowess,
leadership, skill at tool making, and other visible attributes that
contribute to the success of the family and the male band." In contrast,
Darwin (1871) thought that women in primeval times chose men who were
handsome defenders and providers; "women would generally choose not merely
the handsomest men, according to their standard of taste, but those who
were at the same time best able to defend and support them" (Darwin, 1871,
p. 585). Darwin expressed skepticism, however, about how applicable the
processes of sexual selection are to modern human societies. He argued that
sexual selection was more powerful among early humans, who were guided by
instinctive passions, than among contemporary members of society, who show
greater foresight and reason in mating behavior. In fact, Darwin (1871)
maintained that "civilized men are largely attracted by the mental charms
of women, by their wealth, and especially by their social position" (p. 178).
From a comparative perspective on sexual selection, preference for
resources is likely to depend on a variety of contextual factors, including
the pattern of resources controlled by each sex in a community (R. W.
Smuts, 1989). In human societies in which most of the resources are
controlled by men, women are more likely than men to prefer mates with
resources. In contrast, among nonhuman primates, females usually support
themselves and their young with little male
help, and in hunter-gatherer societies and many agricultural societies,
women do a great deal of the productive work and supply many of the
economic resources for their families. Although Smuts's views remain
controversial (see Buss, 1991), he suggested that, given these social
organizations, there are "strong reasons to suspect that a preference for
economically successful mates might have a bigger genetic payoff for males
than for females" (R. W. Smuts, 1989, p. 33).
Social Structural Models of Mate Preferences
From a social structural perspective, women and men are sought after as
mates to the extent that they are suited to fulfill the marital roles of
their society. The critical assumption about the underlying psychology of
mate selection is merely that people attempt to maximize their utilities
with respect to mating choices, just as they do with respect to other
decisions. Consistent with these ideas, Becker's (1976) economic analysis
of mating decisions characterized marriage as occurring between
utility-maximizing men and women who can reach an equilibrium with a
variety of types of exchanges, including, for example, an exchange between
men's wages and women's contributions in terms of household production and
other attributes such as education and beauty. This cost-benefit analysis
of mating appears even on occasion in the writings of evolutionary
scientists. For example, Tattersall (1998, p. 207) maintained that
behavioral regularities such as sex differences in mate selection criteria
are as likely due to "rational economic decisions" as inherited
predispositions, and Hrdy (1997, p. 29) wrote that "a woman's preference
for a wealthy man can be explained by the simple reality that in such
societies males monopolize ownership of productive resources."
The outcomes that are perceived to follow from mating decisions depend on
the marriage and family arrangements that exist within this structure. To
the extent that women and men occupy marital and family roles that entail
distinctively different responsibilities and obligations, they should
select mates according to criteria that reflect these divergent
responsibilities and obligations. Consider, for example, the family system
based on a male provider and a female domestic worker. This system became
common in industrial economies and is still prevalent in many world
societies. According to Bernard (1981), in the United States these roles
arose approximately in the 1830s. This male provider system remained
dominant in the United States until the 1970s, and its gradual and
continuing demise was marked in 1980 by the abandonment by the U.S. Census
of the practice of automatically declaring the male the head of the
household. To the extent that societies have a division of labor between
female domestic responsibility and male contribution to the economy, women
maximize their outcomes by seeking a mate who is likely to be successful in
the economic, wage-earning role. In turn, men maximize their outcomes by
seeking a mate who is likely to be successful in the domestic role.
The sex differences in the preferred age of mates also can be understood
as part of the general tendency of men and women to seek a partner likely
to provide a good fit to their society's sexual division of labor and
system of marital roles. Specifically, the marital system based on a male
breadwinner and a female homemaker favors the age gap in marriage. In
general, marriageable women who are younger than their potential mates have
lesser wages, social status, and education and knowledge than women who are
the same age. With the combination of a younger, less experienced woman and
an older, more experienced man, it would be easier to establish the power
differential favoring men that is normative for marital roles defined by a
male breadwinner and a female domestic worker (Lips, 1991; Scanzoni &
Szinovacz, 1980; Steil, 1997). Moreover, assuming that women, as
utility-maximizing individuals, act to maximize their perceived outcomes,
younger women are more likely to view marriage as a good outcome, compared
with alternative life situations, and are more likely to accept the role of
domestic worker in a marriage. In complementary fashion, older men are more
likely to have acquired the economic resources that make them good
candidates for the provider role. The older man and younger woman thus fit
more easily than same-age partners into the culturally expected pattern of
good provider and skillful domestic worker.
Cross-Cultural Evidence for Sex Differences in Mate Preferences
The modern evolutionary psychology predictions that women select for
resources and older age and men for attractiveness and younger age have
received support from cross-cultural studies of mate preference (Buss,
1989a; Buss et al., 1990; Kenrick & Keefe, 1992). Buss's impressive study
in 37 cultures of the characteristics that people desire in mates suggested
that, consistent with evolutionary perspectives, these sex differences in
mate preferences emerge cross-culturally (Buss, 1989a; Buss et al., 1990).
Also, Kenrick and Keefe (1992) examined age differences in mates in five
countries and across various time periods in the twentieth century and
concluded that all provided evidence of sex-related age preferences in
mates. Specifically, for dating and marriage, women prefer older men and
men prefer younger women, although men's preference for younger age is
moderated by men's age, with teenage boys preferring same-aged girls.
Based on these investigations, evolutionary accounts have emphasized the
cross-cultural commonality in women's preference for resources and older
age and men's for attractiveness and youth. According to Buss (1989a) and
Tooby and Cosmides (1989), uniformity across diverse cultures and social
circumstances suggests powerful sex-differentiated evolved mechanisms that
reflect an innate, universal human nature. Kenrick and Keefe (1992)
similarly argued that "invariance across cultures is evidence that supports
a species-specific, rather than a culture-specific, explanation" (p. 76).
Despite evidence for cross-cultural commonality, these investigations also
yielded evidence for cultural variation in sex differences in mate
selection criteria. For example, Kenrick and Keefe (1992) found that the
preference for younger wives was evident among Philippine men of all ages,
but only among older (i.e., 30+) men in the United States. It is not
useful, however, to debate whether these studies yielded mainly
cross-cultural uniformity or variability. The simple existence of
uniformity or variability does not provide a definitive test of either the
evolutionary or the social structural origin theory. Although evolutionary
psychologists emphasize uniformity and social structural theorists
emphasize variability, both perspectives have some power to explain both of
these cross-cultural patterns. To account for uniformity, social
structuralists can point to similarities in the sexual division of labor in
the studied societies and argue that these produce comparable sex
differences across societies. In particular, despite the fact that Buss et
al. (1990) and Kenrick and Keefe (1992) produced the most cross-culturally
comprehensive findings that are available concerning mate preference, they
did not sample world societies in representative fashion. As Buss (1989a)
noted, his 37 cultures were biased toward urbanized cash-economy cultures,
with 60% from Europe and North America. Furthermore, respondents selected
from each society tended to be young, comparatively well-educated, and of
relatively high socio-economic status. To the extent that these societies
share features linked to the definitions of men's and women's roles and to
the extent that the respondents were similarly placed in these societies'
social structures, commonality in the sex differences that follow from
social structure should characterize these societies.
To account for cross-cultural variability, both evolutionary and social
structural origin theories recognize that developmental processes and
social factors that are unique to each society direct behavior in ways that
can yield variability in sex differences across cultures. Beyond this
insight that some evidence of cross-cultural variability would not surprise
theorists in either camp, the particular pattern of cross-cultural
variation provides an informative test of the mechanisms underlying sex
differences. Specifically, the social structural argument that the sexual
division of labor within a given society is responsible for sex differences
in social behavior yields predictions concerning cross-cultural variability
in mate preferences.
In the nations included in Buss et al.'s (1990) cross-cultural sample,
whose economies range from agrarian to post-industrial, some cultures would
still be strongly marked by this division of labor between the provider and
domestic worker, whereas other cultures have departed from it. In advanced
economies like the United States, women have entered the paid labor force
and spend a smaller proportion of their time in domestic labor (Haas, 1995;
Shelton, 1992). Although the tendency for men to increase their hours of
domestic work is much more modest, the lives of men and women become more
similar with greater gender equality. Therefore, people of both sexes
should lessen their emphasis on choosing mates whose value is defined by
their fit to the division between domestic work and earning in the wage
economy. Even in post-industrial economies such as the United States,
however, the sex-typed division of labor remains in modified form, with men
devoting longer hours than women to wage labor and women devoting longer
hours to domestic work (e.g., Ferree, 1991; Presser, 1994; Shelton, 1992).
Therefore, the social structural prediction is that the sex differences in
mate selection criteria that follow from the male-female division of labor
should be substantially weakened in societies characterized by greater
gender equality, albeit still present to the extent that complete equality
has not been achieved.
Some support for this social structural interpretation was provided in
Glenn's (1989) reanalysis of Buss and colleagues' (1990) 37 cultures data,
which examined whether the sex differences in mate preferences at a
societal level varied with indexes of economic development. Although in
more developed countries both sexes placed less importance on financial
prospects and preferred a smaller age difference between self and spouse,
the relationships to sex differences in provider characteristics were
nonsignificant. However, because development is only a proxy for equality
of the sexes, Glenn's test of the social structural hypothesis must be
regarded as preliminary. In another effort, Buss (1989a) correlated A. J.
Stewart and Winter's (1977) indexes of gender equality with societies' mean
sex difference in the value assigned to earning capacity in a subsample of
30 of the 37 cultures. Although these correlations were nonsignificant, the
reduced sample as well as possible limitations of the Stewart and Winter
indexes led us to believe that it would be worthwhile to produce a more
thorough test of the hypothesis that sex-typed preferences for mates lessen
with greater structural equality between the sexes.
Reanalysis of Buss et al.'s (1990) 37 Cultures Data
We reanalyzed Buss and his colleagues' (1990) 37 cultures data to evaluate
whether the division of labor within a society could explain the mate
preferences of men and women. Buss et al. (1990) examined samples of young
people in 37 cultures drawn from 33 countries that were widely dispersed
around the world. In each culture, two questionnaire measures assessed
preferences for a wide range of characteristics that might be desired in
mates: (a) one instrument obtained rankings of a set of 13 characteristics
according to "their desirability in someone you might marry"; (b) the other
instrument obtained ratings on a 4-point scale of each of 18
characteristics on "how important or desirable it would be in choosing a
mate" (Buss et al., 1990, p. 11). Buss and his collaborators represented
each culture by men's and women's mean ranking of each of the 13 mate
selection criteria and mean rating of each of the 18 criteria.
Our reanalysis confirmed Buss et al.'s (1990) conclusion that women placed
more value than men on a mate's wage-earning ability. Furthermore,
consistent with the greater domestic responsibility of women than men in
most cultures, the data also showed that men valued good cook and
housekeeper more than women did, a sex difference that has received little
attention from evolutionary psychologists. When averaged across the 37
cultures, this sex difference was of comparable magnitude to that obtained
on attributes emphasized by evolutionary psychologists. Specifically, in
Buss et al.'s (1990) ranking data, good earning capacity produced the
largest sex difference among the 13 criteria, followed by physically
attractive in second place, and good housekeeper in third place. In the
rating data, financial prospect produced the largest difference among the
18 criteria, followed by housekeeper and cook in second place, and good
looks in third place. Other criteria that might seem relevant to the
evolutionary argument (e.g., ambition and industriousness, good health)
produced considerably smaller sex differences. The appropriateness of
focusing on the criteria pertaining to earning ability and domestic skill
within the Buss et al. data is also supported by the good agreement across
the ranking and rating data sets for sex differences in the valuation of
financial provider, r (33) = .77, p < .001, and domestic skill, r (33) =
.68, p < .001(whereas the agreement in the valuation of looks was
considerably poorer, r (33) = .33, p < .10). In addition, as Buss et al.
(1990) reported, the sex difference in the preferred age of mates was fully
intact in the 37 cultures data.
Additional evidence for the social structural predictions emerged when we
evaluated the pattern of sex differences in preferences across societies.
Consistent with the division of labor principle, a substantial relation
emerged between the sex difference in valuing a spouse's domestic skills
and the sex difference in valuing a spouse's capacity to provide a good
income. Specifically, based on the ranking measure, the sex differences in
the good earning capacity criterion and the good housekeeper criterion were
correlated across the cultures, r (33) = .66, p < .001. Based on the rating
measure, the correlation between the sex differences in the financial
prospect criterion and the housekeeper-cook criterion was similar, r (35) =
.42, p < .01. These positive correlations indicate that, to the extent that
women more than men reported seeking a mate who is a good breadwinner, men
more than women reported seeking a mate who is a good homemaker. In
addition, the sex difference in the preferred age of one's spouse bore a
positive relation to the sex difference in preference for a good earner, r
(35) = .34, p < .05 for the ranking data and r (35) = .36, p < .05 for the
rating data. Similarly, the sex difference in preferred age also bore a
positive relation to the sex difference in preference for a good
housekeeper and cook, r (35) = .58, p < .001 for the ranking data and r
(35) = .60, p < .001 for the rating data. These relationships show that to
the extent that the sex difference in the preferred age of spouses was
large, women more than men preferred mates who were good providers and men
more than women preferred mates who were good domestic workers. The
division of labor provides the logic of all of these relationships: Women
who serve in the domestic role are the complement of men who serve as
breadwinners, and the pattern of older husbands and younger wives
facilitates this form of marriage.
As we noted in the prior subsection, the key social structural prediction
is that men's tendency to select wives for domestic skill and younger age
and women's tendency to select husbands for earning capacity and older age
diminish as women and men assume more similar roles in the wage economy and
the family and societies thereby attain a higher level of gender equality.
To test this hypothesis about role similarity lessening these sex
differences, we represented societies' gender equality in terms of archival
data available from the United Nations (United Nations Development
Programme, 1995). These data were available for most of the 37 cultures
studied by Buss et al. (1990). Of the many societal attributes compiled by
United Nations' researchers, the most relevant to our hypothesis is the
aggregate gender empowerment measure, which represents the extent to which
women participate equally with men in economic, political, and
decision-making roles. This index increases as (a) equality is approached
in women's percentage shares of administrative and managerial jobs and
professional and technical jobs, (b) women's percentage share of
parliamentary seats rises, and (c) women's proportional income share
approaches parity with men's. As assessed by this index, Norway has the
greatest equality, followed by Sweden, Denmark, Finland, New Zealand,
Canada, and the United States.
The gender-related development index is another useful indicator of
societal-level gender equality. It increases with a society's basic
capabilities to provide health (i.e., life expectancy), educational
attainment and literacy, and wealth, but imposes a penalty for gender
inequality in these capabilities. Whereas the gender-related development
measure reflects equality in basic access to health care, education and
knowledge, and income, the gender empowerment measure is a purer indicator
of equal participation in economic and political life. In the set of 37
cultures, the gender empowerment index and the gender-related development
index were significantly related, r (33) = .74, p < .001, and both of these
indexes were moderately correlated with general indexes of human
development and economic development. One limitation of the gender
empowerment measure and the gender-related development index is that they
are based on data from the early 1990s. Because the Buss et al. (1990) data
were collected in the mid-1980s, these indexes are from a slightly later
time period, but the relative position of the cultures should remain
approximately the same.
For the Buss et al. (1990) 37 cultures data, we calculated the
correlations of these indexes with the sex differences in valuing a mate as
a breadwinner and as a domestic worker-the two criteria most relevant to
the traditional division of labor. These correlations for the ranking and
the rating data are displayed in Table 1. The critical social structural
prediction was supported: As gender empowerment increased, the tendencies
decreased for women to place greater emphasis than men on a potential
spouse's earning capacity and for men to place greater emphasis than women
on a potential spouse's domestic skills. As expected in terms of the
gender-related development index's less direct representation of the
similarity of women's and men's roles, its correlations with these sex
differences were somewhat weaker.
As shown in Table 2, examination of the age differences preferred by men
and women in the 37 cultures showed that as gender equality increased,
women expressed less preference for older men, men expressed less
preference for younger women, and consequently the sex difference in the
preferred age of mates became smaller. These differences in age preferences
thus reflect a sex-typed division of labor, and they eroded substantially
as gender equality increased. Although the sex difference in age preference
did not completely disappear in societies with more equal gender roles, we
endorse Glenn's (1989) view that "the smaller mean size of the difference
in the samples from more developed societies suggests that it may
eventually disappear in some of them due to continued development" (p. 23).
Preference for physical attractiveness. As also shown in Table 1,
correlations between the sex difference in valuing potential mates'
physical attractiveness and the United Nations indexes of gender equality
were low and nonsignificant. Although these findings might seem to suggest
that the tendency for men to place greater value on partners' physical
attractiveness is a universal feature of mate selection, exceptions have
been reported (e.g., Walter,1997). Moreover, in traditional societies with
arranged marriages, physical attractiveness should not be very important in
mate selection because people are constrained to choose partners mainly on
the basis of factors such as tribal affiliation, family relationships,
social status, and wealth (Rosenblatt, 1974). Freedom of choice in mate
selection should increase the chances that physical attractiveness would be
relevant to mate selection. Consistent with this idea were the findings of
Rosenblatt and Cozby's (1972) cross-cultural study of 29 societies'
ethnographic records: Spouse selection for qualities such as beauty rather
than for skills, rank, alliances, and other tangible gains was positively
correlated with the freedom of choice that people had to select spouses
according to their own preferences. Because Buss's data were drawn
predominantly from cultures in which individual mate choice is likely to be
high, physical attractiveness of potential mates could play a role in mate
Although, at least in Western nations, physical attractiveness conveys
several kinds of meaning (e.g., dominance, good adjustment, intellectual
competence, and sexual warmth; Eagly, Ashmore, Makhijani, & Longo, 1991;
Feingold, 1992b), evolutionary psychologists have argued that one attribute
in particular is conveyed by women's physical attractiveness, and this is
reproductive capacity. In this view, women's attractiveness is determined
in large part by their possession of physical attributes suggestive of
youth (e.g., neonate facial features, small waist-to-hip ratios) and good
health, and these physical cues are indicators of fertility and
reproductive value (Buss, 1989; Jones, 1995; Singh, 1993). To the extent
that women's physical attractiveness, youth, and good health are indicators
of reproductive capacity within a society, then men's preference for
physically attractive partners plausibly should be linked to their preference
for young partners and their preference for healthy partners. The logic is
that the importance of these indicators of reproductive capacity is likely
to vary jointly in response to societal factors
that affect women's reproduction (e.g., the level of parasite infection,
Gangestad & Buss ). However, our analyses revealed little consistency
across the 37 cultures in such preferences. Across the cultures, men's
preference for physically attractive women was uncorrelated with their
preference for youthful women or healthy women in the ranking data,
although these factors were marginally correlated in the rating data (ps <
Within-culture data have similarly revealed inconsistent relations between
perceived attractiveness of women and their judged fertility (e.g.,
Cunningham, 1986; Tassinary & Hansen, 1998). Especially interesting is
Singh's (1993) research on the attractiveness of female figures that varied
in weight and waist-to-hip ratio. In multidimensional scaling analyses of
ratings of several features that might covary with these aspects of women's
appearance, perceived fertility clustered with depictions of women of
normal weight. Ratings of health, attractiveness, and sexiness formed an
independent group of perceptions that also clustered with figures of normal
weight. Perceptions of youth were relatively separate from these other
factors and clustered with depictions of underweight women.
Although little is known about the relation between women's attractiveness
and their actual fecundity, an exceptional study by Kalick, Zebrowitz,
Langlois, and Johnson (1998) found that facial attractiveness in early
adulthood was unrelated to number of children produced or to health across
the lifespan. Although the few participants in their sample who did not
marry were less attractive than those who did marry, once the nonmarried
were excluded, physical attractiveness was unrelated to the number of
children produced by male or female participants. Kalick et al. (1998)
concluded that "any relation between attractiveness and fecundity was due
to mate-selection chances rather than biological fertility" (p. 10). Of
course, as we noted in our critique of evolutionary psychology in this
article, hypothesized evolved dispositions, such as men's preference for
physically attractive partners, are not predicted to be related to current
reproductive success. Actual fertility and judgments of reproductive
capacity in modern societies may bear little relation to the factors
indicative of reproductive status in the EEA. Therefore, it is difficult to
know what kinds of data would validate the hypothesis that men's preference
for physically attractive mates in modern societies represents an evolved
disposition that arose during prehistoric times as a solution to the
problem of identifying fertile women.
In summary, several aspects of the findings from Buss et al.'s (1990) 37
cultures study are highly compatible with the social structural origin
theory of sex differences. The idea that the division of labor is a major
determinant of the criteria that people seek in mates fits with the
observed covariation between men seeking women who are younger and have
domestic skill and women seeking men who are older and have skill as
financial providers. The lessening of all of these tendencies with
increasing gender equality is consistent with the definition of structural
gender equality in terms of more equal participation by women and men in
wage labor and domestic labor. These sex differences in mate selection
criteria and in preferred spouse age are thus by-products of a social and
family structure in which the man acts as a provider and the woman acts as
a homemaker. More ambiguous are the sex differences in the emphasis on
mates' physical attractiveness. Our findings failed to support the
evolutionary argument that men's preference for attractive women is linked
to their preference for healthy, youthful women, which in turn are cues to
women's reproductive capacity. Although we believe that the sex difference
arises from the social implications of attractiveness in the societies in
Buss's sample, convincing evidence for either an evolutionary or a social
structural interpretation has yet to be generated. However, with respect to
the other sex differences emphasized by evolutionary psychologists, their
cross-cultural patterning suggests that they arise from a particular
economic and social system.
Within-society effects of social position. As evidence that presumably
counters the social structural interpretation of sex differences in mate
selection criteria, evolutionary psychologists (e.g., Buss & Schmitt, 1993)
have sometimes cited studies that have examined the relation within a given
culture between individuals' mate preferences and their economic resources
(e.g., Buss, 1989b; Kenrick & Keefe, 1992; Townsend, 1989). In one of the
most extensive of these studies, Wiederman and Allgeier (1992) assessed
mate preferences and anticipated income of undergraduate students from a
midwestern university and of Ohio residents. Mate preference ratings from
both samples yielded the typical sex differences in ratings of good looks
and good financial prospect. The central finding was that women's
anticipated income and their valuing of potential mates as good financial
prospect were weakly related or unrelated. That women with good financial
prospects still valued financial resources in their mates was taken as
evidence that social structural variables have little impact on women's
Wiederman and Allgeier's (1992) findings are uninformative in relation to
the social structural argument about mate selection because, as we noted in
our description of the social structural theory, societal gender roles
coexist with specific roles. Achieving a high paying occupation does not
necessarily neutralize the impact of broader gender role expectations.
Therefore, consistent with these broader norms, even women with
higher-than-average income commonly regard themselves as secondary
wage-earners in their marriages (Ferree, 1991) and prefer to leave the
labor force entirely or to become employed part-time while raising a family
(Herzog, Bachman, & Johnston, 1983; Tittle, 1981). Despite a substantial
income, women likely anticipate being partially dependent on their
husband's income, at least during a portion of their lifespan. Furthermore,
women who themselves have higher income would tend to come from higher
socio-economic groups and would anticipate selecting mates from their own
stratum of society. Homogamous mating on the basis of education,
occupation, and economic resources is a well established phenomenon (e.g.,
Kalmijn, 1991, 1994; Mare, 1991). Therefore, women's own income typically
should be positively related to their desired mates' financial prospects
(as found by Buss, 1989b). Although we are heartened by Wiederman and
Allgeier's (1992) attempts to test social structural hypotheses, future
within-culture analyses of mate preference should assess the influences of
specific role requirements (e.g., actual or anticipated marital roles) and
more diffuse role expectations (e.g., gender roles and expectations based
on social class and education). These points are equally applicable to
other questionnaire and interview studies of the relation between income
and the qualities preferred in mates (Buss, 1989; Townsend, 1989).
Considered at the level of a general metatheory of sex differences, social
structural theories provide alternative explanations of the great majority
of the general predictions about sex-differentiated social behavior that
have been featured in evolutionary psychology. Because the central
tendencies of sex differences (see Eagly, 1995; Halpern, 1997; Hyde, 1996)
are readily encompassed by both of these perspectives, neither the
evolutionary metatheory nor the social structural metatheory is
convincingly substantiated by a mere noting of the differences established
in the research literature. It is far too easy to make up sensible stories
about how these differences might be a product of sex-differentiated
evolved tendencies or the differing placement of women and men in the
social structure. This overlap in general main-effect predictions calls for
more refined testing of the two theoretical perspectives, and each
perspective is associated with a number of more detailed predictions and
Certainly there are many possibilities for distinguishing between the two
approaches with appropriate research designs (see Jackson, 1992).
Evolutionary psychologists have been especially resourceful in obtaining
cross-cultural data intended to support their claims of invariance across
cultures in sex-differentiated behavior. To be maximally informative about
social structural factors, cross-cultural research should be systematically
designed to represent cultures with differing forms of social organization
and levels of gender inequality (Miller-Loessi, 1995). In addition, a
variety of other research methodologies, including experimental studies and
field studies, can yield tests of predictions that emerge from evolutionary
and social structural perspectives.
Although this article contrasts social structural explanations of sex
differences with those based on evolutionary psychology, as we noted in the
introductory section, social structural analyses are generally compatible
with some evolutionary perspectives. Our argument that sex differences in
social attributes emerge from physical differences between the sexes in
conjunction with demands of the economy, features of the local environment,
and cultural beliefs is similar in spirit to dual-evolution theories that
emphasize coevolution by genetic and cultural processes (e.g., Barkow,
1989; Boyd & Richerson, 1985; Durham, 1991; see review by Janicki & Krebs,
1998). These models consider the interplay between genes, culture, and the
current environment. Although the various coevolutionary models differ in a
number of features (e.g., whether cultural change is directed to enhance
inclusive fitness), they share the assumption that culture evolves by
processes that are separate from but dependent on genetic evolution;
culture is influenced by and in turn helps to direct genetic structures.
The coevolutionary approach is consistent with the claims of some
evolutionary biologists and behavioral ecologists that behavioral
adaptations can be maintained from generation to generation through
nongenetic, presumably social mechanisms (e.g., Sork, 1997; Waage & Gowaty,
1997). Cultural change allows for the rapid spread of behavioral tendencies
within a generation and can facilitate the transmission of behaviors from
one generation to the next (Durham, 1991). Although we recognize the
importance of evolved genetic influences on the behavior of women and
men-in particular, influences stemming from men's greater size and strength
and women's reproductive activities-an implicit assumption of our approach
is that social change is not constrained to maximize individual society
members' inclusive fitness but instead is oriented to maximize the personal
benefits and minimize the personal costs of men and women in the social and
ecological settings in which they live. Although it is difficult to conduct
research that has clear implications for the multiple levels of analysis
inherent in dual inheritance models that integrate evolutionary and social
structural processes, this type of approach hold promise as a meta-theory
of psychological phenomena.
The definitive cross-cultural test of the evolutionary psychology and
social structural origin theories of sex differences may lie in the
future-that is, in the emerging post-industrial economies in which the
division between men's wage labor and women's domestic labor is breaking
down. Notable is the increase in women's paid employment, women's
increasing education, and the increase in women's access to many formerly
male-dominated occupations. Accompanying these changes is a marked
attitudinal shift toward greater endorsement of equal opportunity for women
in the workplace and role-sharing in the home (e.g., Sherman & Spence,
1997; Simon & Landis, 1989; Spence & Hahn, 1997; Twenge, 1997a).
Nonetheless, occupational sex segregation is still prevalent with women
concentrated in occupations that are thought to require feminine qualities
and men in occupations thought to require masculine qualities (e.g., Cejka
& Eagly, in press; Glick, 1991). Given that occupational segregation
currently takes this form, social structuralists would not predict that
either gender stereotypes or sex-differentiated behavior should have
already disappeared. Instead, it seems likely that, to the extent that the
traditional sexual division between wage labor and domestic labor erodes
and women and men become similarly distributed into paid occupations, men
and women will not only be perceived as similar but actually will become
more similar. In some psychological research literatures, this idea that
sex differences are disappearing is amenable to testing, at least over a
limited span of years, with meta-analytic techniques (e.g., Feingold, 1988;
Regardless of the status of scientific evidence on the convergence of the
sexes, perceivers believe that men and women are becoming more similar.
These beliefs have been demonstrated by Diekman and Eagly (1998), who
showed that people believe that women and men have converged in their
personality, cognitive, and physical characteristics during the past 50
years and will continue to converge during the next 50 years. Path analyses
suggested that perceivers function like implicit role theorists by assuming
that, because the roles of women and men have become more similar, their
attributes converge. The demise of most sex differences with increasing
gender equality, a proposition that thus fits popular beliefs about the
characteristics of women and men, is a social structural prediction that
will be more adequately tested as more societies produce conditions of
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Alice H. Eagly, Department of Psychology; Wendy Wood, Department of
Thanks are extended to David Buss for making available for reanalysis data
from his 37 cultures study (Buss, 1989b; Buss et al., 1990) and to Michael
Bailey, April Bleske, Galen Bodenhausen, David Buss, Lee Cronk, Amanda
Diekman, Martie Haselton, Dan McAdams, Radmilla Prislin, Eshkol Rafaeli,
Neal Roese, and Jeffrey Simpson for comments on a draft of the article.
Also, Crystal Toures provided assistance in locating and entering relevant
data, and Heather Franzese assisted with data entry.
Correspondence concerning this article should be addressed to Alice H.
Eagly, Department of Psychology, 2029 Sheridan Road, Northwestern
University, Evanston, IL 60208, or to Wendy Wood, Department of Psychology,
Texas A&M University, College Station, TX 77843. Electronic mail may be
sent via Internet to email@example.com or firstname.lastname@example.org.
Correlations of Mean Rankings and Ratings of Mate Selection Criteria With
Indexes of Gender Equality for the 37 Cultures Sample
Mate selection criterion
Gender empowerment measure
(n = 33)
Gender-related development index
(n = 34)
Gender empowerment measure
(n = 35)
Gender-related development index
(n = 36)
Good earning capacity (financial prospect)
Good housekeeper (and cook)
Physically attractive (good looks)
Note. Higher values of United Nations indexes indicate greater gender
empowerment and gender-related development. Higher mean rankings and
ratings of mate selection criteria indicate greater desirability in a mate.
The attributes were described slightly differently in the ranked and rated
data; the attributes in parentheses are from the ratings. Sex differences
in mate selection criteria were calculated as female minus male rankings
for good earning capacity and male minus female rankings for good
housekeeper and physically attractive. For sex differences, a positive
correlation thus indicates an increase in the sex difference as the
relevant United Nations index increases, and a negative correlation
indicates a decrease in the sex difference. For the reports of women or
men, a positive correlation indicates an increase in the desirability of a
criterion as the relevant United Nations index increases, and a negative
correlation indicates a decrease.
? p < .10. * p < .05. ** p < .01. *** p < .001.
Correlations of Mean Ratings of Preferred Age Difference Between Self and
With United Nations Indexes of Gender Equality for the 37 Cultures Sample
Gender empowerment measure
(n = 35)
Gender-related development index
(n = 36)
Note. Higher values of United Nations indexes indicate greater gender
empowerment and gender-related development. Positive ages indicate
preference for older spouse, and negative age indicates preference for
younger spouse. Because the sex difference in preferred age was calculated
as female minus male preferred age, a negative correlation thus indicates a
decrease in the sex difference in preferred age as the relevant United
Nations index increases. For the ratings by women, a negative correlation
indicates a decrease in the tendency to prefer an older spouse as the
relevant United Nations index increases, whereas for the ratings by men, a
positive correlation indicates a decrease in the tendency to prefer a
*** p < .001.