Humans: Nature and Nurture
We have spent the last three chapters examining sexually dimorphic animal behavior. The theory and data regarding the different reproductive strategies of female and male animals is generally well accepted in biology and ethology (the study of animal behavior). However, when a similar approach is applied to the study of human sex and gender differences, the topic has been hotly controversial in the social sciences, the humanities, and in political and social discourse.
In this chapter we will explore the history and current status of the "nature vs. nurture" controversy, review the set of predicted robust human sex differences derived from evolutionary theory, and explore some of the research methods that are used by evolutionary psychologists.
The nature-nurture controversy has a long history, with the pendulum of scientific and popular opinion swaying to and fro -- generally more as a result of intellectual fashion than on the basis of conclusive scientific evidence. On the nurture side have been the "biological determinists" who argued that biological causality is a far more important determinant of human behavior than social or cultural causality. For example, the famous statistician Karl Pearson argued in his 1910 book, "Nature and Nurture: The Problem of the Future," that the influence of the environment is "not one fifth that of heredity, and quite possibly not one tenth of it" (in Freeman, 1983, p. 17). The "cultural determinists" asserted the opposite viewpoint. Franz Boas, an anthropologist and a proponent of this perspective in the early 1900s, argued that culture "is not an expression of innate mental qualities;" rather it is "a result of varied external conditions..." His intellectual goal was "...to focus attention on cultural process, to free the concept of culture from its heritage of evolutionary... assumptions, so that is could subsequently become... completely independent of biological determinism" (quotes in Freeman, 1983).
A middle ground in this controversy is "interactionism" -- the perspective that behavior is caused by a complex interaction of both nature and nurture. The various theoretical positions can be summarized, as below, according to the relative weight given to biological or cultural influences.
Social / Cultural Causality
Both biological and cultural determinism are false.
All behavior is a result of a complex interaction, or "co-mingling," of biological and environmental factors. With a little thought it is easy to see that it could not be otherwise. Although it is possible to statistically partition the differences between people to either genetic or environmental factors (using the "heritability index" -- a term which we shall discuss later), no behavior is caused exclusively by nature or nurture. Unfortunately, interactionism has not been, and, to a large extent is still not, fully appreciated in the social sciences. The sterile "nature vs. nurture" controversy has wasted intellectual energy for more than a century. The ramifications of this debate have also spilled out of academia. Some political philosophers and activists have embraced either extreme and then used their preferred paradigm in an attempt to "validate" certain political philosophies (Wilson, 1998).
Despite the fact that "nature vs. nurture" is a false dichotomy, strangely, the debates continue to this day in the social sciences, especially in sex and gender studies. The "nurture" perspective has been dominant in academia for most of the 20th century, and it remains highly influential. It will be useful for us to review the history of this debate to appreciate the controversy, and to understand current perspectives related to sex and gender differences.
"The poverty of the incapable, the distresses that come upon the imprudent, the starvation of the idle... which leave so many 'in shallows and in miseries,' are the decrees of a large, farseeing benevolence."
-- Herbert Spencer (quote in Wright, 1994, p. 330).
As you learned in Chapter 1, the naturalistic fallacy (the assumption that "what is natural is good") is generally an invalid derivation from evolutionary theory. When political philosophies have relied on this fallacy to justify social policy, history suggests that potentially dangerous politics can result. This was the case with two political movements in the late 1800s: social Darwinism and eugenics.
Social Darwinism, a political philosophy spearheaded by Herbert Spencer, was predicated on the naturalistic fallacy, as well as a second erroneous presumption: the idea that evolution "progresses" toward better, or "higher," forms (it does not, necessarily). These twin misunderstandings of biological evolution led social Darwinists to infer that advances in civilization are dependent on "the survival of the fittest." To interfere with this "natural" process would inhibit social achievements. In this view, social policy should allow the poor, the chronically ill, and the physically or mentally weak, to die or fail unaided by society -- this would contribute, in the long run, to the betterment of society.
A related political philosophy, eugenics, also confused what "is" and what "ought." The term was coined in 1883 by a cousin of Charles Darwin, Sir Francis Galton. His idea was to use artificial selection to improve the human species by selective breeding. This included proposals for the forced sterilization of "genetically inferior" individuals -- including those of lesser intelligence or with other genetically predisposed disabilities. By so doing, society could eventually breed a superior "race" of humans. Galton wrote that in 1873 that society should accept as its "paramount duty, to anticipate the slow and stubborn processes of natural selection, by endeavoring to breed out feeble constitutions and petty and ignoble instincts, and to breed in those which are vigorous and noble and social" (quote in Freeman, 1983, p. 10). Assuming everyone could agree on the definition "vigorous, noble and social," in principle eugenics was (and is) possible. However, most people today would see such tampering as an intolerable government intrusion and a violation of individual rights. The naturalistic fallacy, as well as other inappropriate political derivations of evolutionary theory, have been used as justifications for other harmful political agendas, including imperialism, racism, sexism, colonialism and, most egregiously, for the Nazi holocaust during World War II.
A political reaction against social Darwinism and eugenics began in the early 1900s. Unfortunately, it failed to focus on the real problem: the uncritical acceptance of the naturalistic fallacy and the erroneous idea that evolution necessarily produces "progress." A different tactic was used: if it could be determined that behavior was caused by social, as opposed to biological factors, then the naturalistic fallacy would be made irrelevant. That is, if behavior is not "natural" (not caused by human nature), but purely socially constructed, then there could be no suggestion that such "natural" behavior was "good." Thus, biologically-based political justifications for discrimination, imperialism, social Darwinism, eugenics and sexism would be rendered impotent. Using this tactic to counter the biological determinists (instead of focusing on countering the naturalistic fallacy), between 1910 and 1930 the cultural determinists re-ignited the nature-nurture controversy. One observer wrote in 1924 that "No subject of sociological inquiry within recent years has proved to be more controversial than the effort to determine the relative importance of biological and of purely social factors in the development of human society" (Rice, 1924; quoted in Freeman, 1983, p. 3 - 4).
By the 1930s a winner in this social sciences debate had emerged: cultural determinism prevailed over biological determinism (Degler, 1991). This was accomplished without scientific evidence to prove that biology did not influence behavior; instead it was due to a backlash against unsavory political theories. The consensus gradually emerged in the social sciences that all biological explanations, including evolutionary and genetic ones, were to be excluded from an analysis of human behavior. Social scientists began to avoid and denounce attempts to explain behavior using any reference to biological causality (Degler, 1991).
In psychology, an important proponent of the "nurture" position in the 1920s was the founder of behaviorism, John B. Watson. He wrote the passage for which he is most famous in 1924:
Give me a dozen healthy infants, well formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select D- doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors. I am going beyond my facts and I admit it, but so have the advocates of the contrary and they have been doing it for many thousands of years. Please note that when this experiment is made I am to be allowed to specify the way the children are to be brought up and the type of world they have to live in. (p. 104)
While behaviorism grew in psychology, "cultural materialism" was gaining rapid acceptance in cultural anthropology. Of particular influence were the writings of perhaps the most famous anthropologist who has ever lived: Margaret Mead. The outcome of the nature vs. nurture debate in early 20th century anthropology would come from an unlikely place: two remote islands in the South Pacific: American Samoa and New Guinea.
Margaret Mead was in graduate school during the height of the nature vs. nurture debate. Her primary doctoral professor was Franz Boas. His goal was to establish cultural anthropology as a discipline completely independent of biology. However, to support this position, Boas needed to gather empirical data. He recruited his graduate student, the 23 year old Margaret Mead, to assist him. Together Boas and Mead decided that she would study the natives of American Samoa, an isolated island in Polynesia. The question to be investigated was the extent to which adolescent rebellion and emotional turmoil (a particular concern at the time in American culture) was also evident in adolescent Samoan girls. If it was not, then such a "negative instance" could be used to counter the biological determinist notion that adolescent rebellion is biologically influenced (since it would demonstrate that adolescent turmoil is not a cross-cultural human universal).
When Mead arrived in Samoa 1925, the daughter of the Samoan chief, Fa'amotu, was assigned to be Mead's constant companion. After a nine-month stay studying Samoan culture, during which time she interviewed several adolescent Samoan girls, Mead returned to New York and wrote Coming of Age in Samoa, a book that detailed her Samoan observations. She described the Samoans as having a culture completely free of adolescent difficulties, and, moreover, "replete with easy solutions for all conflicts." For Boas, and the cultural determinists, this was a significant finding. As noted by Mead, "in anthropology you only have to show once that it is possible for a culture to make, say, a period of life easy, where it is hard everywhere else, to have made your point" (Freeman, 1983, p. 77). The "point" was that biology had nothing to do with adolescent rebellion. The only remaining possible causal factor was, of course, culture.
In her conversations with the Samoan adolescent girls, Mead found other striking exceptions to typical Western behavior. The Samoan adolescent girls, she reported, practiced promiscuous sex. A Samoan girl would distribute her sexual favors indiscriminately among many males. According to Mead, the goal of Samoan adolescent girls was to enjoy "many years of casual lovemaking" with many different lovers, while attempting to postpone marriage for as long as possible. Mead described Samoan male adolescents as skillful lovers who's sexual aggressiveness never had to be curbed and "the idea of forceful rape... is completely foreign to the Samoan mind" (quote in Freeman, 1983, p. 93). Mead wrote that, among Samoans, neither males nor females experienced sexual jealousy, or became possessive of their lovers.
Perhaps because of these astonishing findings, Coming of Age in Samoa became a popular best seller. The Samoans' sexual "free love" and their freedom from jealousy, possessiveness, rape, and adolescent turmoil, seemed as alien to Western culture as if the Samoans had come from another planet. For many social scientists, it provided the empirical "proof" they needed to verify cultural determinism. (This was at a time before the philosopher Karl Popper had published his ideas, now generally accepted, that theories are never "proven" in science, but only "corroborated" after surviving many rigorous empirical attempts to falsify them).
Coming of Age in Samoa was used as a textbook for American college undergraduates as a definitive example of the extreme malleability of human nature, as well as the completely arbitrary nature of sex roles. Any claims about the biological influences on behavior, or the suggestion of the existence of underlying universal sex differences, could be easily dismissed with a simple question: "But, what about Samoa?" (Wright, 1994).
Cultural anthropology's research program to support cultural determinism by discovering "negative instances" to putative human universals in various cultures had just begun. To offer further evidence of the malleability of sex roles, in her next book, Sex and Temperament in Three Primitive Societies (1935), Mead reported that she had discovered highly variable sex roles in three tribes in New Guinea:
Here, admittedly looking for light on the subject of sex differences, I found three tribes all conveniently within a hundred mile area. In one, both men and women act as we expect women to act--in a mild parental responsive way; in the second, both act as we expect men to act--in a fierce initiating fashion; and in the third, the men act according to our stereotype for women -- are catty, wear curls and go shopping, while the women are energetic, managerial, unadorned partners (from the preface to the 1950 edition)....These three situations suggest, then, a very definite conclusion. ...we no longer have any basis for regarding such aspects of behavior as sex-linked. (p. 279 - 280)
The gender roles that Mead discovered in each of these societies (the feminine Arapesh society, the masculine Mundugumor society and the sex-role reversed Tchambuli society) can be neatly summarized in the following table:
America, circa 1950s
What implications could be drawn from Mead's discovery? Mead concluded that "Many, if not all, of the personality traits which we have called the masculine or feminine are as lightly linked to sex as are the clothing, the manners, and the form of head-dress that a society at any given time assigns to either sex... the evidence is overwhelming in favor of the strength of social conditioning" (quote in Doyle & Paludi, 1998, p. 93). And the conclusion drawn by many social scientists was similar: there are no biologically mediated behavioral sex differences; the sexes are different in morphology only.
From a political perspective, it is perhaps understandable why these findings were embraced uncritically. If socialization caused sex differences, then, by implication, gender inequalities must be due to socialization as well. Presumably, socialization practices are more easily changed than "intractable" biologically mediated based sex differences. This was good news, politically, because it implied that gender inequalities could be eliminated simply by changing socialization practices. To achieve equality between the sexes, society need not work against ingrained biological predispositions. Nor must society dismantle the erroneous "but its only natural" argument from those who mistakenly assume that what is "natural" must therefore be "good." Not surprisingly, Mead's findings were highly praised and uncritically accepted in the social sciences, in feminist theory, in the humanities, and in popular culture. The older phrase that "Human nature, being what it is…" was replaced with "In our culture, ..." -- and whatever phenomenon that followed this sentence stem was implicitly culturally caused, since things could be so radically different in other cultures.
Although Mead's motives for searching to find cross-cultural variability in sex roles may have been well intentioned, for a certain set of "robust" sex differences there is not as much cross-cultural variability in sex roles as Mead might have imagined (e.g., Brown, DATE, Buss, 1989). There has never existed a culture wherein women, more than men, are more frequently the physical combatants in warfare; where women compete intrasexually more intensely for sexual access to the opposite sex; where men are viewed as "reproductive property" by women and are thus jealously sequestered and guarded; where women are generally more sexually interested in the prospect of casual copulation with a long string of novel sexual partners, where women war parties raid other villages to capture men to stock their harems with husbands; where men invest more time and effort raising young children than do women; where women are more concerned about their partner's chastity or virginity. None of the above sex role reversals (referring to group averages, rather than individual differences) have been consistently observed in any culture, including the ones that Mead studied on Samoa and New Guinea.
For the Somoans, this was made clear in 1983 by the anthropologist Derek Freeman. In his book Margaret Mead and Samoa: The Making and Unmaking of an Anthropological Myth Freeman (1983) presented evidence from his own, and others', observations of the Samoans that -- far from being a haven for adolescent free love, and devoid of sexual jealousy and rape -- the Samoans had a sexually restrictive and protective culture, a cult of virginity, and a rape rate 2.5 times that of the United States. For example, Freeman found that boys who were suspected of having sexual intentions toward a girl were sometimes physically assaulted by the girl's relatives. The girl herself was often castigated or assaulted by her own relatives if she was found with the boy. In Coming of Age in Samoa Mead made the curious statement that "A girl's promiscuity seems to ensure her against pregnancy" . Although Mead documented her informants' fertility (their menstrual cycle), surprisingly none of these sexually active girls got pregnant. Mead did not elaborate on the unexpected inverse relationship promiscuity and pregnancy in a culture that practiced birth control by "violent massage and the chewing of kava" (Mead, 1928, p. 153).
Virgin brides were so valued in Samoa that a public test of their virginity was celebrated on the brides’ wedding day. With two fingers, the groom would publicly rupture his naked bride's hymen, and then hold his bloodied fingers up high for all the assembled to see. Below are the lyrics of a Samoan song sung during a marriage ceremony to celebrate the bride's virginity (Freeman, 1983, p. 232):
The way into the vagina...
The sacred fluid gushes forth...
All others have failed to achieve entry...
He is first by being foremost...
O to be foremost!
If the groom was not "foremost" – should no blood appear on his fingers -- the wedding festivities came to an abrupt halt. The bride was called the equivalent of a "whore," gifts were taken back, the marriage cancelled, and, in some cases, the bride was brutally beaten with clubs, sometimes fatally. This is hardly the peaceful, idyllic society that Mead had portrayed.
Despite the inaccuracy of some of Mead's conclusions in Coming of Age in Samoa, it is unlikely that her accounts of Samoan culture were intentional distortions (for a review of the controversy, see Caton, 1990). She fervently believed and promoted cultural determinism, and she had a pre-conceived notion of the South Seas as romantic, earthly paradise. Mead was also inexperienced. She was only 23, and Samoa was her first anthropological field trip. When she arrived in Samoa, she had only a ten-week introduction to the Samoan language. She choose not to live full time in a Samoan village; instead, she lived with American expatriates who ran a Naval medical dispensary. For her anthropological data, Mead relied largely on the scheduled interviews at the dispensary with her adolescent girl informants.
She did not check to verify the statements of her informants with boys, adults, or with Samoan educational or cultural authorities.
Freeman (1983) reported that all other ethnographers that had studied the Samoans indicated that they (especially the adolescent girls), were very reluctant to discuss sexual matters, particularly with an outsider. Freeman (1983, p. 290) concluded that when Mead "persisted in this unprecedented probing of a highly embarrassing topic, it is likely that these girls resorted... to regaling their inquisitor with counterfeit tales of casual love... "
The controversy about Samoan culture was presented the 1988 documentary film by Frank Heimans "Margaret Mead and Samoa" (Heimans, 1988). Below are a few excerpts from several people who were interviewed in the documentary.
Samoan High Chief A. P. Lutali:
I went to the University of Hawaii in 1948. ... it was during an anthropology class that I realized that something was being taught that was not in accordance with our (Samoan) way of life and culture. And during this anthropology class I got up and objected to professor Mason, who was the instructor. I got up and I told him that I do not, and did not believe at that time, to what Margaret Mead was saying in her book about the sex life of the Samoan young people. And he said to me, "How do you know?" And I said, "Well, I should know. I grew up in that culture. I am of the age Margaret Mead is writing about. And that is not true."
Tim O'Meara, anthropologist:
One of the main forms of entertainment in a Samoan village is what I call recreational lying... it is the old pulling people's legs... People tell you stories to get you to believe it. My (Samoan) friends used to do this to me all the time. And often it's about sexual matters....
Samoan Talking Chief Toeaina Muasau:
Margaret Mead was here in 1926... I usually helped her with carrying her mosquito net, typewriters, and some folders for her work. ...I think some girl told her a wrong story. The Samoan people, you know, if they want a laugh (at the expense of) a foreigner... so they told her the wrong story, to influence her to listen to the story, but it was not a true story.
One of Mead's original informants, Fa'apua'a Fa'amu:
I remember her (Margaret Mead) very well... we were like sisters... she asked us what we did after dark. We girls would pinch each other and tell her we were out with the boys. We were only joking but she took it seriously. ...Samoan girls are terrific liars ...we just lied and lied.
Dr. Franaafi Le Tagoloa, Professor of Samoan Studies:
Margaret Mead took away our, perhaps not our humanity so much, as our oneness with other human beings. ...we are no different from you... or (people in) any other place in the world. ...Perhaps it's our cultures that make the semblence of difference.
As noted earlier, Mead's subsequent book, "Sex and Temperament in Three Primitive Societies," managed to neatly fill in the three remaining possible sex-role quadrants with three New Guinea tribes all located "conveniently within a hundred mile area." Like her Samoan work, Mead's methods and conclusions in New Guinea have been criticized as seriously flawed (see review in Daly & Wilson, 1988). Although Mead described both Arapesh males and females as "feminine," her own reports, as well as those of other ethnographers, detail exclusively male warfare and deadly battles over women. Ironically, Mead's own husband published an article titled "Arapesh Warfare" which contradicted Mead's claims about the "gentle" Arapesh (Fortune, 1939). Tuzin (1977, 1980) reported that a young Arapesh male kill an enemy before he was allowed initiation into manhood (females were under no such obligation). Mead described both Mundugumor males and females as "masculine." However, only the males engaged in polygamy and murderously raided other villages to acquire additional wives. The Mundugmor, like the Arapesh, believed that only by killing an enemy could a male achieve fully adult status. Mundugmor women, in contrast, did not raid other villages for husbands and managed to achieve adult status without murderous violence. Among the presumably "sex-role reversed" Tchambuli (now called the Chambri), the males wore make-up which Mead apparently found to be feminine. However, the make-up was more akin to war paint -- they wore it to celebrate the first time a young male had killed an enemy! The victim's heads were hung in the ceremonial house as a trophy. Ethnographers report that the Tchambuli have a long history of warfare, and have exterminated entire villages (Gewertz, 1983).
As suggested by Daly and Wilson (1988), Mead's conclusions in "Sex and Temperament in Three Primitive Societies" were a tad bit too tidy:
The dark forces of sexism and ethnocentrism would have us believe that aggressive-male/passive-female constituted the only possible combination. Suddenly, Mead had demolished that claim by filling in the other threecells of the matrix at a single stroke! What could be neater? (p. 150)
Although Mead suggested that in this presumably sex-role reversed society women were dominant over men, Mead wrote that "and yet the men are after all stronger, and a man can beat his wife, and this possibility serves to confuse the whole issue of female dominance ." By 1973, Mead had apparently abandoned her claim about the sex-role reversed Tchambuli: "It is true... that all the claims so glibly made about societies ruled by women are nonsense. We have no reason to believe that they ever existed..." (quote in Goldberg, 1993, p. 35). In 1974 - 75 the Tchambuli were studied by another anthropologist (Gewertz, 1981). She did not find a sex role reversal in aggressiveness; further, she noted that the political arena was virtually closed to women, and women were expected to hand over the proceeds of their fishing expeditions to their husbands or fathers, who used them to increase their own status.
One commentator remarked that it is the "professional malpractice anthropologists to exaggerate the exotic character of other cultures" (Bloch, 1977, p. 285), and by so doing, overlook the underlying commonalties. Like tourists visiting a distant country, what catches the eye of many cultural anthropologists are cultural differences. As we mentioned in Chapter 1, although languages can be very different in various cultures, all people share the universal human nature that predisposes young children to learn a language almost effortlessly. It can be easy to overlook the underlying commonalties, or the "human nature," beneath some superficial cultural differences.
Sex role reversed
Only males are warriors, and are allowed to paint their faces (which Mead considered "make-up",
Both males and females are
A young Arapesh male must commit a homicide in order to be initiated into manhood.
Both men and women are violent and aggressive.
Men, but not women, raided other villages for heads and wives. All males, but not females, were obliged to kill an enemy before achieving
Although both Mead’s research methods, and her conclusions, are no longer considered valid by most anthropologists, in adjacent social sciences (e.g., sociology, psychology, gender studies, sexuality studies, feminist theory) Mead's reports are still cited uncritically to support cultural determinism. Minderhout (1986) found that in 61 psychology and 51 sociology textbooks, Mead was the most frequently cited anthropologist, and that Sex and Temperament in Three Primitive Societies was her most frequently cited work. In several textbooks, Mead's works are still cited to support the conclusion that sex roles are arbitrary and socially constructed (see the box for some examples). Ironically, although it is largely ignored, in later life Mead herself questioned whether cultural determinism was sufficient to explain persistent, cross-cultural sex differences. Mead wrote in the introduction of the 1962 edition of Male and Female: “...I would, if I were writing it today, lay more emphasis on man's specific biological inheritance from earlier human forms and also on parallels between Homo sapiens and other... species." To her credit, Mead apparently was willing to revise her views as more scientific evidence became available (Townsend, 1998).
Margaret Mead's conclusion that sex roles are arbitrary and purely socially constructed is still presented uncritically in several recent psychology, human sexuality, and gender differences textbooks.
From Sexuality in a World of Diversity (Nevid, Fichner-Rathus, & Rathus, 1995):
In Sex and Temperament in Three Primitive Societies (1935), Mead laid the ground-work for recent psychological and sociological research challenging gender-role stereotypes. ...Mead concluded that these stereotypes are not inherent in our genetic heritage. Rather, they are acquired through cultural expectations and socialization. That is, men and women learn to behave in ways that are expected of them in their particular culture. (p. 25)
From "Our Sexuality" (Crooks & Baur, 1990):
In several societies, the differences between males and females that we often assume to be innate are simply not evident. In fact, Margaret Mead's classic book Sex and Temperament in Three Primitive Societies (1935) reveals that other societies may have very different views about what is considered feminine or masculine. ...Because there is no evidence that people in these societies are biologically different from Americans, their often diametrically different interpretations of what is masculine and what is feminine seem to result from different processes of social learning. (p. 74)
From Human Sexuality Today (King, 1996):
...completely opposite gender roles can be found in cultures living in close proximity to one another. Margaret Mead (1935, 1975), for example, described a tribe in New Guinea... (p. 204)
From Foundations of Contemporary Psychology (Schlenker & Severy, 1979):
Margaret Mead (1949) in her classic work... describes various New Guinea cultures wherein it is the female who is responsible, makes all the decisions, and is aggressive -- with the males being docile, submissive, and homebodies.
From Essentials of Psychology (Rathus, 1997):
The experiences of anthropologist Margaret Mead (1935) on the South Pacific island of New Guinea showed how the sociocultural milieu influences motives such as aggressiveness and nurturance. Among the Mundugumor... (p. 410).
From Sex and Gender, An Introduction (Lips, 1997):
In the realm of sex and gender, the pioneer of cross-cultural research was anthropologist Margaret Mead (1935), who's research in New Guinea demonstrated that cultures could and did differ dramatically in their notions of masculinity and femininity. ...Her book contrasted the Arapesh.... (p. 88)
From Sex and Gender: The Human Experience (Doyle & Paludi, 1998):
During the early 1930s, Margaret Mead set off to explore the ways that gender roles were defined among several preliterate societies in northeastern New Guinea. There Mead found the material for what was to become the basis for the now classic study of gender roles entitled Sex and Temperament in Three Primitive Societies (1935/1963). Each of the three societies that Mead studied -- the Arapesh, the Mundugumor, and the Tchambuli -- had very different conceptions of what was expected of women and men. ...(Mead's results suggest that) culture is an important -- if not the sole -- factor in shaping one's gender presentation." (p. 97,98)
From A World Full of Women (Ward, 1996, p. 30, 38, 49):
Many of us who teach gender turn to this book (Sex and Temperament in Three Primitive Societies). It informs, provokes, and illustrates. ...these small, intact cultures seemed to play with elaborate permutations of being male or female. ...These three groups showed Mead that a culture may impose personalities and patterns on one gender or both genders that are only a subset of the whole spectrum of possibilities available to human beings. ...We see that gender roles are not fixed, rigid, or defined for all time. Sex roles are not divinely assigned nor inherent in something we call "nature."
From Questions of Gender: Perspectives and Paradoxes (Anselmi & Law, 1998):
It is questionable whether the concept of human nature means anything... (based on the work of Margaret Mead) (Hubbard, 1998, p. 151).
Especially with respect to sex differences, most social scientists for the past century have been acutely "biophobic." Any biological and evolutionary analysis of behavioral sex differences have been labeled "biological determinism," "sexist" or "reductionistic." Daly and Wilson (1988) wrote that "It is our conviction that the biophobia that is rampant in the social sciences is founded more in ignorance than in a reasoned critique of evolutionary theory ."
Intellectual disagreements in academia generally do not result in fisticuffs, however, when evolutionary analyses of behavior began to re-emerge after the 1975 publication of E.O. Wilson's book Sociobiology, the academic climate, at times, became more hotly political than coolly scientific. A letter highly critical of Wilson's book was published in the November, 1975 issue of the New York Review of Books. It had sixteen signatories, including two of Wilson's colleagues at Harvard, Stephen Gould and Richard Lewontin. The letter claimed that sociobiological theories "provide a genetic justification of the status quo and of existing privileges for certain groups according to class, race, or sex... (such groups) have drawn support from... these products of the scientific community... (and) provided an important basis for the enactment of sterilization laws and restrictive immigration laws by the United States between 1910 and 1930, and also for the eugenics policies which led to the establishment of gas chambers in Nazi Germany" (noted in Fisher, 1992, p. 74). A pitcher of water was dumped on Wilson at a scientific conference by members of a leftist group called "Science for the People." In their book "Not in Our Genes" Lewontin, Rose and Kamin (1984) mis-quoted a passage from Richard Dawkins' (1976) book "The Selfish Gene." Dawkins had written that genes "...created us, body and mind"; these authors changed "created" to "control" in this passage. Their misquote attributed a vastly different meaning than the one intended by Dawkins. When the cultural anthropologist Napoleon Chagnon (1988) reported that 25 percent of all Yanomamo Indian males are murdered or killed in tribal warfare, his work was denounced by colleagues who found it was at odds with polyannish views of "primitive" people living in harmony with nature and each other.
When the respected journal Scientific American published an article critical of behavioral genetics, it was titled "Eugenics Revisited" (Horgan, 1993). Another article in Scientific American, critical of evolutionary psychology, was titled "The New Social Darwinists" (Horgan, 1995). Evolutionary researchers viewed such titles as slurs and mis-characterizations their discipline by associating them with old and discredited political movements that had nothing to do their own personal philosophies, or their work (Pinker, 1997).
After Freeman's (1983) refutation of Mead's Samoan work was published the American Anthropological Association voted to denounce his findings as unscientific at its annual meeting in 1983. Freeman (in Heimans, 1988) commented that:
This is a quite extraordinary event because the scientific truth is something that cannot be settled politically -- it's something that depends on the evidence. And I realized when this news reached me that in fact my refutation had been a great success because it had prompted these people into this quite extraordinary reaction.
Voting on the scientific truth was not limited to this one instance. There is a consistent sex difference in physical aggression -- males are far more likely the engage in these behaviors than are females -- and this is true in most species, including humans. This suggests that aggression is a sex-linked trait and thus biologically influenced. At a 1986 meeting titled "Brain and Aggression" twenty social scientists drafted "The Seville Statement on Violence." It was subsequently printed twice in the journal American Psychologist (Seville Statement, 1990; Scott & Ginsburg, 1994). The statement was designed to "challenge a number of alleged biological findings that have been used... to justify violence and war." The Seville Statement concluded that "it is scientifically incorrect to say that we have inherited a tendency to make war from our animal ancestors... that other violent behavior is genetically programmed into our human nature... that in the course of human evolution there has been a selection for aggressive behavior... " What are the causes of war, then? The Seville Statement concluded that warfare is purely "a product of culture."
Several international scientific societies officially endorsed the Seville Statement's conclusions about what is "scientifically incorrect," including American Anthropological Association, the American Psychological Association, the American Orthopsychiatric Association, and the American Sociological Association. As noted by Freeman earlier, this is surprising, because, again, what is "scientifically correct" cannot be determined by vote or official proclamation -- it is dependent on the results of many independent empirical investigations. Fox (1988, p. 4) suggested that the Seville Statement was a "shop worn denunciation of ideas" that misrepresented the views of evolutionary biologists.
Of such biophobia Pinker (1997, p. 46) asked "What moral certainty could have incited these scholars to doctor quotations, censor ideas, attack the ideas' proponents ad hominem, smear them with unwarranted associations to repugnant political movements, and mobilize powerful institutions to legislate what is (scientifically) correct and incorrect?" He suggested that such over-reactions were due to several misunderstandings, including some of those noted in the following table.
Concerns about misunderstandings by laypersons and politicians about biological influences on behavior, and some potential solutions to these misunderstandings.
Naive acceptance of the naturalistic fallacy.
Identify and dismantle the false idea that what is "natural" is necessarily "good."
Erroneous belief that natural selection always produces biological and social progress.
An understanding that evolution is blind to any future goals, and does not necessarily result in "progress."
Unrealistic belief that social attempts to modify negative behaviors will be futile if behavior is biologically influenced.
An appreciation that an understanding of biological causality may be used to make social interventions more effective.
Unwarranted expectation that individuals may not be held accountable for their behavior if that behavior is determined to be biologically influenced.
If behavior is "caused," it is irrelevant if the causes are social or biological. Understanding the causation of behavior may help develop interventions to prevent or change undesirable behaviors.
Concern that within-sex variability will be ignored or minimized when average sex differences are reported. Social policy might be based on average group sex differences.
Individuals should be assessed and appreciated as individuals – not conceptualized as a miniature model of of a group. Virtually the entire range of temperaments and abilities is expressed in the variability between individuals within each sex.
Today, most evolutionary researchers believe that no moral or political philosophy can be derived from the operation of natural phenomena. We wouldn't expect geology, chemistry or astronomy to provide us with answers to moral questions; neither should we expect to find moral guidance in the operation of evolutionary processes. Eventually, evolutionary psychology may help us understand why we have evolved a sense of ethics and morality, but it cannot tell us what the content of moral systems should be (Barash, 1982). Because biologically based theories of behavior have been misunderstood and misused for political purposes, they have often been pigeonholed as potential tools for right-wing or "anti-progressive" politics (e.g., see Fausto-Sterling, 1985; Lips, 1997). But cultural determinism, too, has had its share of political misappropriations. It has served as the philosophical foundation for some nefarious left-wing political platforms (Pinker, 1997). The idea that humans are born an empty "tabula raza” and that, throughout life, behavior is easily pliable and purely socially constructed, was used as a justification for Marxism, communist dictatorships, the "re-education" camps in the killing fields of the Khmer Rouge in the 1970s, the Stalinist purges, the failed communes and group marriages of the 1960s flower children, the early attempts by Israeli kibbutzim to socially engineer relations between the sexes, (and between mothers and
their children), etc. Although Marxist and leftist ideas of behavioral equipotentiality have led to genocide and repession, the supporting SSSM theories were left largely untarnished by such distasteful associations (Turner, Mulder, Cosmides, Giesen, Hodgson, Maryanski, Shennan, Tooby and Velichkovsky, 1997) Margaret Mead (1935, p. 310) suggested that "The knowledge that the personalities of the two sexes are socially produced is congenial to every programme that looks forward towards a planned order of society. It makes possible a Communist programme in which the two sexes are treated as nearly alike as their different physiological functions permit."
An over-emphasis on purely cultural causality has led some to see medical complaints, including menstrual cramps, pregnancy sickness and childbirth pain, as manifestations of purely cultural factors. Cultural determinists tended to blame mothers for their children's' schizophrenia, autism, homosexuality, and anti-social behavior -- disorders for which there is now evidence are biologically predisposed (ref). Adults suffering from psychological dysfunctions, including depression, anxiety, sexual dysfunction, obesity, etc., were thought by cultural determinists to simply have been subject to inappropriate social conditioning. Behavior modification, psychotherapy, or psychoanalysis were often hyped as easy cures for such defective learning. However, the results of psychotherapy were not often robust, and with many "problems of living" these interventions were not much more effective than a placebo, talking to a friend or a para-professional, or the simple passage of time (for a review see Dawes, 1994).
In conclusion, the goal of the psychological and social sciences is to as objectively as possible investigate the causes of behavior. The scientific validity a behavioral theory should not hinge on whether it has been misused for political purposes (by either the political left or right). Pinker (1997, p. 48) appropriately suggested that we should "expose whatever ends are harmful and whatever ideas are false, and not confuse the two."
With cultural determinism serving as its intellectual paradigm during the 20th century, the social sciences developed under a certain set of explicit and implicit assumptions. Tooby and Cosmides (1992) referred to this paradigm the "Standard Social Science Model" (SSSM), which was introduced in Chapter 1. More specifically, the assumptions and postulates of the SSSM include the following.
The SSSM assumes that at some point in human evolution human intelligence evolved to some critical level of complexity. Once it had reached that point the human mind had acquired the "capacity for culture" (rather like a computer that has the capacity to run any program). As infants, humans are all presumably endowed with the same content-free, domain-general learning mechanism. Domain-general brain/mind processes operate the same regardless of the information input or problem to be solved, and this allows the learning of virtually any behavior with equal ease. Human behavior may "evolve," but only in an ontogenetic (developmental) sense as the behavior of an individual is selected by social reinforcement and punishment. As individuals are socialized by their culture, they eventually come to resemble other members of that culture. Culture is the "programmer" of the general-purpose human brain/mind. Causality flows from culture to mold the individual, not vice versa.
In the SSSM, psychology and cultural anthropology work synergistically. Psychology (especially social learning theory) identifies and describes the general learning processes (e.g., reinforcement, punishment, extinction, habituation, observational learning), and cultural anthropology supplies a variety of examples of the unlimited varieties of behavior that different cultures can produce. Because the brain/mind is initially content free, the social sciences can be conceptualized as disciplines separate from, and independent of, biology. Culture is transmitted generation after generation via the process of socialization, as indicated in the following diagram.
In the SSSM, the two sexes are presumed to have identical general purpose learning mechanisms. Average group differences between the sexes are therefore due to differential socialization of each sex. Because socialization practices vary in different cultures, the variability in sex roles that Margaret Mead purportedly found in New Guinea and Samoa is exactly what one would expect to find. More generally, if we were to randomly sample the "sex roles" in cultures widely separated in time or place, the SSSM predicts we would find random variation in gender dimorphic behavior. The random variability between cultures might look something like the hypothetical situation presented in Diagram #, regardless of the sex difference diagrammed, e.g., physical aggression, desire for sexual partner variety, investment in offspring, risk taking behavior, sexual jealousy, etc.
Random Variability in Sex Role Behavior Predicted by
the SSSM in a Set of Hypothetical Cultures
The assumptions of the SSSM may initially appear reasonable. We have all "felt" praise and punishment, we know how it feels to be ignored, and we have all imitated the behavior of others. During our life, we have seen our own behavior "evolve" as a consequence of socialization in our own culture. However, despite the intuitive appeal of the SSSM, a convergence of theory and data in neuroscience, cognitive psychology, artificial intelligence, and evolutionary biology suggest that it has several serious shortcomings (Cosmides & Tooby, date). For example, research in artificial intelligence suggests that the a content-free, domain-general information processor that the SSSM assumes to be characteristic of the human brain/mind is an impossibility.
Like the human brain/mind, at first impression a computer may also appear to be a domain general machine. It can do a variety of tasks, such as word processing, playing chess, producing music, surfing the web, and searching databases -- so it initially appears to be a domain general machine. On closer inspection, however, a computer can be seen to have extremely domain-specific physical components. But with only these mechanisms it can do nothing -- it still must be preprogrammed with many domain-specific software procedures before it can do anything useful. It cannot produce useful output unless it is preprogrammed to "know" how to process certain types of input. Even computers programmed with software that can "learn" have a large number of preprogrammed rules that make learning itself possible.
The Integrated Model suggests that the human brain, too, is preprogrammed to solve a variety of problems. Far from being a content-free tabula raza, humans are born "pre-wired" (or are "wired up" during normal development) with a set of mental mechanisms designed by natural selection to solve the survival and reproductive problems that repeatedly confronted our ancestors. These domain-specific modules not only guide learning in certain directions, but also make learning itself possible.
One of the goals of the Integrated Model is to identify and understand the operation of domain-specific "mental organs." In total, mental mechanism can be conceptualized as human nature. All humans have a "physiological nature" (we all have livers, hearts, kidneys -- all designed to solve domain-specific problems). The Integrated Model suggests that all humans also share a psychic unity -- we all share the same "psychological nature" (consisting of a set of species-wide "mental organs" to solve domain-specific problems). These information-processing modules are triggered by specific types of input (certain environmental or social situations), and the information is analyzed using a particular set of procedures or decision rules. Most of these procedures are not simple, rigid "instincts," but flexible and facultative cognitive heuristics that tend to guide one toward historically adaptive solutions. Such modules resulted in problem solving that, on average, increased the reproductive success of our ancestors.
These ideas about mental mechanisms may seem counter-intuitive to you. Most of this problem solving takes place without conscious awareness. Just as we are not conscious of the problem-solving activities of our body organs (e.g., we don't feel our liver extracting toxins from our blood), neither are we conscious the functioning of the great majority of our mental mechanisms. In addition, since evolution requires many generations to design mental modules, we've never observed, or "felt," one evolve, at least not in the same way that we have consciously felt the impact of socialization. We may, however, experience the output of these modules as emotions (desires, fears, aversions, etc.) or physical sensations (pain, "butterflys in the stomach," pleasure, etc.). But when we do, we don't know where these feelings come from. They just "are," they don't seem to demand an explanation. If asked why we wanted to eat an orange, we don't respond with answers about physiological mechanisms such as maintaining optimal levels of sugar and vitamin C in our blood. Instead we say "It tastes good." Since humans share a evolved psychic unity (the same set of mental mechanisms), we all understand what that means (although it is not much of an explanation).
The Integrated Model suggests that behavior evolves on two levels simultaneously. The first level is phylogenetic, as mental mechanisms evolve over many generations to solve the survival and reproductive problems for a species in a particular ecological niche. The second level is accomplished as evolved mental mechanisms operate to "fine-tune" behavior throughout ontogenetic development -- to flexibly solve specific problems in the current environment -- particularly in light of previous personal experience with the situation and the problem. That is, the Integrated Model suggests that when we solve problems, we do so with the benefit of two integrated processes: our own personal experience integrated with the "wisdom" we have inherited (embodied in our mental mechanisms) from our ancestors. As shown in Diagram #, an evolutionary circuit is made with each generation to select those genes that create physiological and mental mechanisms that, on average, help to increase reproductive success. Genes that have the effect of decreasing reproductive success rapidly go extinct.
The Integrated Models presumes that the two sexes, as members of the same species adapting to a particular ecological niche, for the most part share same set of evolved mental mechanisms (Buss, 1994). For example, both sexes grieve at the loss of a relative and smile when happy. Reproductively, however, the two sexes are rather like two subspecies -- each adapting to a different reproductive niche (as we learned in Chapter 4). To the extent that each sex faces a different set of reproductive problems, the Integrated Model anticipates that sex each would have evolved a somewhat different set of mental mechanisms designed to help solve these unique problems. The Integrated Model predicts that these sexually dimorphic adaptations will be found across time and cultures, as noted in Diagram #.
Non-random Cultural Variation for Sexually Dimorphic
Adaptations as Predicted by the Integrated Model
A review of some important differences between the Integrated Model and the SSSM can be seen in the following table. As noted by Cosmides and Tooby (1998, p. #), the SSSM "is no historical relic: it remains highly influential." However, as additional evidence accumulates, we believe that the Integrated Model will eventually supersede outdated and false "nature vs. nurture" dichotomies. In the future, the study of sex differences will tend to focus on sexually
Imagine that you are in a debate. Say that you have taken the Integrated Model perspective and your task is to convince a proponent of the SSSM that, for example, the average height difference between the sexes is an evolved, biological adaptation due to sexual selection. Suppose your opponent takes extreme cultural determinist position. He might argue that males are taller than females solely because of cultural factors -- that biological factors have no, or very insignificant, influence in causing this sex difference. For example, he might argue that males are preferentially provided better nutrition throughout their youth. Or that females are not encouraged to exercise. Or that females are encouraged to diet to remain thin (to look like the models in magazines), and therefore malnourish themselves and stunt their growth. Anorexia and bulimia, he points out, are primarily female disorders. Boys, on the other hand, are encouraged to muscle up for games like football. It might be argued that if these social factors were changed, and females and males were treated equally with respect to nutrition and exercise, the average height difference between males and females would disappear.
What arguments might you use to counter these points? You might take a proximate approach and try to identify the gene (or genes), or hormones (e.g., human growth hormone), responsible for the sex difference in height. Or, you might take an ultimate approach and present the evolutionary theory of sexual selection and male intrasexual competition for sexual access to females, as we examined earlier. You might present the data that suggests that this theory appears to be well corroborated in many different species. The more male-male direct fighting there is, the greater the sexual dimorphism. It is quite reasonable, you argue, to assume that the same evolutionary principles apply to humans as well. You might also attempt to make the other side shoulder the burden of proof. You point out that the sexual size dimorphism is true cross-culturally, there has never been a known culture in which females are taller, on average, than males. You pose the following question to the SSSM supporter: Why do cultures widely separated in time and place spontaneously produce similar cultural systems that cause such similar sexual dimorphism? Since cultural determinists assume that humans have no "nature", cultures should be free to vary in any direction on any trait. Cross-cultural similarities
thus tend to suggest biological causality.
Our hypothetical debate is actually quite similar to current debates between been proponents of the SSSM and the Integrated Model. How do scientists decide which side "wins?" What makes one theory better (more generally accepted by scientists) than another? Generally, a good theory must be parsimonious and explain observed data (particularly over a wide spectrum of phenomena) better than competing theories. As we discussed in Chapter 1, it is very impressive if, within its theoretical framework, a theory can explain observations that heretofore were particularly puzzling; especially those puzzling observations that other competing theories have great difficulty explaining.
As was noted at the outset of this book, males and females are far more similar than they are different. Our task here, however, is to identify the set of basic
evolved adaptations that are different in men and women. Since our focus is on sex differences, not similarities, our task is to sort through behavioral sex differences to see if we can find underlying biological sex difference "signals" among the "noise" of cultural (and within-sex) variations. Later in this chapter we will explore various research methods that are used to help identify sexually dimorphic adaptations.
The terms "sex" and "gender" are used differently by various investigators, as was noted in Chapter 2. Here, we will define "sex differences" as those average group differences that likely represent different evolved adaptations in women and men. An example of a sex difference would be the Coolidge Effect (male sexual re-arousal by a novel sexual partner), as was discussed in Chapter 6. We should expect to see cross-cultural consistency in sex differences, although the outward manifestation of the sex differences may be somewhat different in various cultures, or in certain situations.
We will define "gender differences" as those average group differences between men and women for which there is little reason to believe are evolved adaptations. Or, they may be distant and highly variable side effects (or "spandrels") of adaptations. Bone is adaptation, but the white color of bone is not -- it white because calcium is white. The color of bone is then a side effect of an adaptation. With respect to sex differences, the tendency to wear trousers or dresses, cutting one's hair short or long, or wearing makeup are not likely to be evolved adaptations. Thus, using our terminology, these are gender differences, not sex differences. We would expect gender differences to be highly variable across time and cultures.
Using our terminology, we should note that currently there is a fairly large gray area between evolved sex differences (dimorphic adaptations) and gender differences (side effects, or spandrels, of adaptations). Future research is needed to sort out some of these phenomena, including "motherese" (the tendency of mothers to talk "baby talk" to their infants), childhood toy preferences, and occupational choice. Again, if there is substantial cross-cultural consistency, it would be classified as a sex difference since it is likely a consequent of a sexually dimorphic adaptation.
As we reviewed in Chapter 4, evolutionary theory predicts a basic set of evolved sex differences. To review, gamete dimorphism results in two fundamental
differences between the sexes: (a) maximum reproductive rate (or maximum potential offspring -- males virtually unlimited/females limited) and (b) maternity/paternity differentials (females assured of maternity/males insecure about paternity). As a consequence, men and women, on average, will tend to pursue somewhat different, and to some extent conflicting, reproductive strategies. Collectively, these conflicts of reproductive interests may be termed the "battle of the sexes."
We can summarize the set of evolved sex differences, and the resulting conflict of interests between the sexes in the table below.
A. Conflicts resulting from differences in maximum potential number of offspring (and resulting higher male reproductive variance):
1. Sexual discrimination
2. Age of mate preferences
Tend to find females of high fertility (between about 17 - 28 most) sexually attractive
Tend to find somewhat older men more attractive (to the extent that somewhat older men have, on average, greater status and wealth)
3. Sexual partner variety
Tend to prefer sexual partner variety for its own sake
4. Commitment to monogamy
More commitment avoidant
More commitment oriented
5. Physical Aggression and risk taking
B. Conflicts resulting from differences in assurance of genetic parentage
6. Parental investment
Primary focus: sexual infidelity
Primary focus: commitment infidelity
C. Long term mating conflicts
Seeks sexual fidelity from partner and sexual access to partner
Sees long term commitment, resource provisioning, partner status, and protection
Husband will tend to leave if he discovers his wife’s sexual infidelity
Wife will tend to leave if her husband consumes more resources than he provides, loses status, or diverts resources to other women