Darwin, James, and Functionalism
In 1859, Darwin published The Origin of Species, in which he proposed that the immense variety of plant and animal species in the world arose over many years from a few common ancestors through the process of natural selection. This process is often known by the phrase “survival of the fi ttest.” Although Darwin wrote long before genes were understood in biological terms, he hypothesized that variations occur occasionally in the process of inheritance. Today, these variations are known to be based on spontaneous changes in a gene, known as mutations. Suppose a gene mutation produces a variation such as bright red feathers on a male bird’s breast. If red feathers increase the likelihood that the bird will reproduce and its offspring will survive (because the red feathers attract healthy female mates), the mutant gene will be “selected” (passed on to the next generation), because male birds with red feathers are more “fi t” in the competition to reproduce. In some cases, enough offspring of the red-breasted bird survive to eventually produce a stable new species. Usually, how- ever, mutant genes produce a less healthy animal, and the mutation is lost when that animal fails to reproduce. Only the fi ttest new organisms based on genetic mutations survive. In evolutionary terms, fi tness simply means reproducing offspring who pass the mutated gene on to future generations.
Evolutionary Psychology
Evolutionary psychology is the perspective in psychology that is based on the assump- tion that our evolutionary past holds the keys to understanding our current psychologi- cal characteristics (Buss, 1995, 1999; Confer & others, 2010; Puts, 2010). Evolutionary psychologists believe that the genes that infl uence human behavior and mental pro- cesses today were selected from the gene mutations that made some humans better able to survive in the past. For example, although humans learn to fear snakes and insects very readily, they are less likely to learn to fear other objects (potatoes, for example).
Evolutionary psychologists argue that it was very important during our prehistoric past (when we lived outdoors) to avoid contact with snakes. People who avoided poisonous snakes lived to reproduce more often than those who did not. Thus, a mutation that made humans more likely to fear snakes was selected and passed on to their offspring.
Over thousands of years, this trait became widespread in the human race, according to evolutionary psychologists, because it helped us survive. In the same way, evolution- ary psychologists believe that many of our most important psychological characteris- tics evolved through natural selection (Kameda, Takezawa, & Hastie, 2005).
Does this sounds familiar? Recall from chapter 1 that, more than 100 years ago, William James based functionalism on the evolutionary theory of Charles Darwin.
Although James speculated little about genetic infl uences on behavior, he believed that human psychological characteristics evolved because they helped the human species survive. In that sense, evolutionary psychology is a modern version of functionalism.
Evolutionary psychologists further believe that the variations in our genes that are one source of human diversity arose in our evolutionary past (Confer & oth- ers, 2010). A topic that is often discussed by evolutionary psychologists is gender differences in psychological characteristics (Buss, 1995; Finkel & Eastwick, 2009).
Evolutionary psychologists believe that gender differences arose in our prehistoric past because evolutionary pressures on females and males were different. This means that evolutionary psychologists believe that psychological differences between women and men are hardwired—based on genetic infl uences. This view has made
evolutionary psychology The perspective in psychology that the psychological characteristics of human and nonhuman animals arose through natural selection.
evolutionary p sychology highly controversial, in part because it appears to justify some behavior of males (such as marital infi delity) that is widely viewed as sexist (Confer & others, 2010).
Evolutionary Psychology and Gender Differences. Charles Darwin (1871) proposed that males and females in many species differ in physical appearance and behavior because past evolutionary pressures on the two sexes were different. That is, in Darwin’s view, the natural forces that determine that some mutated genes survive (because the animal with those genes lives long enough to reproduce successfully), whereas other genes perish, are sometimes different for females and males. For exam- ple, some male hummingbirds may have long and symmetrical tails because they are sexually attractive to females, and being sexually attractive to females increases the likelihood that a male’s genes will be passed on to the next generation. Female hum- mingbirds that fi nd long feathers attractive may have become common over count- less generations because long feathers are associated with genes that confer resistance to parasites (which increase the likelihood that a female’s genes will be passed on) (Geary, 1999).
Darwin’s idea of differences in natural selection for females and males has become the basis of one theory of the origin of human gender differences (Bjorklund & Shackle- ford, 1999; Buss, 1999; Geary, 1999; Puts, 2010). According to the evolutionary theory of gender differences, gender differences arose because ancestral women and men faced different evolutionary pressures during the Pleistocene era. This is when early humans survived by hunting animals with primitive weapons and by gathering wild plant foods. Evolutionary psychologists believe that there were different evolu- tionary pressures on the sexes primarily because mammalian reproduction involves a long period of gestation (pregnancy) followed by nursing and caring for the immature young. According to this theory, this pattern of reproduction had several implications that led to the evolution of the gender differences previously described:
1. Evolutionary pressures associated with hunting. Because women were physi- cally slowed by their pregnancies and had to stay close to their infants during nursing, the work of hunting large animals largely fell to men. Evolutionary theorists believe that this meant that strong, fearless males who could throw weapons accurately were more likely to survive and reproduce. Because throwing weapons at moving animals requires good spatial abilities, males with this attribute were also more likely to sur- vive and to reproduce. Eventually, men came to excel in this area, on average. There is some evidence that spatial ability is the basis of modern men’s somewhat better average performance on tests of mathematical ability (Casey, Nuttall, & Pezaris, 1997; Casey & others, 1995), suggesting that the natural selection of the best hunters may have led to men’s somewhat greater average mathematical abilities.
2. Evolutionary selection of dominance and aggression. Men could reproduce only if they could gain access to fertile women. One factor that increased the likeli- hood of mating with females during hunter-gatherer times was being stronger, more dominant, and more aggressive than male competitors (Buss, 1995; Puts, 2010).
Thus, the evolutionary pressure to fend off male competitors selected these features in males. In contrast, no such pressures existed in our past that selected for aggres- sion and dominance in females.
3. Evolutionary pressures created by child care. The care of young children had to fall to women during these ancestral times because nursing was the only reliable way to nourish infants. Evolutionary theorists suggest that women were more suc- cessful in raising young children when the women banded together in groups large enough to scare off predators that might kill their young (Bjorklund & Kipp, 1996;
Buss, 1995; Geary, 1998). Because women who were sociable, cooperative, verbal, and nonaggressive were most likely to be accepted in such groups, the children of
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women with these traits were more likely to survive and pass their genes on to future generations of females. Thus, according to this theory, women’s need to raise chil- dren in groups created evolutionary pressures that shaped their social, emotional, and cognitive functioning.
4. Evolutionary pressures created by gender differences in parental invest- ment. Because ancestral women were pregnant and nursing for long periods with each child, their level of investment in each individual child was very high. That is, because women could give birth to only a relatively small number of children, it was important that each offspring survive if the mother’s genes were to be passed on (Bjorklund & Kipp, 1996; Geary, 1998). In contrast, because the only contribution to reproduction that males were required to make was copulation, they could maximize the chances that their genes would be passed on by having sex with as many fertile females as possible.
According to evolutionary theory, men tend to prefer younger, attractive women because youthfulness and the facial, hip, and breast characteristics that men fi nd attrac- tive are associated with reproductive health and fertility (Geary, 1999). The fact that fertilization is hidden inside the female body also contributes to the different evolu- tionary pressures for the two sexes. Although a female always knows she is the mother of every child she gives birth to, a male cannot be certain that he is the father; the female could have had sex with another male without his knowledge. These facts of reproductive life meant that the level of parental investment of males in each offspring was lower than for females, according to evolutionary theorists (Bjorklund & Kipp, 1996; Buss, 1995; Geary, 1998).
Evolutionary theorists believe that this is why modern males evolved to be sexu- ally jealous and controlling of women (to reduce the chances that they would bear the child of another man) but also to be comfortable with the idea of promiscuity for themselves (because this could increase the number of children with their genes).
5. Evolutionary pressures in mate selection. Because women are limited in their ability to gather food during some parts of pregnancy and child rearing, they and their offspring are most likely to survive if their mates help support them. Thus, women have evolved to prefer mates who have physical prowess and the social status and skills that come with age, who have fi nancial resources, and who have good char- acter (Buss, 1995; Geary, 1998; Puts, 2010). According to this view, women select such men because they will help them and their offspring survive. Because women depended on the help of men during ancestral times, evolutionary theory suggests that this is why they are more likely to be upset by emotional infi delity (which could mean that the male would help another female survive) than sexual infi delity.
Critique of Evolutionary Theory. What do you think of the evolutionary theory of gender differences? Some people fi nd it to be highly revealing. Others feel that it is a self-serving attempt by men to justify their aggression, promiscuity, and shirking of child care. In addition, it is troubling to many that evolutionary theory implies that women and men are locked into gender differences by their genes.
Evolutionary theory has been criticized on a number of scientifi c grounds as well.
First, evolutionary theories differ from most other psychological theories because they can never be directly tested. We can say anything we want about events that happened 10,000 years ago during the Pleistocene era, but we cannot conduct formal experi- ments to put our hypotheses to the test (de Waal, 2002). Thus, some psychologists believe that evolutionary theory is better thought of as intellectual frameworks for thinking about human behavior than as a fully testable theory. In addition, some of the specifi c arguments advanced by evolutionary theorists are debatable. For example, if women’s need to band together for protection led to their greater sociability and coop- erativeness, why did men’s need to band together to hunt large animals in groups not lead to the same prosocial qualities? Since greater perceptual speed is an advantage in
hunting, why do women outperform men in this area? If gender differences in sexu- ality are inherited, why are there large differences among hunter-gatherer societies that exist today in the extent to which men control women’s sexual behavior (Eagly
& Wood, 1999)? A cogent recent paper attempts to refute many of these criticisms (Confer & others, 2010).
Social-Role Theory of Gender Differences
The major alternative to evolutionary theory is the social-role theory of gender dif- ferences (Abele, 2003; Bandura & Bussey, 2004; Bussey & Bandura, 1999; Wood
& Eagly, 2002). Its primary hypothesis is that each society’s division of labor, and the different social roles that it creates for women and men, is the force that creates psychological gender differences. That is, gender differences in behavior result from the different opportunities, challenges, experiences, and restrictions that social roles create for men and women in each culture.
In one important way, the two theories of gender differences are in agreement.
Like evolutionary theory, social-role theory agrees that some biological gender dif- ferences led to a division of labor between the genders. Thousands of years ago, the biological realities of reproduction for women and the advantages of men’s greater physical strength led most human societies to create social structures in which men had greater power and status. In turn, this difference in social status and roles—which still exists to varying degrees in virtually all human societies—led to social learn- ing experiences that taught men to be dominant, assertive, and aggressive and taught women to be submissive, cooperative, and sociable. Similarly, the childbearing and nursing role fostered the learning of helpful and nurturing behavior among women.
Although social-role theory suggests that biological sex differences created the initial push for a gender-based division of labor in the past, gender roles are maintained today by current socialization practices, not by our genes. Now that hunting animals is no longer necessary and societies are governed by laws that have rendered physical aggression less advantageous (it mostly gets you put in jail), social-role theory pos- its that many gender differences are maintained today only by social pressures that are useless vestiges of past needs. Furthermore, they hypothesize that as gender roles change in contemporary societies, the psychological differences between women and men described above will also change (Eagly & Wood, 1999). Men may knowingly or unknowingly oppose social changes that threaten their position of power, however, and women may fi nd patterns of behavior that are inconsistent with their internalized gender roles to be uncomfortable at fi rst. Thus, although changes in outdated gender roles are to be expected, they may proceed slowly and bumpily at times.
Claude Steele (1997) of Stanford University addressed the infl uence of inter- nalized gender roles on cognitive performance. He suggested that people succeed in school subjects only when achievement is part of their internalized gender role, but few North American women are socialized to view themselves as competent in math- ematics and engineering. It is these differences in socialization, rather than biological differences, that he believes create differences in performance.
Empirical support for Steele’s (1997) view comes from experiments in which expectations about performance were manipulated. In one study, women and men were asked to take a diffi cult test of mathematics skills and concepts. Half of the participants were told that it was a test on which males outperform females, whereas the remaining participants were told that it was a test that showed no gender differ- ences. When the participants were led to expect gender differences in performance, men correctly answered three times as many questions as women. When they were led to believe that there would be no gender difference, however, there was none—the women and men performed equally well (Steele, 1997). Thus, expectations of gender differences apparently can create gender differences in cognitive performance.
social-role theory of gender differences The theory that the opportunities and restrictions inherent in women’s and men’s different social roles create psychological gender differences.
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Additional support for social-role theory comes from studies that have asked whether differences in cognitive performance are more closely related to a person’s biological sex or gender identity. Kalichman (1989) found that performance on a spatial reasoning task (on which males tend to do better) was predicted better by each participant’s degree of identifi cation with the stereotypical masculine gender role than with being a member of the male sex. That is, both males and females who were more “masculine” performed better on this task than did less masculine participants. Similarly, a number of studies show that both men and women who are characterized by androgynous gender roles (high in both masculinity and femininity) perform more accurately on a wide range of cognitive tasks (Halpern, 1992; Nash, 1975; Signorella & Jamison, 1986).
Some social-role theorists have examined gender differences in mate selection to test their hypothesis that gender differences in behavior will change as social roles for women and men change (Eagly & Wood, 1999). Among 37 cultures around the world, the degree of equality between the genders (defi ned in terms of the percentage of women holding high-status jobs and political offi ce and equity in incomes) varies widely. Among the cultures with the greatest degree of gender equality, the typical pattern of males preferring younger women with good domestic skills and females preferring older men with good earning potential is weakest (Eagly & Wood, 1999).
Similarly, a study of 93 cultures found that girls are less likely to be socialized to be obedient and more likely to be socialized to be achievement-oriented in societies in which women can inherit property and hold political offi ce (Low, 1989). The same study found that boys are most likely to be socialized to be competitive in societies that allow males to have multiple wives (Low, 1989). This suggests that changing social roles could produce changes in gender differences as hypothesized by social- role theory (Peterson & Hyde, 2010).
Critique of Social-Role Theory. What do you think about the social-role theory of gender differences? Is it consistent with your intuitions about women and men?
Because it was proposed more recently, social-role theory is less well articulated than is evolutionary theory at this point. In addition, it has not yet fully addressed the sig- nifi cance of differences in the brain between women and men. It is possible that such differences could be integrated into social-role theory, however. As discussed in chap- ter 3, the brain is a plastic organ that changes with experience. Thus, female-male differences in brain structure and functioning could be the result of differences in the experiences of women and men. That is, it is possible that gender differences in the brain are actually the result of different social roles rather than the other way around.
These and other issues have not yet been fully addressed by social-role theorists.