Eve psych

Maia Szalavitz

This article originally appeared in Feed,  7 March 2000

Sarah Blaffer Hrdy was a Harvard undergraduate when she first learned about the puzzle of monkey infanticide. It was 1968, and she was studying with a scholar, Irven DeVore, who was struggling to integrate the study of nonhuman primates into anthropology. The problem was that male langur monkeys in India had been seen killing baby langurs. Even more disturbing, the mothers of the dead babies would willingly mate with the killers after the murder.

Langur monkey infanticide turned out to be one of those curious problems that launches an entire intellectual odyssey. By 1971, Hrdy ('They say my husband married me to buy a vowel,' she jokes) was in India, observing the leaf-eating langurs. Previous researchers had theorized that the infanticide resulted from 'crowding' in langur territories, caused by human encroachment. Their murderous behavior certainly didn't seem to favor their species, and it was hard to believe that these monkeys, a Buddhist symbol of the positive value of service to others, could be so heartless.

For the next nine years, Hrdy would study the life cycle of the langurs, following the monkeys in villages and in forests, and examining varying population sizes. In the end, she developed a dramatically different hypothesis, one that contributed significantly to the nascent field of sociobiology.

The langurs, according to Hrdy, were not behaving abnormally in the presence of humans - rather, the males were acting in their own genetic interests. Male langurs killed babies only when they had newly entered a troupe and could be sure that those babies weren't theirs. This would put the mothers quickly into estrus - which meant that the males could then ensure their own genetic legacy by mating with them. While many females put up a fight for their babies, often helped by female relatives, once they lost, they voluntarily mated with the killer. This essentially cut the females' losses, since it was the fastest and safest way to reproduce again. As modern evolutionary theory suggests, langurs favor their own reproductive future and that of their relatives - they don't seek to help all of their kind.

This evolutionary framework 'explained my problem, so I thought it was very powerful,' says Hrdy, who is the author of the recently published Mother Nature: A history of mothers, infants and natural selection. Hrdy became part of a group - which included DeVore, E O Wilson, Robert Trivers, George Williams, and others - who developed the field of sociobiology in the seventies. They used evolutionary ideas to explain both animal and, more controversially, human behavior. By examining how the selfish interests of creatures determined to pass on their genes created the wide variety of behavior - and even sometimes a great deal of cooperation - they offered new insight into the patterns and problem-solving of Nature.

At that time, however, sociobiology was about as popular with women as a narc at a pot party. With its emphasis on evolutionary explanations for behavior, sociobiology was seen as saying that biology was destiny - while most in the academy and in progressive politics were still living under the Margaret Mead/Franz Boas paradigm, which held that human nature was infinitely flexible and could be reshaped in any form a culture desired. With the women's movement beginning to take off, feminists saw sociobiology as an attempt to keep them in their place, to show women that evolution dictated that they be nothing more than child-rearing machines. Most saw it as an attempt by a male-dominated field to continue to maintain its hegemony.

And indeed, early sociobiology was highly sexist, like many areas of science at the time. Hrdy, who had her first child in 1977, was dismayed to learn that one of her mentors told a newspaper reporter covering the issue of working mothers that 'My own view is that Sarah ought to devote more time and study and thought to raising a healthy daughter. That way misery won't keep traveling down the generations.'

Despite the insult - her work with langurs is considered amongst the most important work in the field and is still taught as such - Hrdy continued to believe that science would eventually weed out sexism. Surprisingly, she was not alone. Today, many of the top researchers in the field are women, and it is actually one of the least male-dominated fields in science. Newly rechristened 'evolutionary psychology,' the field continues to attract controversy - particularly over its theories about gender differences - but it has also attracted a powerful cadre of women who see the field as extending the project of feminism, rather than betraying it.

Though critics like Pulitzer Prize-winning New York Times reporter Natalie Angier continue to deride evolutionary psychologists as sexist 'evo-psychos,' evolutionary theories about human behavior have quietly come to dominate the hottest areas of psychological study. Most neuroscientists, psychopharmacologists, and psychologists who study perception have long accepted evolutionary principles as givens. They are studying biological phenomena, after all, and evolutionary theory suggests that most biological phenomena arose to solve biological problems.

When you start to apply any of these principles to human behavior, things get more complicated, however - and much more political. It's quite reasonable to say that human eyes evolved for seeing, for example, but another thing altogether to claim that, all else being equal, men prefer younger women because their ancestors who chose younger women had more offspring. With eyes, there are no counter examples: they all do the same thing. But all things in human courtship are rarely equal and men and women behave in a widely variable fashion, influenced both by their own desires and by their culture.

According to its advocates, evolutionary psychology doesn't rule out cultural influences, it tries to explain them. Margo Wilson is the former head of the largest professional society for evolutionary approaches to behavior, and is highly respected for her research on the causes of homicide. She says she agrees with those who say that culture constructs 'every moment, all the time.' But that presupposes another question: 'How come things are more likely to get constructed one way rather than another?'

To answer that question, evolutionary psychologists frequently focus on differences between the sexes, because, as Leda Cosmides, of the University of Southern California at Santa Barbara says, 'They make predictions, which are testable.' They also make the field an easy target in the gender wars.

Take the question of women and work. It is clear that in the environment where humans evolved, women stayed close to their babies throughout infancy. However, evolutionary psychologists point out, women worked as well. In hunter-gatherer societies, gathering by women provided up to seventy-five percent of the nutrition for the group, since hunting was only sporadically successful. Women usually carried their babies while foraging (sometimes walking hundreds of miles carrying a one-year-old), but there was also widely available 'day care' - sisters, aunts, husbands, and teenage relatives who could 'baby sit.'

Though conservatives like to use evolutionary psychology to justify stay-at-home motherhood, the picture it presents is much more complicated. A mother at home alone with child-rearing as her only task is far from 'natural' in human history. Neither, however, is one spending most of her time far from her infant - and both facts are reflected in the conflicts felt by many mothers today who must make choices between work and family that were never faced in the ancestral environment.

Another politically charged question is that of whether males and females have different levels of sexual desire. Some have claimed that women's desire for fewer partners means a lower female sex drive. Others say women want fewer partners because men stigmatize those who want many - and that liberated females would want casual sex as much as men do.

Here's an evolutionary perspective: Because childbearing and rearing are more costly to a woman, it is to her advantage to be at least somewhat choosy. This doesn't limit desire for frequent sex with a chosen partner (as many married men report), - but it probably does make women less likely to seek numerous partners. For a man, however, the only definite 'cost' of sex is a few minutes of pleasure and ten cubic centimeters of sperm - and potentially, he could impregnate numerous women simultaneously. Thus, there is greater desire for more and different partners.

This idea wasn't developed to justify male misbehavior - it reflects a pattern throughout the animal world. In rare species like seahorses, where males make a greater parental investment than females, the females are the larger, more promiscuous, and more aggressive sex. But in humans, it's not as simple as men are horndogs and women are Sandra Dee clones. For both genders, monogamy is a compromise. Though men may have a greater desire for infidelity, women aren't angels either: the desire to foster genetic diversity amongst their offspring and the need to have another male provision them if their primary mate dies or runs off encourage female drives for additional sexual partners.

Hrdy points out that monogamy works for women only if fathers are consistent, reliable providers. If they are likely to die or leave, it may be to a woman's advantage to convince several men that each of them is the potential father of her child. That way, although she may get less from each, she will not be left totally stranded if she loses one.

This can be seen most readily in preagricultural societies, few of which currently exist. However, there are some South American tribes in which fatherhood is believed to be a collective effort. Their languages include words to describe 'the father who put it in,' 'the men who stirred it up,' and 'the fathers who provided the child's essence.' Even in these tribes, male jealousy can be a problem, however, and if a woman tries to convince too many men that they are a child's father she may find that all of them abandon her. Sociobiologists, noting the rarity of these cultures have also tended to downplay their importance.

As a result, opponents of evolutionary psychology have continued to caricature the field as describing all men as rapacious and marriage-phobic while women remain coy and virginal. But once again, the plot thickens. First, marriage offers at least as much to men as it does to women. Because women always know a child is theirs, but paternity can be doubtful, marriage offers men control over women which can reduce the odds that they will raise other men's children. 'Around the world, men have used things like chastity belts, veiling, markers like wedding bands, foot-binding, even genital mutilation,' to try to prevent being cuckolded, according to Wilson. 'In the evolutionary context, they have a certain function, but the methods look very different in different cultures.' If women had little sex drive, such measures wouldn't be ubiquitous; if men didn't want marriage, it wouldn't exist.

Rape is yet another hot-button issue. None of the researchers I spoke with thought it was problematic to pose an evolutionary explanation for rape as a recent controversial book, The Natural History of Rape, does - but the current data on it is scant and difficult to interpret. In fact, the two authors of the book, Randy Thornhill and Craig T Palmer , disagree on whether men have a biological propensity toward rape itself or whether rape results from a combination of other drives. Many scientists have criticized the book for speculating well beyond what the limited data actually suggests.

One constant problem in evolutionary psychology is the so-called 'naturalistic fallacy' - the idea that what is is exactly what ought to be. For example, if nature gave men a tendency to rape in certain circumstances, this wouldn't make rape moral - nor would it make it inevitable. Tendencies provoke feelings and desires - not automatic actions.

'These are statistical generalizations, ' says Helena Cronin, co-director of the Centre for Philosophy of Natural and Social Science at the London School of Economics. 'Not all women are X, not all men are Y. We're talking about dispositions and potentials -- not there's a gene inside that you will robotlike perform its will.'

'Some animals do behave in a robotic fashion.' she says. 'Some wasps have six steps to build a nest, and if I interfere with one of them, they will do the whole routine again; it's utterly inflexible. But it's an excellent design for wasps, which is why they are still here.

'For humans, what natural selection did was build very large brains with a lot of potentialities and dispositions. We are very sensitive to the environment - far from being rigid, we're the opposite. If I find myself in this position, I do this, in that position I do another thing. There is no particular reason why genes should be more deterministic than environmental factors.'

Thus, Cronin doesn't find evolutionary ideas about behavior restrictive or dangerous. 'I'm Jewish,' she says. 'I come from a family who lost people in the camps. People are understandably wary because of concerns about eugenics - but I feel the opposite way. Because these ideas have been misused, that's a good argument to do good science.'

Cosmides, who co-directs USC's Center For Evolutionary Psychology, feels similarly about evolutionary psychology's implications for feminism. 'If you want to change the relationship between men and women, you want to understand the cognitive mechanisms that govern how we interact. If you don't understand that, you don't have a prayer of changing it. It's completely wrong to say that if something is a part of our evolved architecture, then it cannot be changed.'

She compares ignoring biological differences between men and women with ignoring the biology of nearsightedness. 'If you didn't want to believe it was biological, you wouldn't figure out how to make lenses. For me, the default is to be nearsighted and I use contact lenses - I'm not 'struggling against' an innate tendency, I easily see well because we understand optics. If we understand the mechanisms that underlie behavior well enough, we won't necessarily have to fight against them, but could flip into a different mode because the mechanisms depend on context.'

Hrdy is slightly more critical of her field. Her book Mother Nature points out how evolutionary biologists have ignored females and how idealistic notions of motherhood have prevented many from seeing the strategic intelligence used by women and girls. She also believes that some major researchers ignore evidence of polyandry (women with more than one husband or main partner) and continue to bring sexist biases into their research.

Nonetheless, she remains a firm believer in the field's underlying premise. 'A lot of feminists were turned off by evolutionary biology - and they were not turned off without reason. But please, listen now.

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