Women After All: Sex, Evolution, and the End of Male Supremacy (17 page)

Even this, however, is not quite true, since women on average are less likely to have sex while they are menstruating, even in the modern American middle class. Many cultures discourage it, and there are some where menstrual bleeding is difficult to conceal completely or where limitations on the activities of menstruating women make those days culturally obvious. Since menstruation signals infertile days, we might think of it as a kind of anti-estrus. Also, recent and growing evidence—reviewed in 2011 by Martie Haselton and Kelly
Gildersleeve—does suggest that women unconsciously signal ovulation and that men are affected by the difference.

To take a rude example: studies show that lap dancers earn more money in tips at midcycle—something about them is making the customers put more bills in their garters—but not if they are on birth control pills, which dampen hormonal changes. Men show more jealousy on their partners’ likely fertile days, and they find unknown women’s clothing sexier and their bodily scents more pleasing during those strangers’ fertile days. In a 2014 study, Jessica Tracy and Alec Beall found that the “red dress effect,” according to which women wear red or pink more often when they are ovulating, applies strongly in winter but not in summer, when they have the option to draw attention by wearing less clothing. These and many other recent findings show that the behavioral effects of hormonal cycles have not been abolished in our species. But they are less dramatic than ape estrus; menses aside and compared to apes, women are more likely to have sex throughout the cycle.

Some background: Hunter-gatherers, also called foragers, have dramatically lower population density and social stratification than other kinds of cultures. They are also much less likely to have males living near their male relatives throughout life. This is of great potential importance to women’s status, since women have more kin at hand and more choice about where and with whom to live. Married couples may reside in groups of the husband’s kin, the wife’s kin, or both, and such wealth as there is in hunter-gatherer groups—for example, primary access to water holes and valuable tools, ornaments, and musical instruments—may be inherited through either parent. Male direct care of infants and children is greater in hunter-gatherers than in the other cultural types.

Marriage is close to universal in human cultures, but polyandry (one woman, several men) is officially recognized in just a few (the traditional estimate is around 5 percent), while polygyny (one man, several women) is commonly allowed (82 percent). (We’ll take up
some dramatic cases, including some fundamentalist Mormon sects, in
chapter 6
.) Despite this, only some men have more than one wife at a time in any culture, so monogamy has been the predominant human marriage form through space and time. This means one man and one woman
officially
together at a time—social monogamy. It does not necessarily mean complete fidelity of either; nor does it preclude several marital bonds in a lifetime. This serial monogamy is partly due to mortality; for most of human history, “till death do us part” meant an average of fifteen or twenty years. But it is also because of divorce, allowed in most cultures and common in many. Pragmatic polyandry (optimal number of fathers more than one) occurs informally in many cultures that do not officially allow it. Father-infant proximity is greatest in cultures allowing polyandry, lowest in those with general polygyny.

Katherine Starkweather and Raymond Hames showed in a 2012 study that most anthropologists have underestimated the frequency of polyandry cross-culturally. It is true that “classical” polyandry—a substantial proportion of marriages being between one woman and two or more men, usually brothers, to prevent the breakup of family farms—is characteristic only of complex societies in Tibet, Nepal, and the Marquesas Islands. But “nonclassical” polyandry is found in every part of the world. In these marriages, more than one man is officially recognized by the community as having legitimate sexual access to the same woman, with or without cohabitation, and—contrary to the conventional wisdom that this has to be bad for men—the husbands take care of each other’s children if one of them dies.

It occurs in situations where women are scarce (because of excess males or polygyny) or those in which there is extreme dependence on male contributions of food (as in Arctic hunters). In the former cases, men may decide they are better off sharing a wife and having
some
chance at reproduction rather than none; in the latter, men may realize that they need insurance for their children to survive. Either way, a woman gets to have more than one father contributing to
her
kids’
survival both now and in the future, relying not just on their alliance with each other but on their confusion about paternity. She also gets the fun of having multiple mates competing and trying to please her. Although this occurs in only a small fraction of cultures (compared to polygyny, which is formally allowed in the great majority), the cultures where it
is
allowed are often hunter-gatherers. This means that it was probably an option for our ancestors way back in the deep human past.

Some cultures, mainly in the Amazon basin, turn paternity confusion into a virtue, through the custom of
partible paternity
—the belief that a child can and should have multiple biological fathers. These cultures do not recognize singular biological paternity but say that a pregnant woman
should
have sex with more than one man so that each can contribute to the baby’s development in the womb. While this can’t happen biologically, there is evidence from some of these cultures that children with more than one “father” are more likely to survive. Some successful men may compensate by having extramarital affairs. But Sarah Hrdy’s idea of “the optimal number of fathers” certainly looks as if it applies here.

Hunter-gatherers allow polygyny but don’t have very much of it. Only among Australian aborigines did more than a third of men have two or more wives. The average for other groups is 7 to 10 percent. Polygynous men in the Australian cultures had young girls or even infants betrothed to them, and as the men aged they wound up with multiple adult wives. Accordingly, men married very late, and most young men were left to their frustrations. Why, anthropologists continue to wonder, did those old men get all the women and girls? It’s not clear even now how they got away with it.

But the rest of the world’s hunter-gatherers had much lower levels of polygyny, compatible with young women marrying around the time of menarche—at around age sixteen on average, much later than in modern societies. A few years’ difference in age at marriage together with the known lower survival rate for males could explain a
small amount of polygyny. The unmarried state in these cultures was highly undesirable and almost unknown except transiently and, for women, in old age. But we can reasonably ask, How can there have been egalitarian gender relations if polygyny was allowed?

For one thing, if polyandry was also an option, then it would not seem so unequal even if polygyny was more common. What we would have would be basically a pair-bonding species with departures in both directions. But part of the answer is how the polygyny comes about. We think of it as mainly due to male coercion, and we will encounter societies where this is indeed the case, but in hunter-gatherers men rarely have that kind of power. Hard as it is for us to believe, becoming a co-wife is often an extension of female choice: a woman may be better off as the second wife of a good hunter than as the first of a bad one. But since meat is shared beyond the family in any case, a better explanation may be the good genes hypothesis.

Women, in this view, are attracted to men who have qualities they would like in their future sons—as in one of the explanations for the peacock’s tail. They (unconsciously) seek those qualities in the men they mate with—ideally, perhaps, through monogamy with a favored male but sometimes by becoming his second wife or by having an affair with him while married to a lesser male. Why “ideally, perhaps”? Well, another ideal is for women to seek one kind of man—the reliable, androgynous, “good father type”—when they want to marry and a different kind—the erratic, masculine, “bad boy type”—when they just want sex. The best of both worlds might be to marry one and dally with the other. Ongoing studies, even in socially monogamous cultures, show that women pursue all of these strategies. For example, when asked to “choose” a husband in experiments, women prefer androgynous-looking men, but when asked to think about casual sex, they pick much more masculine types. Moreover, when they are ovulating, they lean to the more masculine even more strongly. This research has its critics, but in 2013 Kelly Gildersleeve and her colleagues answered them persuasively, reviewing “a large number of
studies providing evidence that women’s sexual motivations and mate preferences shift systematically across the ovulatory cycle.”

Much about gender relations among foragers was discussed in a pioneering book that grew out of a conference,
Man the Hunter,
edited by Richard Lee and Irven DeVore, which helped kick-start hunter-gatherer studies. But other answers came in a book that followed some years later:
Woman the Gatherer,
edited by Frances Dahlberg
.
This book pointed out the misnomer, since
Man the Hunter
itself had argued that women bring home most of the bacon—or, rather, the tubers, nuts, berries, and leafy greens. In a number of hunting-and-gathering economies, two-thirds to three-fourths of the calories came from plant foods collected by women, with only a minority supplied by men in the form of animal flesh.

Woman the Gatherer
showed, too, that archaeologists had been biased in favor of hunting. The stone tools found with human fossils starting about two million years ago were mainly used in hunting and almost certainly made by men. But the tools made and used by women—digging sticks and slings for carrying food or babies—would not have fossilized, although they would have been as vital to survival and reproduction as stone tools.

Chimps in the wild make and use a wide array of tools in many places in Africa: termite-fishing probes fashioned from twigs with their branches deliberately stripped off, leaves crumpled into sponges to soak up water from hard-to-get-at spots, larger sticks to dig in mud, logs and stones to crack nuts, and others; of all these, only nut-cracking stones would be preserved from the distant past, and they have been found in what is likely an ancient chimp habitat. Finally, females use a broader spectrum of tools in both wild and captive chimps, and the same is true of captive bonobos, although they don’t use or make tools in the wild. This evidence suggests that Laca (our common ancestor) probably already used or even perhaps made tools of perishable materials, and females may have done more of this than males.

More importantly, the scientists who contributed to
Woman the Gatherer
—Frances Dahlberg, Adrienne Zihlman, Agnes Estioko-Griffin, and others—were interested in highlighting something else that hunter-gatherer studies showed: because of small group size, low population density, and their crucial, highly reliable contribution to subsistence—today we know that it is on average about half, but that is enough—women’s voices were always heard. Almost all decisions—the ones we would call economic, judicial, and political, as well as the interpersonal—took place in conversations around the fire at night. And, depending in both sexes on age, reputation, personality, volubility, and eloquence, women as well as men would have a voice. Furthermore, while men often had to be quiet not only on solitary but even on group hunts, women’s gathering expeditions were typically peppered by conversations, and these chats built and strengthened alliances, a bit like grooming in monkeys and apes or sex between female bonobos. Women could work through problems without men and present a common front later at the fire.

Some theories suggest that men and women among hunter-gatherers should be much more different and more unequal than they are. In a 2012 study, Frank Marlowe and Colette Berbesque used data from the Hadza, an actively hunting-and-gathering group, to estimate the operational sex ratio—number of males per female capable of reproducing
today
. Given that women are fertile so little of the time in these groups—they are usually pregnant or breast-feeding—there should be more intense male competition, with a larger resulting sex difference. In theory, men should be much bigger than women, something like in gorillas.

Why aren’t they? In human females, two powerful physiological factors mute male competition. The first is (mostly) concealed ovulation. This leaves men confused about women’s fertile time and enables them to have a lot of sex outside it. Even dominant males wouldn’t be able to monopolize women for the whole time they
look
like they might be fertile. The second is menopause. Contrary to
common belief, there were quite a few older people in hunter-gatherer societies. Infant and childhood mortality was very high, giving rise to very low life expectancy at birth; but if you lived to age fifteen, you had about an even chance of seeing sixty, and the last birth, on average, was around age forty. Menopause raises the ratio because we have to count fertile men at the later ages when we can’t count women. But there are other special things about human mating and reproduction besides unique physiology.

Monogamy, however flawed, is the main mating pattern in hunter-gatherers, and that makes us largely a pair-bonding species, although with great adaptive flexibility. More important, perhaps, is the huge investment humans make in offspring. Hanna Kokko and her colleagues, summarizing fifteen years of research, asked in 2012, “Should a paternally caring male desert his young to try and breed again?” It turns out that “mating investment brings meager returns.” In other words, it doesn’t pay for hunter-gatherer men to stray so much that they put their existing children at risk.

In fact, Marlowe himself showed that among the Hadza, men do experience just such a conflict, spending less time with their children when there is an eligible young woman around. However, pregnant and lactating women depend critically on their husbands’ contribution to their food supply. Fathers also contribute a great deal to their wives and children by hunting—despite its unpredictability—among the Aché, Hiwi, Martu, and other hunter-gatherers.