June 21, 2013

Liza Mundy is a Washington Post staff writer on leave, a fellow at the New America Foundation and the author of “The Richer Sex: How the New Majority of Female Breadwinners Is Transforming Sex, Love, and Family.”

About 35 years ago, psychologists devised an experiment to gauge which gender is more interested in casual sex. They sent a bunch of students, male and female, around the campus of Florida State and instructed them to ask strangers, “Would you go to bed with me tonight?” To this abrupt invitation, men who were approached usually said yes; women invariably said no.

Of course women said no! From a young age, females learn that a stranger who tells you he’s been noticing you lately and finds you attractive (this was also part of the researchers’ script) is likely to be odd and scary, possibly dangerous, and the best response is to get away as fast as you can.

Astonishingly, this study still gets trotted out as evidence that women are less sexually driven than men; it is harnessed, even now, by proponents of evolutionary psychology and other theories holding that men are promiscuous animals whose reproductive strategy is to impregnate as many women as possible, while women are clinging creatures who want to enforce monogamy on men. Refuting this line of argument can put advocates of women’s sexual freedom in a bit of a bind, however: If you argue that women are in fact naturally promiscuous, or that women do crave random sex with strangers, or that women chafe at monogamy as much as men, is that really much of a feminist triumph?

Questions such as these have been engaged by a number of recent books, such as “Sex at Dawn” and “Mating in Captivity,” which explore the mystery of human sexuality, the problem of monogamy and the related distinctions — if there are any — between the genders. We seem to be at a cultural moment when our ever-lengthening lifespans have illuminated the challenges of long-term pair-bonding, and newer technologies have enabled researchers to develop more sophisticated methods of measuring desire as well as its waning.

To the ranks of such books, add“How We Do It,” by Robert Martin, a curator of biological anthropology at the Field Museum in Chicago, and “What Do Women Want?,” by journalist Daniel Bergner. The first is a tour of the evolution of reproduction in humans and other primates; the second is an inquiry into female desire, which Bergner describes as an “underestimated and constrained force” that makes women far more attracted to strangers, and far less suited to a life of staid fidelity, than the evolutionary psychologists would like us to think.

Martin, who has spent his career among owl monkeys, bush babies, mouse lemurs and other primates, including college students, approaches the “Are humans monogamous?” question by considering anatomy. On the probably-not side of the equation, he points out that humans are sexually dimorphic in the sense that there tend to be significant differences in body size between males and females. Dimorphism is also found in gorillas, which live in harems, and orangutans, which tend to be solitary and are not pair-bonding. Among those few non-human primates, such as gibbons, that do monogamously pair-bond, males and females tend to be similar in size. Then again, male and female chimps are also close in size but shockingly wanton, so there is no clear rule of thumb.

Complicating the picture further, Martin points out that in human females, the oviduct — the passage where egg and sperm usually meet — is short, and, relatively speaking, human male testes are small. Both suggest that we are not designed for competitive copulation, in which the sperm of different males must race to reach the egg. So the design of our reproductive systems suggests that we are not built for promiscuity.

In short, here is what comparative primate anatomy tells us about whether humans are monogamous: nothing!

In Bergner’s book, some of the same questions are being explored by a growing number of female scientists, who, like those brave three female justices on the Supreme Court and the female members of the congressional Armed Services committees, are venturing into a historically male-dominated field. In this case, that would be the field of female sexual desire. Illustrating how monogamy can be a problem for women, Bergner profiles researchers, as well as patients and other interview subjects, whose mate dissatisfaction and elaborate fantasies belie the comment, made long ago by the British gynecologist William Acton and quoted by Bergner, that “the majority of women, happily for society, are not very much troubled by sexual feeling of any kind.”

Countering the idea that men are far more open to sex with strangers, Bergner spends time with a number of scientists who are connecting women to devices, exposing them to pornography and other photos, monitoring their physical response and finding — lo and behold — that women are indeed turned on by images of men they don’t regularly have breakfast with. But this does not feel like much of a victory, since the female subjects we meet in passing talk mostly about what is wrong with their relationships and feelings and partners. Surely women could have been found who were not so bored and miserable, and if they had been, the book — which is making a valuable point — would have felt more balanced.

One reason these scientists can get funding is that pharmaceutical companies are looking for a “female Viagra,” in the wake of the financial bonanza the male variety turned out to be. In one of the more depressing sections of Bergner’s book, he points out an impediment, however: the fear that such a drug might work too well. Among corporate reps and FDA bureaucrats, there is some concern about “creating the sexually aggressive woman,” presumably out of fear that mayhem would result, a lot of unreasonable demands would be made, and the collapse of Western civilization would finally happen. “There’s this idea of societal breakdown,” one adviser tells Bergner.

Reading both books, one reflects on how difficult it is for anybody to get at the innate truth of women’s sexual response, given the environments that women — and men — are exposed to. In the buses of India and the villages of Afghanistan and the barracks of the U.S. military, controlling and violating women’s sexuality remains a horribly frequent way of controlling women’s behavior, depriving them of autonomy and making it clear how unwelcome their presence can be. No wonder scientists who want to study women’s desire lock themselves in cinderblock labs to try to get at the essence. The thing is, such an environment cannot duplicate real life, with all its complexities and mixed messages.

Martin’s book is concerned with more than sexuality. His goal is to enlighten us about how our reproductive systems developed, with excursions into how other species have adapted. Fish and amphibians, he points out, can simply “release eggs and sperms into the water around them, and fertilization takes place externally.” During millions of years of evolution, the fertilization and nourishment systems developed by birds, reptiles and mammals — eggs, wombs, pouches — are all, in their own way, responses to having left the water. To reproduce, we have to find a way to re-create the ocean within ourselves.

Among the more intriguing sections is Martin’s discussion of such puzzles as morning sickness: As humans developed a varied, omnivorous diet, it may be that morning sickness developed to protect the fetus from toxins. There are other interesting factoids: 2 a.m. is the peak time for labor to commence. A great many mammal mothers swallow their babies’ waste. Human babies cannot cling the way other primate babies can, but they do crave close contact, which is why they love being carried.

Not necessarily on purpose, both books illuminate the problem with attempts to understand our current reproductive behavior by looking at our evolutionary past. As Martin points out, the main reason males and females come together to produce offspring — the reason we don’t replicate asexually, by cloning — is that sexual reproduction gives us a chance to reshuffle the genetic deck, to mix up our gene line in response to “new selection pressures” brought on by changing environments. Often, theorists of mating behavior invoke our prehistoric origins: Oh, if that’s how the hunters and gatherers lived — men hunting, women seeking hunters — then that’s how humans are innately designed. But the very fact that humans have sex is proof that we are a forward-looking species, equipped to adapt and change.

Martin’s book also reminds us that things could have been different: If we had taken to laying eggs, like birds, how much easier professional life would have been for women; external incubation and feeding make it so much easier for Dad to pitch in from the get-go.

And some things still could change. Martin points out that there’s no good reason women have borne the brunt of contraception. Over the years, women have been expected to inject and insert and ingest any number of substances and devices in the interest of controlling family size. Whereas men — well, Martin shows that quite a few experiments have proved that warming the testes is effective. And there are so many ways to do it! Submerging men in hot water up to their necks, fitting insulated underwear, 30 minutes of exposure to a 150-watt light bulb, slings worn over the crotch for an extended time period: All these methods have been shown to lower sperm counts. “Heating testes is safe, effective, and reversible,” Martin points out.

For some reason, there is no evidence that the FDA is looking into this.

Liza Mundy is a Washington Post staff writer on leave, a fellow at the New America Foundation and the author of “The Richer Sex: How the New Majority of Female Breadwinners Is Transforming Sex, Love, and Family.”

WHAT DO WOMEN WANT?

Adventures in the Science
of Female Desire

By Daniel Bergner. Ecco. 210 pp. $25.99

HOW WE DO IT

The Evolution and Future
of Human Reproduction

By Robert Martin. Basic. 304 pp. $27.99