Sex at Dawn

Bleak, no? Conventional evolutionary theory assures us that all you scheming, gold-digging women reading this are evolved to trick a trusting yet boring guy into marrying you, only to then spray on a bunch ofperfume and run down to the local singles club to try to get pregnant by some unshaven Neanderthal as soon as hubby falls asleep on the couch. How could you? But before male readers start feeling superior, remember that according to the same narrative, you evolved to woo and marry some innocent young beauty with empty promises of undying love, fake Rolex prominent on your wrist, get her pregnant ASAP, then start “working late” with as many secretaries as you can manage. Nothing to be proud of, mister.

Extended Sexual Receptivity and Concealed Ovulation

Unlike her closest primate cousins, the standard human female doesn’t come equipped with private parts that swell up to double their normal size and turn bright red when she is about to ovulate. In fact, a foundational premise of the standard narrative is that men have no way of knowing when a woman is fertile. As we’re supposed to be the smartest creatures around, it’s interesting that humans are thought to be almost unique in this ignorance. The vast majority of other female mammals advertise when they are fertile, and are decidedly not interested in sex at other times. Concealed ovulation is said to be a significant human exception. Among primates, the female capacity and willingness to have sex any time, any place is characteristic only of bonobos and humans. “Extended receptivity” is just a scientific way of saying that women can be sexually active throughout their menstrual cycle, whereas most mammals have sex only when it “matters”—that is, when pregnancy can occur.

If we accept the assumption that women are not particularly interested in sex, other than as a way to manipulate men into sharing resources, why would human females have evolved this unusually abundant sexual capacity? Why not reserve sex for those few days in the cycle when pregnancy is most probable, as does practically every other mammal?

Two principal theories have been proposed to explain this phenomenon, and they couldn’t be more different. What anthropologist Helen Fisher has called “the classic explanation” goes like this: both concealed ovulation and extended (or, more accurately, constant) sexual receptivity evolved among early human females as a way of developing and cementing the pair bond by holding the attention of a constantly horny male mate. This capacity supposedly worked in two ways. First, because she was always available for sex, even when not ovulating, there was no reason for him to seek other females for sexual pleasure. Second, because her fertility was hidden, he would be motivated to stick around all the time to maximize his own probability of impregnating her and to ensure that no other males mated with her at any time—not just during a brief estrus phase. Fisher says, “Silent ovulation kept a special friend in constant close proximity, providing protection and food the female prized.”¹⁸ Known as “mate guarding behavior” to scientists, contemporary women might call it “that insecure pest who never leaves me alone.”

Anthropologist Sarah Blaffer Hrdy offers a different explanation for the unusual sexual capacity of the human female. She suggests that concealed ovulation and extended receptivity in early hominids may have evolved not to reassure males, but to confuse them. Having noted the tendency of newly enthroned alpha male baboons to kill all the babies of the previous patriarch, Hrdy hypothesized that this aspect of female sexuality may have developed as a way of confusing paternity among various males. The female would have sex with several males so that none ofthem could be certain of paternity, thus reducing the likelihood that the next alpha male would kill offspring who could be his.

So we’ve got Fisher’s “classic theory” proposing that women evolved their special sexiness as a way of keeping one man’s interest, and Hrdy saying it’s all about keeping several guys guessing. Fisher’s theory fits better with the standard model, in which females trade sex for food, protection, and so forth. But this explanation works only if we believe that males—including our “primitive” ancestors—were interested in sex all the time with just one female. This contradicts the premise that males are hell-bent on spreading their seed far and wide, while simultaneously protecting their investment in their primary mate/family.