Sex at Dawn

These results are often cited as confirmation of the male parental investment-based model. They appear to reflect the differing interests the model predicts. A woman, according to the theory, would be more upset about her partner’s emotional involvement with another woman, as that would threaten her vital interests more. According to the standard model, the worst-case scenario for a prehistoric woman in this evolutionary game would be to lose access to her man’s resources and support. If he limits himself to a meaningless sexual dalliance with another woman (in modern terms, preferably a woman of a lower social class or a prostitute—whom he would be unlikely to marry), this would be far less threatening to her standard of living and that of her children. However, if he were to fall in love with another woman and leave, the woman’s prospects (and those of her children) would plummet.

From the man’s perspective, as noted above, the worst-case scenario would be to spend his time and resources raising another man’s children (and propelling someone else’s genes into the future at the expense of his own). If his partner were to have an emotional connection with another man, but no sex, this genetic catastrophe couldn’t happen. But if she were to have sex with another man, even if no emotional intimacy were involved, he could find himself unknowingly losing his evolutionary “investment.” Hence, the narrative predicts—and the research seems to confirm—that his jealousy should have evolved to control her sexual behavior (thus assuring paternity of the children), while her jealousy should be oriented toward controlling his emotional behavior

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(thus protecting her exclusive access to his resources).

As you might guess, the mixed strategy referred to earlier would follow similar lines. The male’s mixed strategy would be to have a long-term mate, whose sexual behavior he could control—keeping her barefoot and pregnant if poor, foot-bound and pregnant if Chinese, or in high heels and pregnant if rich. Meanwhile he should continue having casual (low-investment) sex with as many other women as possible, to increase his chances of fathering more children. This is how standard evolutionary theory posits that men evolved to be dirty, lying bastards. According to the standard narrative, the evolved behavioral strategy for a man is to cheat on his pregnant wife while being insanely—even violently—jealous of her.

Charming.

Although the survival odds of any children resulting from his casual encounters would presumably be lower than those of the children he helps raise, this investment would still be wise for him, given the low costs he incurs (a few drinks and a room at the Shady Grove Motor Lodge—at the hourly rate). The woman’s mixed strategy would be to extract a long-term commitment from the man who offers her the best access to resources, status, and protection, while still seeking the occasional fling with rugged dudes in leather jackets who offer genetic advantages her loving, but domesticated, mate lacks. It’s hard to decide who comes out looking worse.

Various studies have demonstrated that women are more likely to cheat on their husbands (to have extra-pair copulations, or EPCs) when they are ovulating and less likely to use birth control than they are when not fertile. Furthermore, women are likely to wear more perfume and

jewelry when ovulating than at other points in their menstrual cycle and to be attracted to more macho-looking men (those with physical markers of more vigorous genes). These conflicting agendas and the eternal struggle they appear to fuel—this “war between the sexes”—is central to the dismal vision of human sexual life featured in today’s scientific and therapeutic narratives.

As Wright summarizes, “Even with high MPI [male parental investment], and in some ways because of it, a basic underlying dynamic between men and women is mutual exploitation. They seem, at times, designed to make each other miserable [emphasis added].”¹⁶ Symons voices the same resignation in the first lines of The Evolution of Human Sexuality:

A central theme of this book is that, with respect to sexuality, there is a female human nature and a male human nature, and that these natures are extraordinarily different, though the differences are to some extent masked by the compromises heterosexual relations entail and by moral injunctions. Men and women differ in their sexual natures because throughout the immensely long hunting and gathering phase of human evolutionary history the sexual desires and dispositions that were adaptive for either sex were for the other tickets to reproductive oblivion.¹⁷