Sex at Dawn полностью

For various reasons, prehistoric harems were unlikely for our species. The famed sexual appetites of Ismail the Bloodthirsty, Genghis Khan, Brigham Young, and Wilt Chamberlain notwithstanding, our bodies argue strongly against it. Harems result from the common male hunger for sexual variety and the post-agricultural concentration of

power in the hands of a few men combined with low levels of female autonomy typical of agricultural societies. Harems are a feature of militaristic, rigidly hierarchical agricultural and pastoral cultures oriented toward rapid population growth, territorial expansion, and accumulation of wealth. Captive harems have never been reported in any immediate-return foraging society.

While our species’ shift to moderate body-size dimorphism strongly suggests that males found an alternative to fighting over mating opportunities millions of years ago, it doesn’t tell us what that alternative was. Many theorists have interpreted the shift as confirmation of a transition from polygyny to monogamy—but that conclusion requires us to ignore multimale-multifemale mating as an option for our ancestors. Yes, a one-man/one-woman system reduces competition among males, as the pool of available females isn’t being dominated by just a few men, leaving more women available for less desired men. But a mating system in which both males and females typically have multiple sexual relationships running in parallel reduces male mating competition just as effectively, if not more so. And given that both of the species closest to us practice multimale-multifemale mating, this seems by far the more likely scenario.

Why are scientists so reluctant to consider the implications of our two closest primate relatives displaying the same levels of body-size dimorphism we do? Could it be because neither is remotely monogamous? The only two “acceptable” interpretations of this shift in body-size dimorphism appear to be:

1. It indicates the origins of our nuclear family/sexually monogamous mating system. (Then why aren’t men and women the same size, like gibbons?)

2. It shows that humans are naturally polygynous but have learned to control the impulse, with mixed success. (Then why aren’t men twice the size of women, like gorillas?)

Note the assumption shared by both these interpretations: female sexual reticence. In both scenarios, female “honor” is intact. In the second interpretation, only the male’s natural fidelity is in doubt.

When the three most closely related apes exhibit the same degree of body-size dimorphism, shouldn’t we at least consider the possibility that their bodies reflect the same adaptations before we reach for farfetched, if emotionally reassuring, conclusions?

It’s time to go below the belt..

No case interested and perplexed me so much as the brightly colored hinder ends and adjoining parts of certain monkeys.

CHARLES DARWIN⁶

It seems men weren’t fighting much over dates for the past few million years (until agriculture), but that doesn’t mean Darwin was wrong about male sexual competition being of crucial importance in human evolution. Even among bonobos, who experience little to no overt conflict over sex, Darwinian selection takes place, but on a level Darwin himself probably never considered—or dared discuss publicly, anyway. Rather than male bonobos competing to see who gets lucky, they all get lucky, and then let their spermatozoa fight it out. Otto Winge, who was working with guppies in the 1930s, coined the term sperm competition. Geoffrey Parker, studying the decidedly unglamorous yellow dungfly, later refined the concept.

The idea is simple. If the sperm of more than one male are present in the reproductive tract of an ovulating female, the spermatozoa themselves compete to fertilize the ovum. Females of species that engage in sperm competition typically have various tricks to advertise their fertility, thereby inviting more competitors. Their provocations range from sexy vocalizations or scents to genital swellings that turn every shade of lipstick red from Berry Sexy to Rouge Soleil.⁷

The process is something of a lottery, where the male with the most tickets has the best shot at winning (hence, the chimp and bonobo’s huge sperm-production capabilities). It’s also an obstacle course, with the female’s body providing various types of hoops to jump through and moats to swim across to reach the egg—thus eliminating unworthy sperm. (We’ll examine some of these obstacles in following chapters.) Some researchers argue that the competition is more like rugby, with various sperm forming “teams” with specialized blockers, runners, and so on. Sperm competition takes many forms.