Free Decoding Love by Andrew Trees

symmetrical someone tends to be (studies have also found that less symmetrical men tend to have lower IQs). Think Quasimodo, and you will have an extreme version of someone who is asymmetrical. And researchers have found that women orgasm more with symmetrical men. Simply put, female orgasms appear to be largely predicated on a subconscious evaluation of a man’s genetic merit.
     
    So what does all that have to do with the orgasm as a sexual selection device? Robin Baker and Mark Ellis studied whether or not a woman’s orgasm had an effect on the amount of sperm her body retained, and what they found was that a woman’s orgasm has an enormous effect. If a woman doesn’t orgasm or has an orgasm more than a minute before the man ejaculates, she retains very little of the sperm. But if she has an orgasm less than a minute before he does or up to forty-five minutes afterward, she retains most of the sperm, which vastly increases the chances that her egg will be fertilized (they measured the “flowback”—the amount of ejaculate discharged from the vagina shortly after sex—from more than three hundred copulations, by having the women squat over a beaker). So, a man who can make a woman orgasm (i.e., a symmetrical man) has a much better chance of impregnating a woman. Scientists call this sort of hidden mechanism that helps a woman’s body choose sperm from a particular male “cryptic female choice.”
     
    All of this takes an even more disturbing turn when you bring infidelity into the equation. Remember the theory that wives are unfaithful in order to go after genetically superior sperm? It appears that the female orgasm may be actively aiding in this strategy. Another study revealed that wives who were having affairs tended to have adulterous sex at their most fertile times and that 70 percent of those copulations resulted in an orgasm (as opposed to only 40 percent of the copulations with their husbands). In other words, not only were unfaithful wives more likely to have sex with their lovers during their most fertile period, they were also more likely to orgasm and to retain a larger amount of sperm. When the researchers did the math, they discovered that a wife could have sex twice as often with her husband as with her lover but still be more likely to conceive with her lover (studies have also shown that women with regular partners fake orgasms more often, likely as a way of diverting suspicion about their fidelity).
     
    How likely is it that this sort of hidden sexual selection occurs? A lot more likely than any of us would like to believe. In one study, researchers estimated that 4-12 percent of children born in Great Britain were conceived in an environment of sperm competition, which basically means that sperm from multiple men were in the woman’s vaginal tract at the same time and competing to fertilize the same egg. The same study suggested that the majority of men and women in Western societies have at one time or another engaged in sperm competition. Another recent survey found that one in eight female respondents had sex with two or more men in a twenty-four period.
     
    Appalling as this method of “cryptic female choice” may be from a man’s point of view, it makes perfect sense from the woman’s point of view. Studies have shown that symmetrical men cheat more often, so the woman is better off going after good genes from the symmetrical man but finding a good provider somewhere else. What all this means is that, far from being some useless evolutionary by-product, the female orgasm is quite possibly a remarkably sophisticated mechanism for the selection of superior sperm.
     
    There are even a few researchers who have proposed the controversial theory that a man’s sperm are designed to war with other sperm. According to this view, fewer than 1 percent of a man’s sperm are designed to fertilize the egg. The rest are a kind of army used to prevent another man’s sperm from fertilizing the