What's the Big Idea?

In Sex at Dawn: The Prehistoric Origins of Modern Sexuality, the controversial psychologist Christopher Ryan takes on the traditional Darwinian view of human sexuality, which is based on monogamous relationships. Ryan argues this view is completely outdated, if not downright insidious, part of "the 10,000 year campaign against female sexuality."

Take the issue of female orgasm, for instance, which some scientists do not accept as a biological necessity. Dr. Elisabeth A. Lloyd, among others, has described female orgasm as the female equivalent to male nipples, anatomy that one sex needed, while the other sex "just sort of lucked out with some lingering leftovers."

Ryan rejects this view. "When a woman has an orgasm," he explains, "the pH of her reproductive tract shifts in a way that favors sperm that enter her at that point." Why is this so important? Sperm competition. In prehistoric times, according to Ryan, women had "multiple lovers at any given ovulatory cycle, even in any given sexual event."

And so, let's say a woman is having sex with several different men, and she likes them all well enough. Now let's suppose she has a special connection with one man in particular, whether it is a psychological connection or the attraction happens on the level of smell. That man provokes her to have an orgasm, and that man’s sperm has a great advantage over the sperm of the other men "in the obstacle course to the ovum."

What's the Significance?

Is it true that women are "quality players" while men are "quantity players"? Ryan says the two sexes are hard-wired exactly that way, and the proof about our sexual proclivities is written in the human anatomy. "The female, like the male body, is a book that can be read," says Ryan. "It’s full of information about the sex lives of our ancestors."

Ryan points to some cutting-edge experiments that suggest the ovum itself is "capable of distinguishing between the sperm of different men by the DNA and choosing the sperm that is the best match for her." Or, to put it another way:

It’s not that, say, Brad Pitt and Johnny Depp are fighting over who gets to mate with Angelina Jolie. It’s that they could both have sex with Angelina Jolie and the competition takes place between their sperm cells, on a microscopic level in which Angelina Jolie’s body is able to distinguish which is the best match for her.

So how did men evolve to gain advantage in the sperm competition? External testicles. Ryan describes this equipment as "like having a refrigerator just for beer in the garage. If you’re the kind of person who has a fridge just for beer, you’re expecting a party to break out at any time and you want to be prepared."

Man also has the longest, thickest penis of any of the apes. According to Ryan, the head of the penis "appears to be designed to pull back pre-existing semen [from other men] in the female’s reproductive tract."

Ryan points to research conducted by Todd Schackelford with an artificial vagina and penis and semen solution. According to Ryan, Schackelford concluded that "the repeated thrusting action of human intercourse"--that is specific to humans--"appears to be designed, along with the penis shape, to pull out the sperm of men who have already been there to give your boys a better shot at conception."

Follow Daniel Honan on Twitter @DanielHonan

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