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If there's indeed much more than babies involved in the reasons for sex, we're clearly not the first species to benefit from that fact. Even among the nonhuman orders, sex appears to be regularly practiced for a whole range of nonreproductive reasons with a wide range of community-building benefits. How else to explain the fact that homosexual behavior occurs in more than 450 species? How else to explain kissing among bonobos, nuzzling among zebras, literal necking among male giraffes? How else to explain the fact that some sexually active animals seem to avoid reproduction quite deliberately, mating at times that are unlikely to produce young or picking partners that are unable to do so? From 80% to 95% of a species of sea lion rarely or never reproduce, though they continue to couple. And so of course do many of us, chasing sex as passionately as the most prolific of breeders.
"How many times in your life do you think about being sexual," asks clinical psychologist Joanne Marrow of California State University, Sacramento, "and how many of those times are you thinking about reproduction?"
So what gives? And don't say simply that sex is fun. So are gardening and traveling and going to the movies, but when was the last time you woke up in the middle of the night with your heart pounding and your breath catching because of a dream you were having about a trip to Barcelona? Just as there's more to sex than babies, there's also more to it than fun.
Part of what makes touch--and by extension, sex--such a central part of the species software is that hedonism simply makes good Darwinian sense. It's not for nothing that hot stoves hurt and caresses feel nice, and we learn early on to distinguish between the two. "All creatures do things that feel good and avoid things that feel bad," says J. Gayle Beck, professor of psychology at the University of Buffalo. "The individuals who learn that best live the longest."
But mastering even so basic an idea can be a slow process, often too slow when survival is on the line. And so nature provides us with a head start. Before we have a chance to practice our first little Moro grab--before we leave the womb, in fact--our pleasure engine is humming. "Little boys can have erections from the day they're born, sometimes even in utero," says Marrow. "Both sexes get pleasure from touching themselves without having to be taught."
Once we're in the world, both nature and experience reinforce that need for physical contact, turning us into full-blown tactile bacchanalians. Nursing alone is a powerful reinforcer. The mechanics of animal nursing can be a utilitarian business, with wobbly-legged newborns standing up to drink from Mom as if she were a spigot. Human nursing, by contrast, requires flesh-on-flesh cuddling. What's more, a mother's metabolism ensures that this contact occurs more or less all day long. Anthropologist Sarah Blaffer Hrdy, professor emeritus at the University of California at Davis, points out that human beings produce very dilute breast milk, which necessitates frequent nursing sessions and therefore provides loads of opportunities for mother and child to touch.