MonkeyluvWell, I have some terrible news for 99 percent of us never destined to makePeople'sMost Beautiful issue and thus get to be featured in essay one. This news is so terrible that it's even been reified with a cover story inNewsweek.But first, a Martian joke:So the Martians finally come to Earth and they turn out to be great folks. Earthlings and Martians hit it off, sit around for days talking about politics, the weather on Mars and Earth, sports, what really happened with Elvis.Eventually, both the earthlings and Martians feel comfortable enough to work up the nerve and ask the other folks what they're really curious about -- "So how do you guys reproduce?"It's decided to have a demonstration. The Martians go first. Four of them stand on top of each other, make whirring mechanical sounds, lights go off on their foreheads, smoke and bells, and.suddenly, a new Martian pops out.

"Fabulous, just fabulous, love the concept," say the earthlings. Then it's our turn. A suitable volunteer couple has been found, a bed cleared, and the couple goes at it while the Martians stand around taking souvenir photos. The pair finishes in a sweaty heap."Great, that was terrific, very novel," enthuse the Martians, "but one thing.er.where's the new earthling?""Oh, that," they are answered. "That happens nine months from now.

"And the Martians ask, "So why were they in such a rush at the end?"So why are we in such a rush at the end? We animals will swim upstream and leap over dams, will spend hours butting heads with other antlered beasts, will laugh at someone's stupid jokes, all for the chance to mate, to get into that special circumstance where we are in such a rush at the end.What is it that drives us to do so? Is it for the good of the species? Nah -- that style of thinking went out with Marlin Perkins. How about its being for the good of the individual? "By mating as frequently as possible, you maximize the number of copies of your genes in the next generation and thereby enhance your reproductive success in the general population pool." Yeah, right -- how many animals bring evolutionary-biology textbooks to bed with them? Option three: Because itfeelsgood. Of course.What we have here is a dichotomy between the distal and proximal explanations for the same behavior.Distal:the long-term, underlying explanation for why something happened.Proximal:the short-term, nuts-and-bolts explanation.

For example, a female primate gives birth to an infant and, against any sort of logic, exhausts herself caring for it, hauling it around, giving up calories and foraging time, making herself more vulnerable to predators with this cumbersome burden. Why toil away with this maternal behavior? Distal explanation: because among primates, high degrees of maternal investment increase the likelihood of survival of the offspring and thus maximization of passing on copies of genes. Proximal explanation: because something about those big eyes and ears with that wrinkly little face and, I can't stand it, that adorable round forehead, and you justhaveto take care of that kid.Much of behavior is driven by proximal cues, and never is this more the case than when thinking about the motivation for sexual behavior. For behaviors that are that evolutionarily vital, that so often involve risk to life and limb, the motivation can't be abstract and delayed, like the consequences for genetic competition, or for the promise of offspring after a long gestation period (just imagine how few elephants there would be on earth if elephant sex were motivated purely by the cognitive recognition that, do this and, shazzam, two years later some kid pops out). Sexual behavior has to be driven, overwhelmingly, by proximal cues. Animals, including human beings, are interested in sex because it feels good.Now that the Gentle Reader is clear about this fa.