World's oldest profession

Apparently both paying for sex and prices that respond to market forces go way back in our evolutionary heritage.

TIME MAGAZINE - In a recent study of macaque monkeys in Indonesia, researchers found that male primates "paid" for sexual access to females — and that the going rate for such access dwindled as the number of available females went up....

Researchers, who studied the monkeys for some 20 months, found that males offered their payment up-front, as a kind of pre-sex ritual. It worked. After the females were groomed by male partners, female sexual activity more than doubled, from an average of 1.5 times an hour to 3.5 times. The study also showed that the number of minutes that males spent grooming hinged on the number of females available at the time: The better a male's odds of getting lucky, the less nit-picking time the females received.

And whether you're one of the cool kids matters too, lead researcher Michael Gumert told Discovery News:

"Powerful individuals can take more and give less than low-ranked individuals can," he said, suggesting that such corruption of the fair trade ideal appears to be an inherent facet of primate social life that can apply to everything from monkey sex to human politics. High-ranking females can also skew the system because, in the case of macaques, they demand more attention before they agree to mate.

(Photo by researcher Michael Gumert from Discovery News.)