揭祕人類“性交易”的進化淵源
Cost of coitus: Male monkeys pay for sex
Selling sex is said to be humankind's oldest profession but it may have deep evolutionary roots, according to a study.
Selling sex is said to be humankind's oldest profession but it may have deep evolutionary roots, according to a study into our primate cousins which found that male macaques pay for intercourse by using grooming as a currency.
Michael Gumert of Nanyang Technological University in Singapore made the discovery in a 20-month investigation into 50 long-tailed macaques in Kalimantan Tengah, Indonesia, New Scientist reports on Saturday.
On average, females had sex 1.5 times per hour.
But this rate jumped to 3.5 times per hour immediately after the female had been groomed by a male -- and her partner of choice was likely to be the hunky monkey that did the grooming.
Market forces also acted on the value of the transaction.
If there were several females in the area, the cost of buying sex would drop dramatically -- a male could "buy" a female for just eight minutes of nit-picking.
But if there were no females around, he would have to groom for up to 16 minutes before sex was offered.
The work supports the theory that biological market forces can explain social behaviour, the British weekly says.
"There is a mix of economic and mating markets in the human species itself," said Ronald Noe of France's University of Strasbourg.
"There are many examples of rich old men getting young attractive ladies."
性交易”據說是人類最早的職業，而一項研究表明，這可能具有很深的進化淵源。該項對人類親緣的研究發現，雄性獼猴會通過給雌性獼猴梳理毛髮的手段來換取交配機會。這種手段好比人類使用的貨幣。
據《新科學家》週刊上週六報道，新加坡南洋理工大學的麥克爾•古莫爾特通過對印度尼西亞加裏曼丹地區的50只長尾獼猴進行爲期20個月的研究，得出以上結論。
研究發現，雌性獼猴的交配頻率爲平均每小時1.5次。
但在一隻雄猴給她梳理完毛髮後，這一頻率會立刻提高至每小時3.5次。此外，雌猴很可能會選擇爲她梳理毛髮的那隻雄猴作爲自己的“性伴侶”。
此外，市場力量也會影響交易價格。
如果某一區域內有幾隻雌猴，那麼“性交易”的價格會大大下跌，一隻雄猴只需爲一隻雌猴抓蝨八分鐘就能“換取”交配機會。
但在周圍沒有雌猴的情況下，他得付出16分鐘的努力。
英國《新科學家》週刊稱，該研究爲“生物市場力量可以解釋社會行爲”的理論提供了支持。
法國斯特拉斯堡大學的羅納爾德•諾伊說：“人類物種自身存在着一種經濟市場與交配市場的結合。”
“當今社會不乏有錢的老男人與年輕貌美的女人結合的實例。”
