We are deeply wired for sex trade

Apr 11, 2008 18:06 GMT  ·  By

In mating rituals of many birds, the male has to offer a food item (like a fish in kingfishers, an insect in the case of bee-eaters or a fruit in the case of hornbills) or a nest building material item (stones in penguins). Hummingbird females mate in order to receive permission for the most productive flowers guarded by larger males. Foxes too can offer food to the males during courtship. In mammals, chimps are known to offer food for sex: a 2007 research carried on in the Republic of Guinea (western Africa) showed that male chimps offered females papaya fruits, stolen from plantations, for sexual favors. But this is not an animal thing: a new research published in the "Journal of Evolutionary Psychology" and led by Daniel Kruger, research scientist at the University of Michigan, School of Public Health, shows that sexual currency is deeply wired in our brains.

"The exchange of resources for sex - referred to by scientists as nuptial gifts - has occurred throughout history in many species, including humans. The male of the species offers protection and resources to the female and offspring in exchange for reproductive rights. For example, an arranged marriage can be considered a contract to trade resources," said Kruger.

The new research shows that this behavioral pattern is so deeply embedded in our minds, that it is still present when external resources or security do not represent a necessity.

"We have seen many examples where people do this out of necessity, but we still see these tendencies in people who are already well provided for. In addition, there are predictable, sexual differences in the types of exchanges attempted. Men are more likely to attempt to exchange investment for sex, females were more likely to attempt to exchange sex for investment," said Kruger.

The study was made on 475 undergraduate students, aged 18 to 26, and focused on attempted sexual trade outside of dating or committed relationships. "These types of exchanges happen all over the world in different cultures and species. The majority of students were well aware of their own attempts to trade reproductive currency. However, if they were in committed relationships, they did not view the partnership as trading in reproductive currencies," said Kruger.

Investment for sex appeared to succeed in about 25% of the cases. Benefits offered for sex (amongst others) were tickets to the U-M versus Ohio State game; studying assistance; laundry washed; a Louis Vuitton bag; voice lessons. 27% of men and 14% of women attempted to exchange resources for sex, while 5% of men and 9% of women exchanged sex for resources. 14% of men and 20% of women had been offered resources for sex, and 8% of men and 5% of women were offered sex for their resource.

"A sample of older individuals, especially one that is more representative of the general population, would likely report higher frequencies of experiences," said Kruger, pointing that sexual necessity and activity is higher in that category. "The findings are remarkable in that any exchanges were reported at all, considering the subjects' youth and affluence - in other words, they don't want for much yet they still attempt these exchanges," he added.