Washington, Apr 11 : Researchers at the University of Michigan have shown that humans follow in the footsteps of penguins and other primates, when it comes to trading sex for resources.
Studies have shown that female penguins mate with males who bring them pebbles to build egg nests. Even hummingbirds mate to gain access to the most productive flowers guarded by larger males.
And now according to the study, affluent college students, who don't need resources, attempt to trade sexual currency for provisions.
Daniel Kruger, research scientist at the University of Michigan School of Public Health and study's lead author said that the so-called "nuptial gifts" - the exchange of resources for sex - 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.
However, the recent findings suggest that such behaviors are hard wired, and persist no matter how much wealth, resources or security that people obtain.
"It's remarkable to find these patterns in the students in the study. 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," Kruger said.
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, Kruger said.
In the study, the researchers interviewed 475 U-M undergraduate students to discover if they attempted exchanges in reproductively relevant currencies outside of dating or formally committed relationships, and if they were aware of attempts others tried with them.
Some of the attempted trades included: tickets to the U-M versus Ohio State game; studying assistance; laundry washed; a designer bag; and voice lessons among other things.
Students in the study were 18-26 years old. For exchange attempts made, 27 percent of men and 14 percent of women reported attempts to trade investment for sex, 5 percent of men and 9 percent of women reported attempts to trade sex for investment.
Of exchange attempts initiated by others, 14 percent of men and 20 percent of women reported that someone else attempted to trade investment for sex with them, and 8 percent of men and 5 percent of women reported that someone else attempted to trade sex for their investment.
A sample of older individuals, especially one that is more representative of the general population, would likely report higher frequencies of experiences, Kruger said. The assumption is an older population would have more unmet needs and would be more sexually active.
"The confirmation of hypothetical predictions regarding these exchanges once again demonstrates the power of an evolutionary framework for understanding human psychology and behavior," Kruger said.
The study 'Young Adults Attempt Exchanges in Reproductively Relevant Currencies' is published in the Journal of Evolutionary Psychology.