Just like penguins and other primates, people trade sex for...( ANN ARBOR Mich.---Female penguins ma...),Health

ANN ARBOR, Mich.---Female penguins mate with males who bring them pebbles to build egg nests. Hummingbirds mate to gain access to the most productive flowers guarded by larger males.

New research shows that even affluent college students who don't need resources will still attempt to trade sexual currency for provisions, said Daniel Kruger, research scientist at the University of Michigan School of Public Health.

The exchange of resources for sex---referred to by scientists as nuptial gifts---has occurred throughout history in many species, including humans, Kruger said. 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," Kruger said. "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, Kruger said.

For the study, 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. While the study population was limited to students, these types of exchanges happen all over the world in different cultures and species, he said.

The majority of students were well aware of their own attempts to trade reproductive currency, Kruger said. However,
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