A study by scholars at the University of Missouri concludes that evolution may have played a role in men having a natural aversion to adultery with their friends’ wives. The study found that males’ testosterone levels drop when they are interacting with the wife of a close friend.
The study’s authors state that men who were constantly betraying their friends trust by having adulterous relationships with their wives may have caused a survival disadvantage for their entire communities. A community of men who didn’t trust each other would be vulnerable to attack, conquest, and annihilation. Thus, on an evolutionary basis, men who were less likely to lust after their friends’ wives may have been more likely to survive and produce offspring.
Mark Flinn, professor of anthropology in the College of Arts and Science and a co-author of the study, stated, “Men’s testosterone levels generally increase when they are interacting with a potential sexual partner or an enemy’s mate. However, our findings suggest that men’s minds have evolved to foster a situation where the stable pair bonds of friends are respected. Ultimately, our findings about testosterone levels illuminate how people have evolved to form alliances.”
The study, “Hormonal Mechanisms for Regulation of Aggression in Human Conditions,” was published in the March 2013 edition of the journal Human Nature.