Researchers discovered that adult males' testosterone levels dropped when
they interacted with the wife of a close friend, and said this may be an
evolutionary adaptation that helped humans live in large groups.
"Although men have many chances to pursue a friend's mate, propositions for
adultery are relatively rare on a per-opportunity basis," Mark Flinn, a
professor of anthropology at the University of Missouri, said in a university
"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," he explained.
What the findings mean
The results from adult and adolescent males in a rural Dominican community,
published in the journal Human Nature, may help explain how people
manage to cooperate in neighbourhoods, cities and even worldwide, the
"Ultimately, our findings about testosterone levels illuminate how people
have evolved to form alliances," Flinn said. "Using that biological
understanding of human nature, we can look for ways to solve global problems.
The same physiological mechanisms that allow villages of families to coexist and
cooperate can also allow groups like NATO and the UN to coordinate efforts to
solve common problems." One example would be the threat of climate change, he
During evolution, men who constantly betrayed their friends' trust and
endangered the stability of families may have caused a survival disadvantage for
entire communities, Flinn suggested. The lack of trust in these communities
would have made them fragile and vulnerable to attack and conquest.
The American Association for Marriage and Family Therapy
explains the causes and effects of infidelity.
(Picture: condoms on clothesline from Shutterstock)