Competition with rivals boosts male testosterone level

Testosterone levels increase when men defeat rivals in competitions, but not after they compete against friends, a new study claims.
A University of Missouri study has found that testosterone levels during group competition are modulated depending on the relationships among the competitors and may be related to the formation of alliances in warfare.
"One interesting thing about humans is that we are the only animal that competes in teams," said Mark Flinn, professor of anthropology at MU.
"Our hormonal reactions while competing are part of how we evolved as a cooperative species. What we found in our study is that although male's testosterone levels increase when men are victorious against strangers or rivals, levels of the hormone tend to stay the same when competing against friends," said Flinn.

Flinn and his research team studied males from varying age groups on the island of Dominica while they played dominoes or cricket.
Flinn found that when males competed against a group outside of their community, their testosterone levels rose during and after competition if they won, but diminished following a defeat.

However, when males competed with their friends, their testosterone levels did not change in response to victory or defeat.
Competing in sport coalitions can raise testosterone levels in males, but males don't have to be competing in order to see a rise in testosterone.
Flinn says that when watching a favourite sport team the viewer is a part of a coalition of fans in the community and can also get a rise in testosterone levels while watching games.

Flinn suggests that coalitions may have had important effects on the evolution of human social psychology.
"The fascinating thing about humans is that whether we are watching or playing the sport, we have the ability to put interactions among the whole team in our heads," Flinn said.
"That just shows how complex our social psychology is. For example, a hockey or basketball player can anticipate how his teammates are going to react when he passes to each one of them and predict the outcome. The ability for humans to be able to do that is pretty astonishing," said Flinn.