Women who avoid one another after a competition may damage their ability to cooperate, according to new research published in Evolution and Human Behavior, but the same isn’t necessarily true for men.

The study, which examined real-life friends, also found that hormonal changes were associated with cooperation between both men and women following a competition.

“I have conducted a lot of research on sex differences in cooperation and competition between same-sex peers. One question that arises is how two friends switch between competing and cooperating,” said study author Joyce Benenson, an associate member of the Department of Human Evolutionary Biology at Harvard University.

“Conflicting self-interests inevitably occur between any two people even if they are invested in one another. Caring for one’s own self-interests and for the relationship are both important. Nevertheless, that means that individuals must be able to resolve conflicts to restore their cooperative relationship.”

“How the switch operates as two individuals go from cooperating with a valued same-sex friend to competing against the friend and back to cooperating is the focus of this research. Here we created a competition in which one friend overwhelmingly beat the other one on a task they both valued,” Benenson.

For their new study, the researchers recruited 81 pairs of same-sex, heterosexual friends for a laboratory experiment.

At first, the two friends sat together at a table and had to work together to complete 25 word problems. Then, the friends competed against each other in a 30-question intelligence test. During the competition, a curtain was drawn down the middle of the table to prevent the participants from interacting with one another.

After this brief competition, the participants had an 8-minute relaxation period. Half of the pairs of friends were randomly assigned to sit side-by-side at the table and to resume talking. The other half remained seated with the curtain drawn between them and were instructed not to communicate with one another.

Finally, the friends once again worked together to complete a second set of word problems.

Throughout the experiment, the researchers collected saliva samples from the participants, which were used to assess changes in the hormone cortisol.

Benenson told PsyPost the study has two main findings: “First, female friends who compete need to come together right away and focus on something they both benefit from. Avoiding one another damages their later ability to cooperate. In this study, those women who were separated for 8 minutes following a competition lost their ability to cooperate on a simple task.”

“Those women who were placed in immediate contact following the competition greatly improved their ability to cooperate. Men’s friendships were not affected by whether they were in immediate contact or not following the competition.”

“Second, hormonal changes underlie these switches. In this study, when friends made contact immediately following the competition, cortisol increases in the winner of the competition allowed the two friends to better cooperate. This occurred for both sexes. In other words, the more the winner is concerned and invested in the friendship, the more the two friends can return to cooperating,” Benenson said.

But the research leaves some questions unanswered

“We don’t know what it is that the winners do that allows a pair of friends to renew their cooperative efforts. We also don’t know whether women will return to normal baseline levels of friendship after being able to cooperate. A number of my studies have shown that girls and women experience more difficulty than boys and men renewing friendships following competition or any conflict,” Benenson explained.

In previous research, Benenson and her colleagues analyzed tennis, table tennis, badminton, and boxing matches from 44 countries. They found that men were far more likely to engage in friendly physical contact — such as handshakes, back pats and even hugs — after the game had ended.

“Women in particular need to learn how to compete with one another honestly and feel confident they can maintain the relationship. Men have an easier time competing against friends and reconciling afterwards,” Benenson said.

“One thing men do is give one another friendly touches before and after a competition. Women don’t do this as much. Friendly physical contact may be a strong signal that the individual intends to maintain the relationship no matter the outcome.”

The study, “Social contact and hormonal changes predict post-conflict cooperation between friends“, was authored by Joyce F. Benenson, Lindsay J. Hillyer, Maxwell M. White, Sera Kantor, Melissa Emery Thompson, Henry Markovits, and Richard W. Wrangham.