This kind of a behaviour is often seen in humans when they come across disputes.
As part of the study, Arianna De Marco at the University of Florence, Italy, and colleagues saw this behaviour among Tonkean macaques as they observed two captive groups over seven months.
When a macaque behaved aggressively - by chasing, grabbing or biting, for instance - De Marco chose a bystander at random and recorded whether it would "affiliate" with another macaque within 5 minutes of the conflict ending.
The primates were considered to be affiliating if they sat near, groomed or played with another bystander, reports New Scientist.
For comparison, De Marco observed the same macaque for 5 minutes the next day at approximately the same time.
The researchers discovered that bystanders were more likely to affiliate with another bystander after conflicts than at peaceful times. In one group, the macaques were almost three times as likely to do so, and in the other group almost seven times as likely.
After witnessing a conflict, bystander macaques tend to appear unusually agitated, scratching themselves more than normal, for instance. Once the macaques affiliated with each other, however, they seemed to calm down. (ANI)