Like human families, for monkeys and apes, the day-to-day business of living in a group inevitably brings quarrels. ᴅɪsᴘᴜᴛᴇs could be over who gets the shady spot to rest in, who’s in charge, who to groom, who to mate with, who to huddle up with in the cold or where to feed. Life can be ʜᴀʀsʜ. But luckily, primates have a whole ᴀʀsᴇɴᴀʟ of strategies up their sleeves to forestall, or mitigate the costs of, ᴀɢɢʀᴇssɪon.
These range from formal submission and calming tensions before they escalate, to mediation and policing interventions during a ᴄᴏɴғʟɪᴄᴛ. But if ᴀɢɢʀᴇssɪon is unavoidable and a ꜰɪɢʜᴛ occurs, opponents have another option. Because just like humans, primates can also repair their relationship through reconciliation – to help reestablish friendly contact.
Studies have found that reconciliation has emotional consequences in primates, reducing indicators of disᴛʀᴇss and anxiety – such as elevated heart rate and scratching – back to baseline levels.
Reconciliatory behaviour was first recognised by Frans de Waal in the 1970’s in a seminal study of post-ᴄᴏɴғʟɪᴄᴛ behaviour in chimpanzees. On the surface, reconciliation boils down to friendly contact between opponents soon after a ꜰɪɢʜᴛ but it also seems to do more than just end the ᴄᴏɴғʟɪᴄᴛ.
Post-ᴄᴏɴғʟɪᴄᴛ anxiety levels in primates have also been found to be related to the quality of the relationship between the former opponents. Among humans, this makes perfect sense, if you argue with a close friend, you’re much more sᴛʀᴇssed than if you’ve argued with a passing acquaintance.
Researchers have also found that reconciliation reduces the likelihood of renewed ᴀɢɢʀᴇssɪon. But perhaps most importantly, reconciliation appears to restore tolerance and cooperation between friends.
While it’s well known that adult chimpanzees are more likely to reconcile with their more valuable friends than non-friends, the young chimpanzees didn’t seem to make this discrimination yet, suggesting they’ve still got a lot to learn.
In fact, reconciliation is common to many social species shows how deep-rooted our own tendency is for peace-making. But it would seem that some techniques are actually learned rather than innately acquired.
In an innovative experiment some years ago, de Waal showed that the reconciliatory behaviour of ǫᴜᴀʀʀᴇʟsᴏᴍᴇ, juvenile rhesus macaques, could be increased threefold after a few months of co-housing with more easygoing, peacemaking stumptail macaques.
So conciliatory tendency seems to be a social skill that is acquired through juvenile experience, rather than an innate behaviour. And a study just published in the International Journal of Primatology by one of my PhD students, supports this view.