[Kryptid (OP)]

So we all know what revenge is. Someone makes you angry so you do something to get back at them. However, surely this behavioral pattern must have some beneficial effect or it wouldn't be so common? If you watch even little children, they will hit a child back that hit them first. It appears to be an innate desire.

I think most of us are aware of how evolution works. If a given trait improves your chances of producing viable offspring, it will be selected for. I'm not sure how a vengeful personality would necessarily increase your chances of finding a mate.

One might could also argue that a trait would be selected for if it decreases your competition's chances of producing viable offspring (since their offspring might compete with your own offspring). However, revenge only very rarely goes so far as to kill or (or castrate!) the person of your ire, so they should still be quite capable of reproducing after you've had your vengeance.

I had a possible theory. Very often revenge involves physical violence (at least with men), so perhaps beating up your rival makes them less likely to challenge you in the future. If you think about a group of primitive humans with a dominance hierarchy, one male besting another male in physical combat may move them up in social rank. Higher social status = more likely to get a mate. However, this happens often in the wild even when rivals haven't done anything directly to their aggressor. One male enters another male's territory and "boom" a fight can start.

Unfortunately, I'm not sure that theory can explain some other aspects of revenge. Sometimes it DOESN'T involve violence. You might just key their car or put laxative in their drink. Those things wouldn't necessarily affect their social status/ability to produce offspring.

Do animals desire revenge?