I love America. America has made my fortune.

[Flyndaran]

Originally Posted by jason taylor

It is argably biologically necessary, being one of the main reasons humans are not eaten despite being only of moderate strength individually. Few other creatures take revenge. It is only natural for that instinct to continue when dealing with human predators.

Many prey species will stomp to death juvenile predators that are no threat to them now... when the parents aren't looking of course. Revenge is just a bit more common for humans, because we can plan ahead and become far more effective.