Most of us have probably bought into the folk saying which originated in Victorian times that nature is "red in tooth and claw,” meaning that animals are completely unsentimental, engaged in indiscriminate killing at will. From there, it’s often extrapolated that humans are really no different from our non-human animal cousins. But as with so many of our cultural narratives, what’s widely believed has little basis in science or fact.
Although aggression does serve a variety of evolutionary functions, varying some from species to species, in general (just as with any behavior) it is designed to maximize benefits and minimize costs to fitness. What we see when we look at the actual data is that except in very particular exceptions, most animals exert a lot of restraint when sparring with others of their species. They don’t actually want to kill them most of the time, and may even engage in reconciliatory behaviors after a fight. This applies to both human and non-human animals.
“Destabilization of the social resource network decreases group stability and efficiency and lowers the average fitness benefit derived from cooperation. When group stability is important for individual advantage, selection will favor active peacemaking and cooperation in our closest relatives and ourselves.”
