A New Evolutionary Perspective The Nomadic Forager Model
I want to bunt eland, kudu, and gemsbok, but bunting men is what gets you killed. —JU/'HOANSI MAN, QUOTED BY RICHARD LEE IN THE IKUNG SAN
What are the evolutionary costs and benefits of aggressive behavior? Some likely costs include being injured, getting killed, harming relatives if fighting with them, losing friends, taking time and energy away from other necessary pursuits such as finding food or mating, and, among humans, getting yourself expelled from the group.1 A central point is that engaging in aggression can be dangerous and has the potential for reducing an individual's fitness in various ways.2 Animals sometimes die as a result of injuries sustained in fights, as observed, for instance, among hyenas, lions, and various primates, but as ethologist Robert Hinde assesses, "death and injury are less common than might be expected." Aggression researchers Caroline and Robert Blanchard explain: "In evolutionary terms . . . successful individuals will be those with techniques which enable them to avoid agonistic situations involving serious possibilities of defeat or injury, while leaving them to continue in more promising situations."3
Evolutionary benefits of aggression include, depending on species and circumstances, obtaining food, territory, or mates, protecting oneself and one's offspring and other relatives from injury or death, and gaining dominance and hence better access to resources or mates. Thus aggression seems to have various evolutionary functions. Furthermore, the severity, frequency, and specific functions of aggressive behavior vary from species to species. For instance, some species engage in territorial defense whereas others do not, and some species fight primarily during mating season whereas others are aggressive in other contexts.4
The essential point is that although aggression can be risky, clearly it can be beneficial to individual fitness in certain circumstances. Theoretically speaking, we would expect that natural selection, operating over many generations, has shaped the aggressive behavior engaged in by the members of a given species, including humans, so as to maximize fitness benefits and minimize fitness costs under conditions of the ancestral evolutionary environment.
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