Classic case of “no free lunch,” a new paper in Science, Did Warfare Among Ancestral Hunter-Gatherers Affect the Evolution of Human Social Behaviors?, gives rise to popular press pieces with titles such as Blood and treasure and Altruism’s Bloody Roots. If for most of human existence our species has been trapped by the reality of Malthusian conditions, boxed in by fixed resources, then it stands to reason that ingroup altruism and cohesion must be balanced by more vicious between group competition. This sort of process is not necessarily most obvious biologically. Rather, consider the cultural exemplar of religion. There are many religious groups which exhibit enormous within group altruism, but can turn viciously and without fellow human feeling against outgroups. The rather unappetizing reality of groups cannibalizing each other is likely why the white nationalist psychologist Kevin MacDonald uses group selection theory as his preferred model to explain how Jews manipulate and control Northern Europeans to advance their own interests.
No one said reality was going to be peaches & cream.