The Evolution of the Neurological Basis of Human Sociality

Abstract

Humans are evolved apes, and one of the most distinctive features of contemporary great apes, with whom humans share a good percentage of their genes, is the lack of sociality at the group level. Thus, if the group is the foundation of human societies, as so many claim, it is not a natural unit for an evolved ape like Homo sapiens. There are no bioprogrammers for group formation among humans, as there is for many other mammals that naturally form packs, troops, pods, herds, and other collective formations. Moreover, despite behavioral propensities for some reciprocity, empathy, and even justice calculations among present-day apes, these would have been insufficient for hominins (the ancestors of humans), just as they are for great apes today, to sustain permanent groups. In this chapter, our goal is to outline the route that natural selection took to get around the low-sociality of the last common ancestor to humans and present-day apes. Natural selection significantly rewired the subcortical areas of the hominin brain to make the ancestors of humans successively more emotional; and it is from these new behavioral capacities that humans form social bonds and develop a sense of group solidarity. However, using emotion to form solidarities is a double-edged sword because so many human emotions and, indeed, three-quarters of primary emotions among mammals are negative—thus making human groupings potentially unstable, especially without direct bioprogrammers for group formation wired into the human brain.