Natural Selection and the Evolution of Morality in Human Societies

Abstract

Morality is enshrined in cultural codes, such as values, ideologies, and moral norms. These cultural codes would have no teeth, however, unless they could arouse intense emotions. Those behaving improperly must experience guilt and shame if morality is to operate as an effective mechanism of social control, while those observing improper actions must be sufficiently aroused by negative emotions like righteous anger and disappointment that they are willing to incur the costs of imposing negative sanctions on others. Humans are probably the only animal to organize itself through morality, and so, an important question is why and how this moral capacity evolved. Indeed, understanding the evolution of primates in general and apes in particular can help explain why and how the hominin ancestors of humans became more emotional and, in turn, how this emotionality allowed for the development of morality as a primary mechanism of social control in human societies. The story of morality, then, is not so much about the growth of the human neocortex where moral codes are stored as about what evolved in the subcortical areas of the brain, where emotions are generated. Long before the neocortex grew to human proportions, the subcortical areas of the hominid and eventually human brain were rewired to make humans the most emotional and, hence, most (and perhaps only) moral animal on earth.