Behave: The Biology of Humans at Our Best and Worst

Trivers noted that evolution could create altruists in a species where individuals could remember their prior interactions with other individuals and then limit their current niceness to those who were likely to repay the favor. We humans are obviously just such a species. Trivers proposed that we evolved a set of moral emotions that make us play “

Natural selection has made us a cultural species by altering our development in ways that (1) slowed the growth of our bodies through a shortened infancy and extended childhood but added a growth spurt in adolescence, and (2) altered neurological development in complex ways that make our brain advanced at birth yet both highly expandable and enduri

Like some insect societies, but unlike other great apes, Homo sapiens became eusocial, or highly social. At the same time, in-group sociality was matched by aggression toward out-groups. Cooperation within the group was forged by war between groups.