Sublime

In the 1930s, Max Kleiber, a Swiss agricultural biologist, observed that, across mammal species, from shrews to elephants, the energy required to maintain basic metabolic function is closely correlated with an organism’s body size.

Tomasello believes that human ultrasociality arose in two steps. The first was the ability to share intentions in groups of two or three people who were actively hunting or foraging together. (That was the Rubicon.) Then, after several hundred thousand years of evolution for better sharing and collaboration as nomadic hunter-gatherers, more collabo

The usual rules of sex roles, then, are ones of male display and female choosiness. This stems from that long-ago difference in investment between the sexes—the large resource-rich egg and the small streamlined sperm.

I described three common ways in which people flip the hive switch: awe in nature, Durkheimian drugs, and raves. I described recent findings about oxytocin and mirror neurons that suggest that they are the stuff of which the hive switch is made. Oxytocin bonds people to their groups, not to all of humanity. Mirror neurons help people empathize with

promiscuity tends to break down into polygyny as powerful men discover that they are in a position to demand exclusivity from multiple reproductive partners, either in sequence or in tandem.