Early hominins and the reversal of dominance hierarchy

Abstract

Sometime between our last common ancestor with chimpanzees and today, our hominin ancestors transitioned from bully-dominated dominance hierarchy to reversed dominance hierarchy in which bullies were actively suppressed. This paper presents an evolutionary analysis of this transition to identify its causes and possible timing. The analysis shows that the transition requires a sufficiently low fitness cost of helping in bully-suppressing coalitions and a just-right amount of drift, and that the transition goes through a highly violent phase before its completion. An examination of different forms of early-hominin bullying suggests that the transition did not occur during the Miocene Epoch, should have occurred by the time of Homo erectus, but could have occurred earlier, possibly in the Pliocene before the emergence of Homo.