Dynamics of alliance formation and the egalitarian revolution

TL;DR

This paper presents a stochastic model explaining how human societies transitioned from hierarchical to egalitarian structures through alliance formation, driven by cognitive and social factors, leading to stable group-wide egalitarian norms.

Contribution

It introduces a novel model showing how alliances emerge rapidly in groups, facilitating the shift to egalitarian societies in human evolution.

Findings

Alliances emerge via phase transition-like processes under certain social conditions.

Cultural inheritance can lead to a single, stable egalitarian alliance across generations.

Increased cognitive abilities may trigger rapid societal shifts from hierarchy to egalitarianism.

Abstract

Arguably the most influential force in human history is the formation of social coalitions and alliances (i.e., long-lasting coalitions) and their impact on individual power. In most great ape species, coalitions occur at individual and group levels and among both kin and non-kin. Nonetheless, ape societies remain essentially hierarchical, and coalitions rarely weaken social inequality. In contrast, human hunter-gatherers show a remarkable tendency to egalitarianism, and human coalitions and alliances occur not only among individuals and groups, but also among groups of groups. Here, we develop a stochastic model describing the emergence of networks of allies resulting from within-group competition for status or mates between individuals utilizing dyadic information. The model shows that alliances often emerge in a phase transition-like fashion if the group size, awareness, aggressiveness, and persuasiveness of individuals are large and the decay rate of individual affinities is small. With cultural inheritance of social networks, a single leveling alliance including all group members can emerge in several generations. Our results suggest that a rapid transition from a hierarchical society of great apes to an egalitarian society of hunter-gatherers (often referred to as "egalitarian revolution") could indeed follow an increase in human cognitive abilities. The establishment of stable group-wide egalitarian alliances creates conditions promoting the origin of cultural norms favoring the group interests over those of individuals.