RT Journal Article
SR Electronic
T1 The Size of the Stag Determines the Level of Cooperation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.02.19.432029
DO 10.1101/2021.02.19.432029
A1 Schnell, Eric
A1 Schimmelpfennig, Robin
A1 Muthukrishna, Michael
YR 2021
UL http://biorxiv.org/content/early/2021/02/20/2021.02.19.432029.1.abstract
AB In the last 12,000 years, human societies have scaled up from small bands to large states of millions and even billions. Many modern societies and even groups of societies cooperate on large-scale projects with relatively low levels of conflict, but the scale and intensity of cooperation varies dramatically between societies. Here we attempt to formalize dynamics that may be driving this rapid increase in cooperation and the differences we see between societies. Our model extends an N-person stag hunt to include population growth dynamics, “stags” with different sized payoffs, and competition for these stags. An increasing number of cooperators is required to access larger stags. The payoff from these stags in turn increases carrying capacity, which increases competition for the stag. As population size increases, new cooperative thresholds are attainable, and as population size shrinks, previously attainable thresholds fall out of reach. Among other predictions, we show that when a new threshold is accessible to a population, the level of cooperation will increase to reach this threshold. However, when the next threshold is out of reach, cooperation decreases as individuals refrain from costly cooperation, preferring a smaller stag. This model offers a framework for understanding the rapid increase in the scale of human cooperation and decline of violence, differences between societies, and challenges to future cooperation.Competing Interest StatementThe authors have declared no competing interest.