Evolutionary precursors of social norms in chimpanzees: a new approach

Moral behaviour, based on social norms, is commonly regarded as a hallmark of humans. Hitherto, humans are perceived to be the only species possessing social norms and to engage in moral behaviour. There is anecdotal evidence suggesting their presence in chimpanzees, but systematic studies are lacking. Here, we examine the evolution of human social norms and their underlying psychological mechanisms. For this, we distinguish between conventions, cultural social norms and universal social norms. We aim at exploring whether chimpanzees possess evolutionary precursors of universal social norms seen in humans. Chimpanzees exhibit important preconditions for their presence and enforcement: tolerant societies, well-developed social-cognitive skills and empathetic competence. Here, we develop a theoretical framework for recognizing different functional levels of social norms and distinguish them from mere statistical behavioural regularities. Quasi social norms are found where animals behave functionally moral without having moral emotions. In proto social norms, moral emotions might be present but cannot be collectivized due to the absence of a uniquely human psychological trait, i.e. shared intentionality. Human social norms, whether they are universal or cultural, involve moral emotions and are collectivized. We will discuss behaviours in chimpanzees that represent potential evolutionary precursors of human universal social norms, with special focus on social interactions involving infants. We argue that chimpanzee infants occupy a special status within their communities and propose that tolerance towards them might represent a proto social norm. Finally, we discuss possible ways to test this theoretical framework

The Evolution of Social Norms

Social norms are patterns of behavior that are self-enforcing at the group level: everyone wants to conform when they expect everyone else to conform. There are multiple mechanisms that sustain social norms, including a desire to coordinate, fear of being sanctioned, signaling membership in the group, or simply following the lead of others. This article shows how stochastic evolutionary game theory can be used to study the dynamics of norms. We illustrate with a variety of examples drawn from economics, sociology, demography, and political science. These include bargaining norms, norms governing the terms of contracts, norms of retirement, duelling, footbinding, medical treatment, and the use of contraceptives. These cases highlight the challenges of applying the theory to empirical cases. They also show that the modern theory of norm dynamics yields insights and predictions that go beyond conventional equilibrium analysis