The evolution of war and peace in animal societies

The evolution of cooperation is one of the great puzzles of biology and lies at the heart of current attempts to understand the evolution of complex life, from teams of replicating molecules through to cooperative animal societies. One major theory is that sufficiently intense conflict between groups can promote cooperation and altruism within them. In humans, cooperation may have arisen as a consequence of intense warfare among our prehistoric ancestors, a pattern also proposed to explain cooperation in animal societies as diverse as ants and chimpanzees. Yet nature also shows us that cooperation and peace between distinct groups is possible, both in biological systems (as seen in peaceful bonobos, social amoeba, and between maternal and paternal genes in a fertilized egg) and in small-scale human societies, via trade and technological exchange. An outstanding challenge is to identify the factors that explain these varied patterns of conflict and cooperation between groups, each comprised of individuals with different interests and incentives. I will use a uniquely suited termite species, in which colonies engage in both fatal combat and peaceful fusion, to uncover the factors that drive the evolution of war and those that promote peace.

Combining carefully controlled experiments in the lab with observations of natural termite colonies in the wild, I will perform the first test of hypotheses proposed to explain patterns of war and peace in humans and other animals. First, I will determine the causes of intergroup conflict and colony fusion by testing how (i) wealth and inequality, (ii) the potential for trade, and (iii) a common enemy, shift colonies between conflict and peace. Second, I will establish the consequences of fighting and fusing for individual behaviour and success, and colony productivity. Finally, I will develop new theory that unites my experimental findings and allows me to explore the effect of these factors acting together, generating general predictions that are testable across a range of species.

Intergroup conflict and cooperation are of great biological and human interest, given our own evolutionary history of warfare and cooperation. The combination of theory and experiments at the heart of my project has interdisciplinary relevance beyond biology, particularly in the fields of psychology, economics, sociology, and political science. My research will provide fundamental insights into the forces that suppress conflict and promote cooperation between groups. These insights will be the first step to establishing if peaceful relationships and social integration at the group level can facilitate the evolution of increased social complexity.