I investigate why animals differ in their social behaviour. I classify the extent of cooperation and competition between individuals in a wide range of populations and identify which environmental conditions lead to certain behaviours. I started my comparative work during my PhD in the Department of Primatology at the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany). During my postdoc at the University of Cambridge (UK), I worked on resolving the causes and consequences of the evolution of different types of sociality across all mammals. I recently joined the Department of Human Behavior, Ecology and Culture, back at the MPI EVA in Leipzig, where I am identifying the extent of the ecological basis for variation in human behavior.