I have always been fascinated by how animals organise their social life. Most social interactions are characterised by peaceful cooperation, for instance, by helping others. However, such behaviours pose a substantial challenge to the theory of natural selection because evolution should favour those that outcompete and not those that help others. In addition, we understand very little about the psychological prerequisites of cooperation. This is why I study the evolutionary and psychological origins of social interactions. Most of my studies are based on predictions derived from game theoretical models that I test mainly experimentally both in the lab and field. Besides, I have always been interested in welfare and conservation issues.