Gilbert Roberts

I am a behavioural ecologist / evolutionary psychologist working on the evolution of cooperation in the Centre for Behaviour & Evolution at Newcastle University.

Cooperative behaviour is fundamental to human societies and is found in many other animals yet it presents a fascinating challenge to biologists and psychologists alike. My research focuses on trying to explain how cooperation works and why humans are such a cooperative species. I take a cross-discipline approach combining theoretical and modelling work with fieldwork and experiments on humans and other animals. Two theories I have been developing and testing revolve around the roles of reputations and of interdependence.

A concern for reputation is a distinctive feature of human cooperation: we are more cooperative when we are observed and we favour those who cooperate. The idea behind my theory of Competitive Altruism (actually better referred to as competitive cooperation) is that by cooperating we may be investing in a reputation which brings us longer term benefits. Research in my group provided the first experimental evidence for competitive altruism: people tend to be more cooperative when their behaviour is public and they have an opportunity to choose partners. This finding has since been replicated by other authors.

We have also recently demonstrated that reputation building pays through access to more profitable partnerships. Competitive altruism provides a more generally applicable theory of reputation-based cooperation than indirect reciprocity. We have also provided the first evidence for competitive altruism in a mate choice context: people are more cooperative with more attractive members of the opposite sex, and cooperating makes you more attractive.

A key problem in explaining cooperation is that while cooperation may pay well, exploiting a cooperator may pay even better. However, I argue that interdependence is an important factor facilitating cooperation because cooperators benefit as a by-product of helping their recipients. Helping can then be favoured when its costs are outweighed by the altruist’s stake in the recipient’s benefits. I have shown how defining an individual’s ‘stake’ in another corresponds to Hamilton’s rule. The direct benefits of cooperation, even when there is no reciprocation, are now being seen as increasingly important.