Person:

Agren, Jon

Cooperation occurs at all levels of life, from genomes, complex cells and multicellular organisms to societies and mutualisms between species. A major question for evolutionary biology is what these diverse systems have in common. Here, we review the full breadth of cooperative systems and find that they frequently rely on enforcement mechanisms that suppress selfish behaviour. We discuss many examples, including the suppression of transposable elements, uniparental inheritance of mitochondria and plastids, anti-cancer mechanisms, reciprocation and punishment in humans and other vertebrates, policing in eusocial insects and partner choice in mutualisms between species. To address a lack of accompanying theory, we develop a series of evolutionary models that show that the enforcement of cooperation is widely predicted. We argue that enforcement is an underappreciated, and often critical, ingredient for cooperation across all scales of biological organization.

While Engelhardt and Taborsky1 agree with the core argument of our recent article2—that enforcement is central to the evolution of cooperation—they go on to suggest i) that our use of the word “enforcement” is semantically problematic and ii) that we neglect to distinguish between behavioural manipulations that occur via helping or harming. We find no merit in these points.