Institute of Ecology and Evolution

Evolution of cooperation

Vampirebat in flight
Vampirebat in flight © Uwe Schmidt, Wikimedia Commons

The evolution of cooperation remains a central paradox in biology. As Charles Darwin remarked in ‘On the Origin of Species’, “Natural selection will never produce in a being anything injurious to itself, for natural selection acts solely by and for the good of each”. An operation harming the actor at the benefit of someone else cannot be easily explained by the theory of natural selection. Ten years ago, the 125th anniversary issue of the journal Science identified the question of ‘how did cooperative behaviour evolve?’ as one of the top 25 challenges scientists would be facing over the next quarter-century.

Blood donation graphics
Vampire bats donate blood that they have collected preferentially to social partners that donated blood to them before or that had groomed them before. Genetic relatedness between donor and receiver is comparatively of weak importance. Experimental results by G.G. Carter and G.S. Wilkinson, highlighted by Michael Taborsky, «Social Evolution: Reciprocity There Is», Current Biology Vol 23 No 11, 2013.

It is about time to appraise what this last decade of research on this subject has unveiled. The present theme issue on ‘The evolution of cooperation based on direct fitness benefits’ combines 18 articles that are closely linked by a common question: what mechanisms promote cooperation between unrelated individuals, and how is such cooperation evolutionarily stable? This question has received increased attention in the recent past, driven by new empirical data as well as by novel theoretical and conceptual approaches. Empirically, there is a growing realization that the direct fitness benefits of cooperation must be quantified as carefully as kin-selected benefits have been in the past. Behavioural mechanisms like reciprocity and negotiation are increasingly subject to close experimental scrutiny, and theoreticians are now building more complex and realistic models to understand cooperation in larger, multi-level societies.

This theme issue is structured in three main parts focusing on the evolution of cooperation based on direct fitness benefits at the levels of (i) theoretical models, (ii) animal societies and (iii) humans. The contributions to this theme issue portray the state of the art in this field by synthesizing our current understanding of cooperation between non-kin, and by pointing out problems that are still outstanding.

Rabbitfishes in Australia's Great Barrier Reef

Rabbitfishes in Australia's Great Barrier Reef

Rabbitfishes in Australia's Great Barrier Reef take turns in standing sentinel, so that each one in turn can concentrate on foraging. Foragers will eventually take over the sentinel role, so that a 'win-win' situation results - the fitness effects of their behaviour are similarly correlated to each other as they would be among relatives. © Jordan M. Casey, Picture from Simon J. Brandl & David R. Bellwood, «Coordinated vigilance provides evidence for direct reciprocity in coral reef fishes», Scientific Reports, 5:14556.