June 20, 2013
Evolutionary biologists often talk like economists, particularly when the topic is cooperation. Instead of dollars, euros, or pounds, the universal currency in evolution is fitness. A species that cooperates cannot survive when competing against a non-cooperative opponent unless the fitness benefits provided by cooperation, such as those resulting from greater access to resources, outweigh the costs. To make matters more complicated, cooperative benefits often take the form of "public goods," which benefit all nearby individuals, whether cooperator or not. This sets the stage for the emergence of "cheaters", which exploit the cooperation of others without contributing themselves. Despite cooperation seeming at odds with the notion of "survival of the fittest", we now have a good understanding of how cooperation can persist in the face of cheaters based on the tremendous work of Fischer, Haldane, Hamilton, Price, and those who have since followed. When the costs and benefits are favorable, and when close relatives are more likely to receive those benefits, cooperation can survive and even thrive.