The Difficulty of Cooperation
Once established, cooperation is an enormously potent adaptation. Technological specialization and the advantages that the law of comparative advantage bestows on trade generate great benefits. Specialization and trade probably presuppose an established environment of cooperation. But even cooperation in defense, hunting, and foraging gives access to a far broader range of resources than any individual hominid could access. Cooperation both increases the fraction of local resources harvested and buffers the effects of variation in any one resource, and it ameliorates many dangers to which primate flesh is heir. Once established, then, cooperation will transform both the ecological and the social environment. In turn, among intelligent social animals cooperation leads to profound cognitive transformations by changing the mix of problems faced by agents.
But cooperation is a difficult adaptation – it i not within the space of evolutionary possibility for most lineages, for reasons made vivid by the Prisoner’s Dilemma. For most animal species, the Temptation to Defect subverts cooperation. Male langurs attempt to kill the dependent young of females in bands which they take over. Yet, despite the fact that each female would be protected in a solid coalition, they do not mobilize collectively against such males. If they cooperated in defense, wildebeest would have little to fear from African hunting dogs. But in both cases, and in many others, the free-rider would be fitter still. Though everyone is better off in a cooperating rather than a defecting group, a defector in a predominantly cooperative environment is better off still. Defection is often disruptive, reducing everyone’s absolute fitness. Yet without some countervailing evolutionary mechanism, selection can allow disruptive behavior to invade. Thus, if aggressive males who expropriated the foraging resources of women were more fit than males who respected their property rights, without a countervailing force that behavior would spread in a population. It would spread even if this bullying strategy undermined cooperative food gathering altogether, depressing the absolute fitness of every individual in the population, even that of the thief. For selection is sensitive to relative, not absolute, fitness. Hence cooperative behavioral patterns are hard to build and maintain.
Kim Sterelny, Thought in a Hostile World, p. 124-125.