Most animal populations are composed of genetically diverse organisms, some weaker and some stronger, resulting in the adoption of rigid dominance hierarchies. But this is not a universal structure of animal societies. Diverse species, from invertebrates to humans, have complex social structures in which individuals make sacrifices for the good of the group, or for the good of others. According to mathematical models, the answer may involve genetically determined, group-level aversion to inequity that counteracts the tendency of strong individuals to demand tribute from the weak. Sergey Gavrilets of the University of Tennessee, Knoxville, modeled such a system in which the evolution of “helping” behavior was an emergent property of the model.11 In this model, a group of imagined organisms of the same species interact and are ranked from strongest to weakest. When an individual finds a resource, a competitor may demand that resource, and the finder must then decide whether to give in or resist. Gavrilets’s model assumes that there are significant risks associated with losing a contest for possession of the resource, suggesting that the weaker individual will often give in. But the distribution of resources throughout a large group affects every individual in that group, not just a bully and its victims. If the demanding individual has more resources, and is therefore likely to be stronger than the resisting individual, it can be beneficial for an observer to intercede on behalf of the resisting individual, provided that the risk of injury or other costs are not prohibitive. In other words, in Gavrilets’s model, the selfish impulse turns out to be an individual-level aversion to inequality—a desire that no one else be stronger than oneself. Such behavior represents an IGE through which the ultimate share of resources in a population depends on the simultaneous expression of genes in many interacting individuals. Gavrilets’s model indicates that helping behavior can evolve in just 1,000 generations, a very short time span in the history of human culture, and can ensure a more equitable, although not perfectly even, distribution of resources even in the presence of oppressive individuals. Moreover, because the tendency of an individual to participate in a conflict is genetically determined, these “escalation thresholds” can evolve over time. Such helping is one of many examples of behavior that could be described as moral decisions, a topic that has attracted the attention of scholars for millennia. Some of the most convincing work on the evolution of morality suggests that it is not only the intelligence of humans that promotes moral behavior, but the demands of social groups in which humans find themselves embedded—the expectation to behave a certain way and to follow certain rules. (Genung et al. Beyond the blueprint. The Scientist: September 1, 2014)
Posted on: Fri, 17 Oct 2014 08:23:06 +0000
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