如何定义群体选择？.docxVIP

本概念的兴衰： Many early biologists accepted the idea of group selection without thinking very critically about it. For example, herds of grazing animals might be described as evolving to conserve their food supply over the long term. Herds that exercised restraint would be more likely to survive than those that quickly exhausted a critical resource. Other biologists, looking more closely at such arguments, found a flaw in the reasoning. Prudently managing a shared resource benefits all members of a group, including any "cheaters" who consume more than their share. Genes associated with cheating would therefore spread through the group, and the propensity for cooperative resource management would be undermined. The situation is all too familiar in human experience; it is the phenomenon that Garrett Hardin famously named "the tragedy of the commons." By the middle of the 1960s, ideas based on group selection were in deep disfavor, and the term itself was avoided in textbooks and the scholarly literature. When biologists observed behavior that appeared to benefit groups or species, they strove to explain it in terms of strictly individualistic selection. For example, animals might cooperate because they have genes in common ("kin selection") or because of the likelihood of reciprocal aid in the future. In this way, apparent altruism was interpreted as enlightened self-interest. It became almost mandatory for authors to assure their readers that group selection was not being invoked. Reassessment: Nevertheless, traits with public benefits and private costs do evolve by natural selection. Just because cheaters have a within-group advantage doesn't mean that they prevail in the total population. Within-group selection is opposed by between-group selection, and the final outcome depends on the relative strength of these effects. 俄罗斯套娃： "for the good of the group" behaviors are?locally?disadvantageous. If solid citizens are less fit than cheaters within their own group, then som