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In evolutionary biology, Group selection refers to the idea that alleles can become fixed or spread in a population because of the benefits they bestow on groups, regardless of the fitness of individuals within that group.
While theoretically possible, critiques, particularly by George C. Williams (1966), John Maynard Smith (1964) and C.M. Perrins (1964) cast serious doubt on group selection as a major mechanism in evolutionary history.
Genetic variation, the raw material of selection, is much higher between individuals than it is between groups, particularly as groups grow larger. This tendency means that alleles are likely to be held on a population-wide level, leaving nothing for group selection to select for. In addition, most phenotypes, particularly physical ones, are not highly heritable in the first place.
Additionally, generation time is much longer for groups than it is for individuals. Assuming conflicting selection pressures, individual selection will occur much faster, swamping any changes potentially favored by group selection.
Recently Elliot Sober and David S. Wilson have argued that the case against group selection has been overstated. They focus their argument on whether groups can have functional organization in the same way individuals do and, consequently, if groups can also be "vehicles" for selection. For example, they suggest that humans do many things to reduce reproductive differences within groups, such as passing laws against polygamy. Alternatively, groups who cooperate better may have out-reproduced those which do not. Resurrected in this way, Sober & Wilson's new group selection is usually called multilevel selection theory.
Despite a serious attempt on their part, most interested parties remain unconvinced (see, for example, Cronk, 1994; Dawkins, 1994; Dennett, 1994).
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