Group selection

Group selection is a proposed mechanism of evolution in which natural selection acts at the level of the group, instead of at the more conventional level of the individual.Group selection isn't widely accepted by evolutionists for several reasons. First, it's not an efficient way to select for traits, like altruistic behavior, that are supposed to be detrimental to the individual but good for the group. Groups divide to form other groups much less often than organisms reproduce to form other organisms, so group selection for altruism would be unlikely to override the tendency of each group to quickly lose its altruists through natural selection favoring cheaters. Further, little evidence exists that selection on groups has promoted the evolution of any trait. Finally, other, more plausible evolutionary forces, like direct selection on individuals for reciprocal support, could have made humans prosocial. These reasons explain why only a few biologists, like Wilson and E. O. Wilson (no relation), advocate group selection as the evolutionary source of cooperation. Group selection is a proposed mechanism of evolution in which natural selection acts at the level of the group, instead of at the more conventional level of the individual. Early authors such as V. C. Wynne-Edwards and Konrad Lorenz argued that the behavior of animals could affect their survival and reproduction as groups, speaking for instance of actions for the good of the species. In the 1930s, R.A. Fisher and J.B.S. Haldane proposed the concept of kin selection, arguing that animals should sacrifice for their relatives, and thereby implying that they should not sacrifice for non-relatives; Haldane even jokingly introduced a mathematical basis for familial altruism, suggesting that he would die for two siblings or eight cousins. From the mid 1960s, evolutionary biologists such as John Maynard Smith argued that natural selection acted primarily at the level of the individual. They argued on the basis of mathematical models that individuals would not altruistically sacrifice fitness for the sake of a group. They persuaded the majority of biologists that group selection did not occur, other than in special situations such as the haplodiploid social insects like honeybees (in the Hymenoptera), where kin selection was possible. In 1994 David Sloan Wilson and Elliott Sober argued for multi-level selection, including group selection, on the grounds that groups, like individuals, could compete. In 2010 three authors including E. O. Wilson, known for his work on social insects especially ants, again revisited the arguments for group selection. They argued that group selection can occur when competition between two or more groups, some containing altruistic individuals who act cooperatively together, is more important for survival than competition between individuals within each group. Howard Rachlin, William M. Baum, and Carsta Simon have proposed group selection of behavioral patterns during ontogeny parallel to group selection during phylogeny. Their proposals provoked a strong rebuttal from a large group of evolutionary biologists and behavior analysts. Charles Darwin developed the theory of evolution in his book, Origin of Species. Darwin also made the first suggestion of group selection in The Descent of Man that the evolution of groups could affect the survival of individuals. He wrote, 'If one man in a tribe... invented a new snare or weapon, the tribe would increase in number, spread, and supplant other tribes. In a tribe thus rendered more numerous there would always be a rather better chance of the birth of other superior and inventive members.' Once Darwinism had been accepted in the modern synthesis of the mid-twentieth century, animal behavior was glibly explained with unsubstantiated hypotheses about survival value, which was largely taken for granted. The naturalist Konrad Lorenz had argued loosely in books like On Aggression (1966) that animal behavior patterns were 'for the good of the species', without actually studying survival value in the field. Richard Dawkins noted that Lorenz was a ''good of the species' man' so accustomed to group selection thinking that he did not realize his views 'contravened orthodox Darwinian theory'. The ethologist Niko Tinbergen praised Lorenz for his interest in the survival value of behavior, and naturalists enjoyed Lorenz's writings for the same reason. In 1962, group selection was used as a popular explanation for adaptation by the zoologist V. C. Wynne-Edwards. In 1976, Richard Dawkins wrote a well-known book on the importance of evolution at the level of the gene or the individual, The Selfish Gene. From the mid 1960s, evolutionary biologists argued that natural selection acted primarily at the level of the individual. In 1964, John Maynard Smith, C. M. Perrins (1964), and George C. Williams in his 1966 book Adaptation and Natural Selection cast serious doubt on group selection as a major mechanism of evolution; Williams's 1971 book Group Selection assembled writings from many authors on the same theme. It was at that time generally agreed that the primary exception of social group selection was in the social insects, and the explanation was limited to the unique inheritance system (involving haplodiploidy) of the eusocial Hymenoptera such as honeybees, which encourages kin selection, since workers are closely related. Early group selection models assumed that genes acted independently, for example a gene that coded for cooperation or altruism. Genetically-based reproduction of individuals implies that, in group formation, the altruistic genes would need a way to act for the benefit of members in the group to enhance the fitness of many individuals with the same gene. But it is expected from this model that individuals of the same species would compete against each other for the same resources. This would put cooperating individuals at a disadvantage, making genes for cooperation likely to be eliminated. Group selection on the level of the species is flawed because it is difficult to see how selective pressures would be applied to competing/non-cooperating individuals. Experiments from the late 1970s suggested that selection involving groups was possible. Kin selection between related individuals is accepted as an explanation of altruistic behavior. In this model, genetically related individuals cooperate because survival advantages to one individual also benefit kin who share some fraction of the same genes, giving a mechanism for favoring genetic selection.