Group selection

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Group selection is an evolutionary theoretical concept that goes back to Charles Darwin and was worked out in 1962 by the British zoologist Vero Wynne-Edwards . The concept of group selection assumes that it is not individuals but groups of individuals that are those units on which the selection acts.

Early on, however, there were serious doubts that group selection was a crucial mechanism of evolution. More recently, some evolutionary biologists have advocated the rediscovery of group selection, albeit less as a fundamental mechanism and more as an emergent consequence of individual selection or as multilevel selection .

Problem after Charles Darwin

How can evolution based on individual selection also produce collective behavior? Darwin asked himself this question in Human Descent and Sexual Selection :

“It is extremely doubtful whether the descendants of the more sympathetic and benevolent parents or those who were most loyal to their comrades were raised in greater numbers than the children of selfish and betraying parents of the same tribe. Whoever was ready to sacrifice his life rather than betray his comrades, as many a savage has done, will often leave no heirs who can inherit his noble nature. "

- Charles Darwin : Human Descent and Sexual Selection

Darwin found his answer in what is now known as group selection:

“A tribe which comprises many members, who in a high degree possess the spirit of patriotism, loyalty, obedience, courage and sympathy and are therefore always ready to help one another and to sacrifice themselves for the common good, becomes over most other tribes prevail, and that would be natural selection. "

- Charles Darwin : Human Descent and Sexual Selection

The self-organization of the 'tribes' takes place through 'praise and blame', insightful understanding (the egoist also benefits from community success) - and religion, according to Darwin. Accordingly, there are also selection processes beyond the individual selection or the selection of relatives .

As it turned out later, these cooperation-stabilizing mechanisms, which Darwin already mentions, i.e. reputation and sanction ('praise and blame'), do not need the concept of group selection. It can also be stated that Darwin already had problems with the concept of group selection, as it contradicted the principle of individual selection he had discovered, especially with regard to the development of communal behavior:

"But one could now ask: where did it come from that within one and the same tribe a larger number of its members were first endowed with social and moral qualities and how was the standard of excellence raised?"

- Charles Darwin : Human Descent and Sexual Selection

The basic assumptions of the theory

In the biological-evolutionary sense, a group is defined as a set of individuals who mutually influence the degree of their evolutionary adaptation, be it for a fraction of a life span, be it for a lifetime or be it over several generations. Family relationships and spatial proximity do not necessarily play a role.

The original theory of group selection postulates that altruistic (selfless) individuals behave in this way mainly because it benefits their social group, which increases their chances of procreation and thus increases the genetic makeup of the altruistic individual compared to individuals in less altruistic groups promoted.

Vero Wynne-Edwards therefore assumes a selection that primarily results in the best for the group (hence: group selection), while the classical evolutionary theory sees the effect of selection primarily on the level of individuals and effects on the group level (negative and positive) only as a consequence of the individual selection.

Popular examples of group selection: If a group of animals of the same species, due to their genetic makeup, limits their reproductive rate to a level below their potential or refrains from using life-threatening body parts ('weapons'), this group - according to this theory - has an advantage over this a comparison group in which there are no such limits and which therefore has to accept mass deaths due to overpopulation and subsequent lack of food or death and injuries in rival fights.

Wolfgang Wickler notes in this connection: “ Behavioral researchers basically claim the same as Wynne-Edwards when they assume that comment fights were created in the service of the conservation of the species, because every damage fight that endangers or even destroys a conspecific goes against the principle of the conservation of the species. ”The ' inhibition to killing ' repeatedly postulated by Konrad Lorenz could easily be explained with the concept of group selection.

Contradictions

The contradiction to the basic principle already recognized by Darwin of the transmission of properties via the differential reproduction of individuals mediated by selection is evident: How can individuals reproduce successfully if their reproductive success in favor of others (unrelated) remains below the potentially realizable? Such behavior especially 'for the benefit of the group' (or the species) is evolutionary, i.e. not stable over generations. After all, individuals who prefer their own lineage can steadily increase their "relative individual reproductive success", that is, the "share of their genetic information in future populations" (= biological fitness ), compared to the altruists and eventually displace the latter. Postulates of a group selection (including “for the good of the species”) fail again and again because of this problem of “evolutionary stability”. (see also evolutionary stable strategy )

About 100 years after Darwin's comments on this concept, it became increasingly clear that it didn't work and Darwin was right to doubt it. Models for explaining group selection (e.g.) have seen numerous modifications, but none resolve the above contradiction. Either they make assumptions about population structures and gene flow that have no equivalent in nature, or they neglect the meaning of inherited characteristics, or they blur the levels of group and individual, or they confuse cause and consequence. Wilson & Sober even declare relative selection to be a special case of group selection, although the concept of group selection was formulated primarily to explain altruism between unrelated people . In any case, cooperation among related individuals is not altruistic in the narrower sense, as relatives, due to their common ancestors, pass on partially identical genetic information, as William D. Hamilton had already recognized. Koeslag sees group selection as the emergent result of individual selection. Although this is conclusive, it leaves the actual group selection problem, because group selection in the narrower sense means that individual selection is not necessary or even counterproductive with regard to cooperation. All those models that consider group selection as part of a multilevel selection are also breaking away from the original concept.

To date, not only is no group selection model available that would be able to explain the emergence of altruism groups in an environment with heterogeneous strategies, but also none that can explain how such groups - however formed - under realistic conditions should be evolutionarily stable compared to individual strategies, without using individual strategies on their part. The mere fact that various phenomena of cooperation are not conclusively explained is not an argument in favor of group selection. Many examples of alleged selflessness can also be explained after careful examination without group selection.

The idea that individual selection, in contrast to group selection, cannot bring about cooperation between unrelated people, is a popular misconception that has always been and continues to be the driving force behind the idea of ​​group selection. Selection at the level of individuals does not exclude that there are also characteristics that are advantageous for both the individual and the group (e.g. alarm calls against predators ). If group members are simultaneously threatened by external influences, then the interests of the group approach those of the individuals. In order for group selection to be noticeably effective, however, the rate of reproduction of entire groups would have to approximate that of individuals. There are very few examples of this in nature and even then the individual remains the unit of reproduction and group effects are essentially a consequence of individual selection, which some modern concepts of group selection also take into account (e.g.).

For the evolution of cooperation without group selection, reference is made to z. B.

See also

literature

  • Mark E. Borrello: Evolutionary Restraints. The Contentious History of Group Selection. The University of Chicago Press, Chicago / London 2010, ISBN 978-0-226-06703-2 .

Web links

Individual evidence

  1. ^ A b V. C. Wynne-Edwards: Animal Dispersion in Relation to Social Behavior . Oliver & Boyd, 1962.
  2. ^ GC Williams: Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought. Princetown 1972.
  3. ^ GC Williams: Evolution Through Group Selection . Blackwell, 1986.
  4. ^ J. Maynard Smith: Group selection and kin selection. In: Nature . Volume 201, 1964, pp. 1145-1147.
  5. ↑ a b c J. H. Koeslag: Evolution of cooperation: cooperation defeats defection in the cornfield model. In: Journal of Theoretical Biology. Volume 224, 2003, pp. 399-410.
  6. ^ F. McAndrew: New evolutionary perspectives on altruism - multilevel-selection and costly-signaling theories. In: Current Directions in Psychological Science. Volume 11, 2002, pp. 79-82.
  7. ↑ a b c D. S. Wilson, E. Sober: Reintroducing group selection to the human behavioral sciences. In: Behavioral and Brain Sciences. Volume 17, 1994, pp. 585-654.
  8. ↑ a b C. Darwin: The descent of man and sexual selection . I. Volume. Second edition. Translated from English by J. Victor Carus. E. Schweizerbart'sche Verlagshandlung (E. Koch), Stuttgart 1871, Chapter 5, p. 141, doi: 10.5962 / bhl.title.1419
  9. ↑ C. Darwin: The Descent of Man and Sexual Selection . I. Volume. Second edition. Translated from English by J. Victor Carus. E. Schweizerbart'sche Verlagshandlung (E. Koch), Stuttgart 1871, Chapter 5, p. 144, doi: 10.5962 / bhl.title.1419
  10. ^ A b E. Fehr, U. Fischbacher, S. Gächter: Strong reciprocity, human cooperation, and the enforcement of social norms. In: Human Nature. Volume 13, 2002, pp. 1-25.
  11. ^ A b E. Fehr, S. Gächter: Altruistic punishment in humans. In: Nature. Volume 415, 2002, pp. 137-140.
  12. ↑ M. Milinski, D. Semmann, H.-J. Krambeck: Reputation helps solve the tragedy of the commons. In: Nature. 2002, pp. 424-426.
  13. ↑ M. Milinski, D. Semmann, H.-J. Krambeck: Donors to charity gain in both indirect reciprocity and political reputation. In: Proceedings of the Royal Society London, Section B. Volume 269, 2002, pp. 881-883.
  14. ↑ W. Wickler, U. Seibt: The principle of self-interest. Causes and Consequences of Social Behavior . dtv 1981.
  15. ^ A b J. Maynard-Smith, GR Price: The logic of animal conflict. In: Nature , Volume 246, 1973, pp. 15-18.
  16. ↑ a b D. C. Dennett: E Pluribus Unum? Commentary on Wilson & Sober: Group Selection. In: Behavioral and Brain Sciences. Volume 17, 1994, pp. 617-618.
  17. ↑ BS Low: Why Sex Matters - A Darwinian Look at Human Behavior . Princeton University Press, 2000.
  18. ^ A b R. Trivers: The evolution of reciprocal altruism. In: Quarterly Review of Biology. Volume 46, 1971, pp. 189-226.
  19. ^ A b c R. Trivers: Social Evolution . Benjamin / Cummings, 1985.
  20. ^ DS Wilson, EO Wilson: Evolution for the good of the group. In: American Scientist. Volume 96, 2008, pp. 380-389.
  21. ^ DS Wilson, EO Wilson: Evolution - Group or Individual ? In: Spectrum of Science. 2009.
  22. ^ E. Sober, DS Wilson: Unto Others: The Evolution and Psychology of Unselfish Behavior . Harvard University Press, 1999.
  23. ^ A b E. O. Wilson: Kin Selection as the Key to Altruism: its Rise and Fall. In: Social Research. Volume 72, 2005, pp. 159-166.
  24. ^ DS Wilson: A theory of group selection. In: PNAS . Volume 72, 1975, pp. 143-146.
  25. ^ VC Wynne-Edwards: Evolution Through Group Selection . Blackwell Scientific, 1986.
  26. ^ WD Hamilton: The genetic evolution of social behavior . In: International Journal of Theoretical Biology , 7, 1964, pp. 1-16.
  27. ^ A b E. Fehr, U. Fischbacher: The nature of human altruism. In: Nature. Volume 425, 2003, pp. 785-791.
  28. ↑ T. Clutton-Brock, M. O'Riain, P. Brotherton, D. Gaynor, R. Kansky, A. Griffin, M. Manser: Selfish sentinels in cooperative mammals. In: Science . Volume 284, 1999, pp. 1640-1644.
  29. ↑ R. Axelrod: The evolution of cooperation . Oldenbourg, 2005.
  30. ^ PM Kappeler, CP van Schaick: Cooperation in Primates and Humans. Mechanisms and Evolution . Springer, 2005.