BioConcepts

unit of selectionSelektionseinheit (ger.)

• A group of entities of similar complexity that is located on one of various niveaus within the hierarchy of biological organization (e.g. genes, cells, individuals, groups, species) and in which natural selection takes place.  
  category selection see also level of selection

  1902

  it has been the psychophysical, not the physical alone, nor the mental alone, which has been the unit of selection in the main trend of evolution

  Baldwin, J.M. (1902). Development and Evolution Including Psychophysical Evolution: 26; cf. 30f.

  1909

  [in man] the group becomes the unit of selection because it contains within it an effective social situation, and […] selection on the basis of the struggle of group with group is its method

  Baldwin, J.M. (1909). Darwin and the Humanities: 46.

  1911

  the social Hymenoptera, where the group rather than the individual appeared as the unit of selection

  Anonymus (1911). [Note on the Annual Meeting of the Entomological Society of London]. Nature 85, 416.

  1938

  the colony is the unit of selection, to the exclusion of individual selection within the colony

  Sturtevant, A.H. (1938). Essays on evolution, II. On the effect of selection on social insects. Quart. Rev. Biol. 13, 74-76: 75.

  1943

  the family as a biological unit of great importance became established. Selection in these cases was not working alone upon the individual organism. The population was the unit of selection, much as the population of cells composing the multicellular individual was selected as a coordinated unit.

  Emerson, A.E. (1943). Ecology, evolution and society. The American Naturalist 77, 97-118: 116.

  1964

  The unit on which selection is operating is the group and not the individual

  Maynard Smith, J. (1964). Group selection and kin selection. Nature 201, 1145-1147: 1145.

  1970

  While rigorous formalization of the principles of natural selection is recent, it has been obvious in a general way that other units besidethe individual could be the unit of selection, and a great deal of theory-making has gone on for natural selection at other levels. While there is a superabundance of such theory, both rigorous and heuristic, and while many natural-historical observations are interpreted as arising through the agency of natural selection of molecules, cells, populations, species, and communities, there is virtually a complete absence of direct experimental or natural-historical verification of these interpretations. In view of the strong antitheoretical stance of most of biology, it is remarkable that, in the absence of much evidence, the concept of natural selection of units other than the individual is so widely accepted.

  Lewontin, R. (1970). The units of selection. Ann. Rev. Ecol. Syst. 1, 1-18: 2.