Evolutionary Considerations

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The following hypotheses explore the role of evolution in dichromatism.

  • Adaptation: During the Second World War, the U.S. Army discovered that colorblind soldiers could distinguish camouflaged targets better than their counterparts with color vision could.[1] Further studies have shown that dichromats are better at detecting camouflaged targets in which the object’s color accounts for differences in texture between the object and its surroundings,[2] have sharper vision,[3] and may be less subject to the effects of “chromatic noise.”[4] Other studies suggest a dichromat advantage in mesopic vision and scotopic vision.[5] There is also a hypothesis that X-linked color deficiency leads to better discrimination against blue backgrounds, conferring and advantage to dichromats in fishing.[6] As a result, dichromats may have an advantage over trichromats in detecting some kinds of prey, which could explain higher rate of dichromatism in relation to other defects.[7]
  • Evolutionary Legacy: Another hypothesis posits that the high frequency of dichromatism in humans is due to a relaxation of pressure for trichromats in societies that have been traditionally pastoral and agricultural. Because color vision is less important to survival in these societies, positive selection for trichromatism would be relaxed.[8] Because the only genetic difference between a dichromat and a trichromat is in the opsin genes,[9] in agricultural-pastoral societies the ancestral dichromat phenotype not being a reproductive hindrance (and therefore not being subject to negative selection)—but rather the newer trichromat phenotype merely being more advantageous in pre-agricultural societies (subject to positive selection)—accounts for the relatively high frequency of dichromatism in these societies.[10]

Reference

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  1. ^ Reit, Seymour (1978). Masquerade : the amazing camouflage deceptions of World WAR II. New York: Hawthorn Books. ISBN 0-8015-4931-0.
  2. ^ Neitz, Jay; Neitz, Maureen (1 April 2011). "The genetics of normal and defective color vision". Vision Research. 51 (7): 633–651. doi:10.1016/j.visres.2010.12.002. PMC 3075382. PMID 21167193.
  3. ^ Jägle, Herbert; De Luca, Emanuela; Serey, Ludwig; Bach, Michael; Sharpe, Lindsay T. (23 August 2005). "Visual acuity and X-linked color blindness". Graefe's Archive for Clinical and Experimental Ophthalmology. 244 (4): 447–453. doi:10.1007/s00417-005-0086-4. PMID 16133025. S2CID 19873643.
  4. ^ Regan, B. C.; Julliot, C.; Simmen, B.; Viénot, F.; Charles–Dominique, P.; Mollon, J. D. (29 March 2001). "Fruits, foliage and the evolution of primate colour vision". Philosophical Transactions of the Royal Society B: Biological Sciences. 356 (1407): 229–283. doi:10.1098/rstb.2000.0773. PMC 1088428. PMID 11316480.
  5. ^ Hut, Roelof A.; Paolucci, Silvia; Dor, Roi; Kyriacou, Charalambos P.; Daan, Serge (3 July 2013). "Latitudinal clines: an evolutionary view on biological rhythms". Proceedings of the Royal Society B: Biological Sciences. 280 (1765): 20130433. doi:10.1098/rspb.2013.0433. PMC 3712436. PMID 23825204.
  6. ^ Grassavaro Gallo, P. (1997). "Do Congenital Color Vision Defects Represent a Selective Advantage?". In C. Dickinson; I. Murray (ed.). John Dalton's Color Vision Legacy. Manchester: Taylor & Francis. pp. 227–233. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: multiple names: editors list (link)
  7. ^ Regan, B. C.; Julliot, C.; Simmen, B.; Viénot, F.; Charles–Dominique, P.; Mollon, J. D. (29 March 2001). "Fruits, foliage and the evolution of primate colour vision". Philosophical Transactions of the Royal Society B: Biological Sciences. 356 (1407): 229–283. doi:10.1098/rstb.2000.0773. PMC 1088428. PMID 11316480.
  8. ^ Post, R. H. (1 September 1982). "Population differences in red and green color vision deficiency: A review, and a query on selection relaxation". Biodemography and Social Biology. 29 (3–4): 299–315. doi:10.1080/19485565.1982.9988503.
  9. ^ Neitz, Jay; Neitz, Maureen (1 April 2011). "The genetics of normal and defective color vision". Vision Research. 51 (7): 633–651. doi:10.1016/j.visres.2010.12.002. PMC 3075382. PMID 21167193.
  10. ^ Post, R. H. (1 September 1982). "Population differences in red and green color vision deficiency: A review, and a query on selection relaxation". Biodemography and Social Biology. 29 (3–4): 299–315. doi:10.1080/19485565.1982.9988503.