Tetrachromacy (from Greek tetra, meaning "four" and chroma, meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye. Organisms with tetrachromacy are called tetrachromats.
In tetrachromatic organisms, the sensory color space is four-dimensional, meaning that matching the sensory effect of arbitrarily chosen spectra of light within their visible spectrum requires mixtures of at least four primary colors.
Tetrachromacy is demonstrated among several species of birds,[2] fishes,[3] and reptiles.[3] The common ancestor of all vertebrates was a tetrachromat, but a common ancestor of mammals lost two of its four kinds of cone cell, evolving dichromacy, a loss ascribed to the conjectured nocturnal bottleneck. Some primates then later evolved a third cone.[4]
- ^ Figure data, uncorrected absorbance curve fits, from Hart, NS; Partridge, JC; Bennett, ATD; Cuthill, IC (2000). "Visual pigments, cone oil droplets and ocular media in four species of estrildid finch". Journal of Comparative Physiology A. 186 (7–8): 681–694. doi:10.1007/s003590000121. PMID 11016784. S2CID 19458550.
- ^ Goldsmith, Timothy H. (2006). "What Birds See". Scientific American (July 2006): 69–75.
- ^ a b Bowmaker, James K. (September 2008). "Evolution of vertebrate visual pigments". Vision Research. 48 (20): 2022–2041. doi:10.1016/j.visres.2008.03.025. PMID 18590925. S2CID 52808112.
- ^ Jacobs, G. H. (2009). "Evolution of colour vision in mammals". Phil. Trans. R. Soc. B. 364 (1531): 2957–2967. doi:10.1098/rstb.2009.0039. PMC 2781854. PMID 19720656.