|
Trichromacy or trichromaticism is the condition of possessing three independent channels for conveying color information, derived from the three different cone types.〔(Color Glossary )〕 Organisms with trichromacy are called trichromats. The normal explanation of trichromacy is that the organism's retina contains three types of color receptors (called cone cells in vertebrates) with different absorption spectra. In actuality the number of such receptor types may be greater than three, since different types may be active at different light intensities. In vertebrates with three types of cone cells, at low light intensities the rod cells may contribute to color vision. ==Humans and other animals that are trichromats== Humans and some other mammals have evolved trichromacy based partly on pigments inherited from early vertebrates. In fish and birds, for example, four pigments are used for vision. These extra cone receptor visual pigments detect energy of other wavelengths, including sometimes ultraviolet. Eventually two of these pigments were lost (in placental mammals) and another was gained, resulting in trichromacy among some primates. Humans and closely related primates are usually trichromats, as are some of the females of most species of New World monkeys, and both male and female howler monkeys.〔 Recent research suggests that trichromacy may also be quite general among marsupials.〔Arrese, CA; Oddy, AY; Runham, PB; Hart, NS; Shand, J; Hunt, DM (2005). "Cone topography and spectral sensitivity in two potentially trichromatic marsupials, the quokka (''Setonix brachyurus'') and quenda (''Isoodon obesulus'')." ''Proceedings of the Royal Society of London Series B.'' 272(1595), 791-796.〕 A study conducted regarding trichromacy in Australian marsupials suggests the medium wavelength sensitivity, MWS, cones of the honey possum ''(Tarsipes rostratus)'' and the fat-tailed dunnart ''(Sminthopsis crassicaudata)'' are features coming from the inherited reptilian retinal arrangement. The possibility of trichromacy in marsupials potentially has another evolutionary basis than that of primates. Further biological and behavioural tests may verify if trichromacy is a common characteristic of marsupials. Most other mammals are currently thought to be dichromats, with only two types of cone (though limited trichromacy is possible at low light levels where the rods and cones are both active). Most studies of carnivores, as of other mammals, reveal dichromacy, examples including the domestic dog, the ferret, and the Spotted Hyena.〔Calderone, JB; Jacobs, GH (2003). "Spectral properties and retinal distribution of ferret cones." ''Visual Neuroscience.'' 20(1), 11-17.〕〔Calderone, JB; Reese, BE; Jacobs, GH (2003). "Topography of photoreceptors and retinal ganglion cells in the spotted hyena (''Crocuta crocuta'')." ''Brain Behavior and Evolution.'' 62(4), 182-192.〕 Some species of insects (such as honeybees) are also trichromats, being sensitive to ultraviolet, blue and green instead of blue, green and red.〔Rowe, Michael H (2002). "(Trichromatic color vision in primates )." ''News in Physiological Sciences.'' 17(3), 93-98.〕 Research indicates that trichromacy allows animals to distinguish red fruit and young leaves from other vegetation that is not beneficial to their survival.〔Sharpe et al. (2006). Advantages and disadvantages of human dichromacy. ''Journal of Vision'', 6, 213-223. Retrieved from http://www.journalofvision.org/content/6/3/3.full.pdf+html〕 Another theory is that detecting skin flushing and thereby mood may have influenced the development of primate trichromate vision. The color red also has other effects on primate and human behavior as discussed in the color psychology article.〔Diana Widermann, Robert A. Barton, and Russel A. Hill. Evolutionary perspectives on sport and competition. In 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「trichromacy」の詳細全文を読む スポンサード リンク
|