Dichromacy

Dichromate (Greek di, " double " and chroma, " color" ) are organisms that have two kinds of cones ( color receptors ) in the retina.

While most vertebrates such as birds, fish, reptiles and amphibians are Tetrachromaten, most mammals are dichromats ( blue green). The reason for this may have been the nocturnal life of the ancestors, were lost in the two cone types. Only humans and Old World monkeys have a secondary again received a third pin by a gene duplication of the L- pin and thus are trichromats. As a third color they see red, useful for detecting red staining of skin and blood, which stress and other social signals are perceived.

Healthy people have three types of cones: red-, green-, and blue-sensitive. If one of these cone types of hereditary, individuals are called dichromats. Depending on which precipitates the three cone types, results in a protanopia deuteranopia or tritanopia.

Achromat | monochromate | dichromate | trichromatic | Tetrachromat | Pentachromat

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