Color Vision Deficiencies and the Evolution of Color Vision in Primates

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The ability to see color is something that many people take for granted. But, there are many people who go about life thinking that their vision is “normal,” when they are really experiencing their sense of sight through a color vision deficiency. A typical person relies on the color of fruit to determine its ripeness. Looking at a green banana signals to the brain that it is not ripe nor is it ready to be eaten; while looking at a brown banana signals that it is overripe and should be thrown away or used for baking purposes. What if you could not see the color and had to rely on the commonly overlooked details, like shape or texture to identify the fruit? Humans are not the only ones who can have color vision deficiencies…show more content…
Jacobs states that this “set the stage for alterations in photopigments and color vision.” He continues to explain that the M and L photopigments were derived from duplication of the original X-chromosome opsin gene. Because the three-pigment arrangement of trichromatic color vision is not typically shared with members of other anthropoid groups like the New World monkeys, the X-chromosome opsion gene duplication is thought to have occurred around 30-40 Ma at the base of catarrhine, or Old World monkey, radiation. New World Monkeys According to Jacobs, three or more types of cone pigments are typical among vertebrates. In eutherian mammals, primates are the sole species with three cone pigments. A more varied opsin gene/color vision arrangement is present in New World monkeys. Most of these monkeys have a total of six unique photopigment phenotypes. A male or female homozygous New World monkey can express one of three LWS opsin genes with the SWS gene, which is common in this species, then have any of the three possible combinations of two photopigments. Heterozygous females have different LWS genes on their X-chromosomes. Jacobs states that “the early developmental process of random X-chromosome inactivation results in a retina that contains three classes of cone pigments; since there are only three possible pairings, there are also
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