Human beings normally see in color. We are natural trichromats– we have three different color receptors that permit us to see a range of colors far broader than many other mammals. Even most other primates (with the exception of old-world monkeys) have only two kinds of color receptors. We are not the top of the color vision pile though. Jumping spiders are natural tetrachromats, with four kinds of receptors, and while there are no known mammalian tetrachromats, there are believed to be tetrachromats among birds, insects, reptiles, and amphibians.
That mammalian exclusion may be about to change. Since 1993 scientists in Oxford and Cambridge have been looking for a few women compared to whom, we may all be color-blind. These women would be the first known mammalian tetrachromats. In an odd twist of fate, the same genetic glitch that creates color-blind males may create females with better-than-usual color vision.
Newcastle University neuroscientist Dr. Gabriele Jordan, recently announced that she has identified a woman who is a “tetrachromat,” that is, a woman with the ability to see much greater color depth than the ordinary person. …
Jordan and her colleagues have for 20 years searched for people endowed with super color vision, or tetrachromatic vision. According to Discover Magazine, Jordan found a tetrachromat two year ago. Although the person is the first tetrachromat known to science, the researchers believe there are others.
Discover Magazine reports that Jordan and her team found many people with four types of cones but only one person passed the tests for tetrachromatic vision. The woman, identified as subject cDa29, is a doctor living in northern England. Jordan and her colleagues believe there may be other persons with tetrachromatic vision.