Evolution of Color Vision in Mammals - Essay Example

Along with visual system alterations, these changes have caused significant differences in the salience and nature of mammal color vision (Schwab et al 11). This paper will seek to discuss how color vision has evolved in mammals, especially with regards to marsupials, dolphins, and primates, discussing the relevant biological mechanisms, color vision utility, and variations in color vision among the listed mammals. Majority of mammals are not able to distinguish color at all, instead living in a sort of black and white environment.

Primates and marsupials are among the few mammals that can distinguish colors, which is proved by the distinct cells present in their retinas that are able to visualize colors (Schwab et al 23). Cone cells are fundamental in the ability to distinguish colors, thus color vision, while rod cells are found in animals that do not have the ability for color vision. Majority of mammals only possess the rod cells, except primates and marsupials. . There are only two types of rods; one that has a short wavelength sensation, which enables it to sense blue color, and another for long wavelength sensation that allows it to sense for red color (Schwab et al 24).

Color vision evolved from a vision in black and white with long wavelength sensing rods separated into red cones that sense red color and green cones that sense green color. Marsupials have also been found to have three forms of cones. As might be expected, color vision evolution in marsupials was distinct from the evolution of color vision in primates. This led to some distinct differences. The three cones that marsupials possess are not blue, red, and green. Rather, they are ultra violet, blue, and red because the rods for short wavelength sensing separated into ultra violet and blue cones (Gegenfurtner et al 44).

However, as of today, no one knows what color sensations these cones have. The only way to find out something about marsupial vision is through behavioral testing. The quendka and cathemeral dunnart marsupials have trichromatic vision that is different to that of primates since their S-cones can sense UV light, whereas the L-cones of the fat-tailed dunnart have a special sensitivity for the spectral region in the green-yellow region. It has been hypothesized that the L and M cones combine to allow for sensing of brown and cryptically colored green.

For the honey possum, the L-cones evolved to a further length than for fellow marsupials that conferred yellow-red sensitivity (Gegenfurtner et al 44). Color vision evolution for primates differs greatly compared to other eutharians. Primates are thought to