Evolution in color

2001/03/15 Galarraga Aiestaran, Ana - Elhuyar Zientzia

• Eboluzioa
• Zoologia

All the catarrino primates of the Old World, including humans, and those of the Cebidae family, the great monkeys of the New World, have a tricromatic vision, although other monkeys of the New World also have a partly tricromatic vision. The rest of mammals have dichromatic vision, that is, they are not able to distinguish between red and green.

XX. In the XIX century and to date, the tricromatic vision was based on the possibility of detecting fruit between the green leaves of the forest. However, researchers have found that animals with dichromatic vision can detect the type of light that normally reflects the fruit. The new, tender leaves of tropical plants are the only food they cannot detect. In fact, the new leaves of the African plants are red, while in South and Central America there are fewer monkeys with tricromatic vision and in addition only a third of the new leaves of the plants is red.

The food preferences of the primates of Uganda's Kibale National Park, as well as the color, chemical content and tenderness of the foods they choose, have been analyzed. On the one hand, they discovered that the new leaves, of red colour, besides being more tender, have more proteins and are more digestible. On the other hand, few primates eat only leaves, but their solution is when the food is reduced. Therefore, it is beneficial to be able to choose between the most nutritious and the most digestible. According to the researchers, this was what prompted the development of tricromatic vision, but not the detection of fruits between green leaves.

This work with the primates of the Old World, all with tricromatic vision, is the first to give a new vision of the development of tricromatic vision. Therefore, more studies will be carried out, even with the primates of the New World. In this way, the direct comparison of those who have dichromatic and tricromatic vision allows to know why some have the ability to see red.