Researchers at Ohio University have found that after primates evolved the ability to see red, they began to develop red and orange skin and hair.
Humans, apes and Old World monkeys, such as macaques and leaf monkeys, all have trichromatic vision, which allow them to distinguish between blue, green and red colors. Primatologists have disagreed about whether this type of color vision initially evolved to help early primates forage for ripe fruit and young, red leaves among green foliage or evolved to help them select mates.