Cooperative eye hypothesis Cooperative eye hypothesis The cooperative eye hypothesis is a proposed explanation for the appearance of the human eye. It suggests that the eye's distinctive visible characteristics evolved to make it easier for humans to follow another's gaze while communicating or while working together on tasks. Unlike other primates, human beings have eyes with a distinct colour contrast between the white sclera, the coloured iris, and the black pupil. This is due to a lack of pigment in the sclera. Other primates have pigmented sclerae that are brown or dark in colour. There is also a higher contrast between human skin,
Evolution of the eye fast locomotion or navigation by vision. The rate of eye evolution is difficult to estimate, because the fossil record, particularly of the lower Cambrian, is poor. How fast a circular patch of photoreceptor cells evolve into a fully functional vertebrate eye has been estimated based on rates of mutation, relative advantage to the organism, and natural selection. However, the time needed for each state was consistently overestimated and the generation time was set to one year, which is common in small animals. Even with these pessimistic values, the vertebrate eye would still evolve from a patch of photoreceptor cells in