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,
Eye color therefore should protect their eyes from direct exposure to sunlight. Wilson's disease involves a mutation of the gene coding for the enzyme ATPase7B, which prevents copper within the liver from entering the Golgi apparatus in cells. Instead, the copper accumulates in the liver and in other tissues, including the iris of the eye. This results in the formation of Kayser–Fleischer rings, which are dark rings that encircle the periphery of the iris. Eye color outside of the iris may also be symptomatic of disease. Yellowing of the sclera (the "whites of the eyes") is associated with jaundice, and may be