Scientists discover that this diversity is partly due to lighting differences in their habitats
Have you ever wondered why some people have lighter eyes than others? Differences in iris colouration have traditionally been explained as a result of sexual selection, but a recent study led by researchers from the Department of Biological Sciences at the National University of Singapore (NUS) Faculty of Science revealed that this is partly due to differences in lighting in the habitats of primate species.
For over 20 years, studies focused on explaining variation in primate eye colouration have exclusively focused on eyes as visual signals for inter and intra-specific communication. This idea, however, has received little support from experimental studies in species other than humans. Other suggestions, like eye pigmentation patterns being used in camouflage against predators, have also received limited support.
Even though eyes help us navigate the world thanks to light entering that organ, the idea that eye colour diversity may have evolved due to different qualities of light being present in different habitats was never seriously considered.