Tarsiers’ bulging eyes shed light on evolution of human vision
New Dartmouth study challenges prevailing view that trichromatic color vision, a hallmark of primate evolution, evolved only after they started getting up with the sun.
[…] The authors based their findings on a genetic study of tarsiers, the enigmatic elfin primate that branched off early on from monkeys, apes and humans. […] The authors analyzed the genes that encode photopigments in the eye to show that the last common ancestor of living tarsiers had highly acute, three-color vision much like living monkeys and apes. This finding would normally indicate a daytime lifestyle, but the tarsier fossil record showing enlarged eyes suggests they were active mainly at night.
These contradictory lines of evidence led the authors to suggest that early tarsiers were instead adapted to dim light levels, such as twilight or bright moonlight. These light conditions were dark enough to favor large eyes but still bright enough to support trichromatic color vision.
The authors said such keen-sightedness may have helped higher primates to carve out a fully daytime niche, which allowed them to better see prey, predators and fellow primates and to expand their territory in a world no longer limited to the shadows.