Saddleback tamarin feeding on a green cricket

Colourblind monkeys are better at catching camouflaged prey than monkeys with normal eyesight, scientists have found.

Dr Andrew Smith, from Anglia Ruskin University’s Department of Life Sciences, led the project, which also involved scientists from the University of Stirling, the University of Cambridge and the University of Sussex.

Dr Smith and his team observed three species of tamarin monkey – saddleback, moustached and red bellied – in the Amazon rainforest in Peru and in captivity at Belfast Zoo, and found that levels of colour vision affects the rate and type of insect capture. Tamarins with normal colour vision (trichromats) catch more prey than colour blind tamarins (dichromats). However, the colour blind tamarins were significantly better at catching camouflaged insects, such as crickets.

Dr Smith said: “Colour blindness has several possible advantages for the tamarins. There is evidence in humans that dichromats see better in dim light than trichromats, it is thought that dichromats may have improved spatial vision and, crucially, dichromats appear to be superior at visually breaking camouflage.

“Experiments have shown that colour blind humans and non-human primates are better able to detect targets based on texture or outline while for colour normal humans and primates the target is camouflaged by colour. This means that colour blind wild primates actually have an advantage in their natural habitat when it comes to detecting both camouflaged prey and predators.”

Monkeys and apes are thought to have evolved good colour vision to help them find ripe fruit in trees, which is often a red or orange target against a green background. Colour blindness is more common in humans than in other apes.