Glossy red lipstick is a powerful sexual signal, but humans are not the only primates to see red. Many others use red signals in sexual selection. But a study of 203 primate species suggests that colour vision didn’t originate for picking mates.
Instead it may have evolved for its benefits in foraging – picking out ripe fruit – and was retained for mate selection, say André Fernandez and Molly Morris of Ohio University, Athens. Most primates have three colour receptors, so see a richer visual spectrum than other mammals, which have only two.
Fernandez and Morris looked at the distribution of colour-vision…
