From New Scientist:
Seeing red bears fruit for primates
* 05 June 2007
* NewScientist.com news service
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 traits among members of the primate family tree.
Three-colour vision appeared in species that branched off the tree earliest, showing that it evolved before traits such as red hair and red skin.
These traits were most likely to evolve in species that live in groups and select mates by sight, unlike solitary species which rely on scent signals (The American Naturalist, DOI: 10.1086/518566).
Despite our penchant for rouge and red lipstick, that sexual selection pressure may be relaxed in humans.
About 10 per cent of men lack red receptors, much higher than any other primate tested.
Primates, sperm, and sexual promiscuity: here.