Primate coloration and colour vision: a comparative approach

Primates are remarkably colourful in comparison to other mammals. In particular, several species exhibit red-orange pelage or bright red skin, with the latter thought to signal status in intraspecific dominance interactions or to signal fertility. One potential driver of the interspecific diversity in red coloration is the primate visual system, which, uniquely among eutherian mammals, varies interspecifically and even between conspecifics in the ability to distinguish red and green (trichromatic colour vision). Previous comparative studies, however, have produced conflicting results regarding the proposed link between coloration and visual system. We employed an updated, sex-specific dataset of primate coloration and visual systems to re-examine the relationship between colour vision and red coloration across the entire order. With a few exceptions, increased colour visual ability is not significantly associated with the presence of red skin on the face or anogenital region, nor of red-orange pelage. We discuss possible reasons for the lack of colour-vision associations and suggest that dichromatic colour vision still facilitates effective signalling between conspecifics.