The findings suggest that red skin and/or red-orange fur may be beneficial for use in social communication even in primate species that don't have particularly good colour vision. 

It's long been assumed that primates' colourful skin and fur is linked to their enhanced colour vision,  and the results may have implications for understanding why these traits exist in different species. Primates are known to use their red colour traits for communication with other members of their species, for example in signalling information about fertility or rank in the social hierarchy. 

“The fact that we didn't find that species with better colour vision are more likely to be colourful contradicts some long-held assumptions about the origins of the striking variation in colour we see within primates, and means we might have to take a closer look about what colourful red skin or fur is being used for in individual species. It shows that despite the large amount of work that has gone into investigating primate colouration in recent years, we still don't fully understand the pressures that have shaped the evolution of colour in our own closest relatives.” Lead author Robert MacDonald 

Read the full University of Bristol news item

‘Primate coloration and colour vision: a comparative approach’ by Robert MacDonald et al. in Biological Journal of the Linnean Society.