On the evolution of distinctive natal coat coloration in primates

Objectives Neonates of several primate species are born with very different pelage coloration from their parents but then assume adult coat color within weeks or months of birth. We set out to test the three conventional functional hypotheses for this distinctive transient natal coat coloration in primates (infanticide, allomothering, and confusion of paternity) as well as solicitation of maternal care, and across all neonate primates, background matching, and Gloger's rule (dark coats being associated with humid environments). Materials and Methods To examine the functional significance of neonate pelage coloration, we employed five different measures of distinctive coat coloration, new updated information on primate life histories, and a complete primate phylogeny of 286 species to control for shared ancestry. Results Across primates, we found a strong association between distinctive natal coats and the prevalence of infanticide but no support for allomothering or confusing paternity. We also found that species in which young have distinct natal coats have relatively shorter interbirth intervals, as well as a tendency to be weaned earlier which is unrelated to allomothering. Darker primate natal coats (whether distinctive or not) are not found in shadier, warmer, or wetter habitats. Discussion While distinct natal coats in primates are generally found in infanticidal species, we argue on logical grounds that this is not an advertisement to incoming males but instead neonate coloration solicits greater maternal care. This enables infants to pass through this infanticide-induced mortality-prone infant phase more rapidly. Conspicuous neonate coats in comparison to adults appear to act as a super-normal stimulus for mothers to hasten post-natal development of their offspring