A study in scarlet Japanese macaques

JULY 8, 2019

by Kyoto University

From peacocks to butterflies and betta fish, mother nature never disappoints when it colors the males of a species. Which makes sense, in species with traditional sex roles, males are more involved in competing for mates, leading females to be choosier in their selection. As a result, males evolve to display even flashier and attractive ornaments.

These color changes also happen in many primates. For example, both male and female Japanese macaques display changing red skin coloration. But in new research published in Behavioral Ecology and Sociobiology a team from Kyoto University's Primate Research Institute propose that female red skin color acts as a 'badge' of their social statusand not—as previously thought—of fertility.

First author Lucie Rigaill explains that though female primates also display colorful traits, little is actually known about their role in mating.

Previous studies in other primates such as rhesus macaquesand mandrills have shown a link between red skin color variation and ovulation or fertility. Female Japanese macaques have also been observed to acquire 'redder faces,' linked to variation in sex hormone levels, leading researchers to assume that darker/redder faces are a sign of mating availability in the species.

"Our research is about better understating human sexuality by studying the evolutionary and biological roots of primate sexual communication," explains Rigaill.

Continued