Monkey Skin Color Linked to Breeding Success

Skin color displayed amongst a specific species of monkey is a good indicator of how successfully they will breed, a new study shows.

According to the research, skin coloration in male and female rhesus macaques is an inherited quality - the first example of heritability for a sexually-selected trait to be described in any mammal.

A team of scientists from the University of Exeter collected more than 250 facial images of wild rhesus macaques, which are native to South, Central and Southeast Asia. They display red skin coloring around the face, as well as the genital and hind-quarter areas.

Using these images, coupled with 20 years of genetic data, the researchers assessed whether the variation in red coloring influenced fecundity, or the ability to produce lots of offspring. They also determined whether their reddish tinge was heritable in male and female rhesus macaques - two necessary conditions for the trait to be considered under sexual selection.

The study showed that males that were darkly colored, as well as of high social status within the community, produced more offspring. Skin redness amongst females was also positively linked to fecundity.

Monkeys with darker skin were also more likely to produce offspring displaying the same trait.

"Some primates exhibit very noticeable skin colorings, in this case red, that we believe are linked to sexual success. It is not dissimilar to plumage shown by birds - the more striking it is, the more they will be noticed by potential mates," Dr. Lauren Brent, who was involved in the study, said in a statement.

While previous studies have shown that rhesus macaque skin coloration is involved in mate selection, this is the first to indicate that skin color has a genetic basis and is linked to breeding success.

"What is fascinating is that we can see that the deeper red coloring that seems to be favored in this species seems to be passed down from generation to generation, which is exciting."

The study was published in the journal Proceedings of the Royal Society B.