Nov. 19 (UPI) -- While primates can look surprisingly different from each other, researchers have found that face coloration can reveal the evolutionary past of these species.
Scientists at UCLA have found that species living in smaller groups have simpler faces. This led them to believe that more color patches on the face results in greater facial variation across individuals within the species and could aid in identification, which would be more difficult in larger groups.
"Humans are crazy for Facebook, but our research suggests that primates have been relying on the face to tell friends from competitors for the last 50 million years and that social pressures have guided the evolution of the enormous diversity of faces we see across the group today," said senior author Michael Alfaro, in a statement.
A previous study looked at only Central and South American species. Now, scientists have taken a closer look at 139 Old World African and Asian species, which have been diversifying over 25 million years.
These Old World species are more or less social. Mandrils, for instance, can be found living in groups of 800 and more. Male orangutans, on the other hand, remain solitary, and the females are accompanied only by their offspring.
The researchers believe that color patterns on the face help monkeys and apes tell one another apart as well as identify individuals of one species from closely related species.
"Our research suggests increasing group size puts more pressure on the evolution of coloration across different sub-regions of the face," said Alfaro. The study was published in the journal Nature Communications.