"We expected to find similar trends across all primate radiations that is, that the faces of highly social species would have more complex patterning," said Santana, who conducted the research as a postdoctoral fellow with the UCLA Department of Ecology and Evolutionary Biology and UCLA's Institute for Society and Genetics and who is now an assistant professor at the University of Washington and curator of mammals at the Burke Museum of Natural History and Culture. "We were surprised by the results in our original study on neotropical (Central and South American) primates."
In the new study, they did find the predicted trends, but they also found differences across primate groups differences they said they found intriguing. Are primate groups using their faces differently?
"In the present study, great apes had significantly lower facial complexity compared to monkeys," Lynch Alfaro said. "This may be because apes are using their faces for highly complex facial expressions and these expressions would be obscured by more complex facial color patterns. There may be competing pressures for and against facial pattern complexity in large groups, and different lineages may solve this problem in different ways."
"Our research shows that being more or less social is a key explanation for the facial diversity that we see," Alfaro said. "Ecology is also important, such as camouflage and thermal regulation, but our research suggests that faces have evolved along with the diversity of social behaviors in primates, and that is the big cause of facial diversity."
Alfaro and his colleagues serve as "evolutionary detectives," asking what factors produced the patterns of species richness and diversity of traits.
"When evolutionary biologists see these striking patterns of richnes
|Contact: Stuart Wolpert|
University of California - Los Angeles