After studying various genetic sequences, UC Berkeley researchers found that human evolution favors unique facial features that make individuals more recognizable.
In a study published last week in the science journal Nature, the researchers found that because of social interaction, the ability to discern differences among individuals is beneficial. They also found that social environment necessitates the evolution of differing facial features.
“The basic takeaway is that, on average, these regions associated with faces tend to have more genetic diversity, suggesting that something unusual is going on,” said Michael Sheehan, a National Institutes of Health postdoctoral fellow at the campus Museum of Vertebrate Zoology.
Sheehan co-authored the study with Michael Nachman, a campus professor of integrative biology who works as director of the museum.
According to Sheehan, diversity in facial features can be beneficial to individuals, especially in cases in which someone could be misidentified. The environment not only impacts interaction but also affects genetic makeup and physical facial features, according to the research.
Researchers compared the gene sequences that determine physical facial features to the overall human genome structure as well as the genes that determine height. The findings show that the genetic sequences that translate to facial features have more variation, on average, than other genetic sequences.
“If everyone looked the same, there would be no way to recognize others,” Sheehan said. “There are many situations when it would be costly to be confused.”
He said that one such example included mistaken-identity convictions in which someone is convicted of a crime because he or she was confused for another individual.
Previously published research in the field focused on the development of the human brain and how the brain recognizes faces but not the qualities of the human face from an evolutionary standpoint, according to Sheehan.
Robert Levenson, campus psychology professor, pointed out that there is good evidence showing that the brain contains a specialized area that aids in the complex process of facial recognition, which may imply that facial identity is centrally important in human evolution.
“(Nachman and Sheehan’s) research shows evidence that helps our understanding of processes that make facial evolution so important,” Levenson said.
Clark Barrett, an associate professor of anthropology at UCLA, said the research supports the idea that the increasing complexity of human networks results in improved recognition abilities.
“One of the things that is unique about our species is the degree to which we interact with non-kin as well as kin, and this would have selected for improved abilities to recognize and distinguish between individual people in our social networks, consistent with the findings of this work,” Barrett said in an email.
Sheehan hopes that the research will open up new areas of discourse and that psychologists and sociologists will study the types of situations in which facial individuality can be beneficial or detrimental.
“There are lots of types of interactions that people have,” Sheehan said. “What this research begs the questions of is under what circumstances individuality is the most beneficial or if there are any circumstances where this is bad.”