A new study has revealed that the remarkable diversity of human faces was the result of evolutionary pressure in order to make human faces more unique and recognizable as compared to other animals.
Michael J. Sheehan, a postdoctoral fellow in UC Berkeley's Museum of Vertebrate Zoology, said that people's highly visual social interactions are almost certainly the driver of this evolutionary trend.
Many animals use smell or vocalization to identify individuals, making distinctive facial features unimportant, especially for animals that roam after dark, he said but humans are different, he further added.
Michael Nachman, a population geneticist, said that the idea that social interaction might have facilitated or led to selection for us to be individually recognizable implies that human social structure has driven the evolution of how people look.
The researchers found that facial traits are much more variable than other bodily traits, such as the length of the hand, and that facial traits are independent of other facial traits, unlike most body measures. People with longer arms, for example, typically have longer legs.
They also compared the genomes of people from around the world and found more genetic variation in the genomic regions that control facial characteristics than in other areas of the genome, a sign that variation was evolutionarily advantageous.
Nachman further explained that all three predictions were met; facial traits are more variable and less correlated than other traits, and the genes that underlie them show higher levels of variation, while lots of regions of the genome contribute to facial features, so the genetic variation would be expected to be subtle, and it was but it was consistent and statistically significant.
The study is published in the online journal Nature Communications.
