If no two faces are alike, researchers now have an idea why. We evolved unique faces in order to tell each other apart, according to a new study published in Nature Communications. As the researchers told Virginia Hughes at National Geographic, "It's like evolving a name tag."
The team arrived at this conclusion after comparing variation in human faces with that of other parts of the body. While people do come in all shapes and sizes, the researchers found that most diversity among people's faces. Genes reflect this variability, too. As Hughes describes, after analyzing DNA from more than 800 participants, the researchers found that the ones that code for structures in the face are more varied than others.
Digging even deeper, the researchers peered into Neanderthal DNA and found that two genes associated with facial features appeared in that species, as well. As Hughes writes, that finding suggests "that facial diversity evolved before modern humans did."
The team thinks that our unique faces most likely evolved to help us recognize one another—an ability that proved advantageous for survival. That hypothesis, however, is not definitive. As the scientists told Hughes, it could be that sexual selection acted as the primary driver of facial features. Similarly, one outside expert told Hughes, isolated populations that met and bred might have produced a grab-bag of facial features, producing the interesting and varied traits we see today.