Why we have different faces
The shape and configuration of a human face are much more variable, compared with other body parts, the study found. What's more, genes that have been linked to face structure vary more than DNA in other regions of the body. This suggests that the forces of evolution have selected for facial diversity, perhaps to make individuals more recognizable to other people, the researchers say, National Geographic said. "An individual may actually benefit from having a unique face," says lead investigator Michael Sheehan, a postdoctoral fellow at the University of California, Berkeley. "It's like evolving a name tag." There are many situations in which it might be evolutionarily costly to be confused with another person, Sheehan notes, such as if an enraged neighbor mistakes you for their enemy. "Or maybe you've done something fantastic and someone wants to give you a reward, but they give it to someone else instead," Sheehan notes. "Being cryptic could be harmful." That seems to be true for the paper wasp, Polistes fuscatus, a species that is "phenomenally diverse in their color patterning," Sheehan says. In 2011 his team reported that these highly social insects rely on their distinctive face and body patterns to recognize each other, which helps them keep track of who's who in the wasp hierarchy. (See "Wasps Can Recognize Faces.") In the new study, published today in Nature Communications, Sheehan and his colleagues analyzed a U.S. Army database that includes dozens of face and body measurements for thousands of its service members, from the distance between pupils to the length of the calf. Sheehan's team found that most body parts are internally consistent: If a person's hand is wide, it's usually long, too. Face parts, in contrast, are not predictable. "You mix and match," Sheehan jokes, "like Mister Potato Head." Detals also at