Two eyes positioned above a pair of nostrils that are themselves perched above a mouth—such is the layout of the face for vertebrate creatures ranging from sharks to humans. However well that arrangement may be optimized for finding and eating food, among mammals the face has taken on another critical role: communication. Nowhere is this function more apparent than in the human visage.
Primates in general have complex social lives, and they commonly use facial expressions in their interactions with one another. We humans have particularly expressive faces with which we convey such emotions as fear, happiness, sadness and anger. Researchers once chalked up the rich repertoire of human expressions to our having uniquely specialized facial muscles. But physical anthropologist Anne Burrows of Duquesne University has found that, in fact, the chimpanzee—the next most dramatic primate—differs little from humans in the musculature of its mug.