Chimps Can Spot Faces Like Humans Do

by Charles Q. Choi, Live Science Contributor | July 16, 2015 11:54am ET

Chimpanzees can quickly identify the faces of other chimps, as well as those of human adults and babies. These new findings could shed light on human and chimp evolution, scientists  say.

Faces are key to human social lives, conveying key data about how one feels. As such, humans are wired to pay special attention to faces. For example, when pictures of faces are mixed in with pictures of other items such as cars and houses, people can detect the faces effortlessly.

Prior research has also shown that humans see faces differently from how they see other objects; for instance, facial recognition is severely hampered when people are shown upside-down faces, or when an image of a face is modified so that the nose and mouth are located beneath the eyes. These past findings suggest that the human brain analyzes faces in a holistic manner — that is, it understands images of faces by looking at the whole.

Increasingly, scientists find that chimps, humanity's closest living relatives, also see faces differently than they do other items. To learn more about the chimp response to faces, scientists first trained three adult chimpanzees named Chloe, Pendesa and Ai to find pictures of a chimp face, a banana, a car and a house among groups of other images on a touch screen. 

The researchers found that the apes recognized the chimp face very efficiently. "Chimpanzees very quickly find a face in the pile of various objects," said study lead author Masaki Tomonaga, a primatologist and comparative cognitive scientist at Kyoto University's Primate Research Institute in Japan.

However, the chimps' ability to detect a chimp face was significantly hampered when the face was upside down. This suggests that chimps may analyze faces holistically, like humans do.

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