Chimpanzees recognize their pals by using some of the same brain regions that switch on when humans register a familiar face, according to a report published online on December 18th in Current Biology, a Cell Press publication.
The study - the first to examine brain activity in chimpanzees after they attempt to match fellow chimps' faces - offers new insight into the origin of face recognition in humans, the researchers said.
"We can learn about human origins by studying our closest relatives," said Lisa Parr, a researcher at the Yerkes National Primate Research Center, Emory University. "We can discover what aspects of human cognition are really unique and which are present in other animals."
Earlier studies had shown that chimpanzees, like humans, are adept at recognizing their peers. "We knew [from behavioral studies] that chimps and humans process faces similarly," Parr said. "We wondered whether similar brain regions were responsible, and, for the most part, they seem to be."
In the study, the researchers examined brain activity (as reflected by blood sugar metabolism) in five chimpanzees by using Positron Emission Tomography (PET) scans. (Parr noted that the Yerkes National Primate Research Center is the only center of its kind to have on-site MRI, PET, and cyclotron facilities, making studies like Parr's possible.) The chimps were shown three faces, two of which were identical, while the third was of a different chimp. Subjects were then asked to indicate the faces that matched. In other trials, the chimpanzees did the same matching task with clip art images.