Study Tracks Gestures Shared by Great Apes

ST. ANDREWS, SCOTLAND—Earth.com reports that researchers led by Kirsty Graham of the University of St. Andrews have determined that as many as 90 percent of 70 identified communicative gestures used by wild bonobos and chimpanzees are shared by the two species, a rate much higher than would be expected to occur by chance. Such gestures include stroking the mouth to request food and raising arms to request grooming, Graham explained. The researchers asked human experiment participants to watch video clips of ten signs commonly used by chimpanzees and bonobos, and asked them to choose a correct meaning for each sign from four options. Some gestures, such as stroking of the mouth to request food, were identified correctly by the study participants more than 80 percent of the time. They correctly identified other signals about 52 percent of the time, Graham said. An earlier study conducted by University of St. Andrews psychologists identified gestures used by great apes in human children between the ages of one and two, and found that almost 90 percent of the 52 gestures used by the human children were shared with chimpanzees. Graham and her colleagues suggest today’s great apes and modern humans may have inherited a basic sign language from their last common ancestor. To read about why humans can throw harder and more accurately than great apes, go to "No Changeups on the Savannah."