From Scientific American:
Chimpanzees may comfort others in distress in ways very similar to how people do, according to what may be the largest study of consolation in animals by far. The new findings in our closest living relatives could help shed light on the roots of empathy in humans. The spontaneous consolation of someone in distress with a hug, a pat on the back or other friendly display of physical contact has been studied in human children as a sign of sympathetic concern for others for decades. This kind of demonstrative empathy is often thought to be a large part of what sets humanity apart from other animals.
To better understand how empathy might have evolved in our lineage, animal behaviorist Teresa Romero of Emory University and her colleagues studied roughly 30 chimpanzees housed outdoors at the Yerkes National Primate Research Center. Over a span of eight years they documented cases where uninvolved bystanders offered comfort to recent victims of aggression. Whereas most studies on animal consolation typically involve looking into a few hundred cases of conflicts and their aftermaths, “ours is based on an analysis of about 3,000 cases,” Romero says.
Picture: CHEER UP: Chimpanzees spontaneously console others in distress with friendly body contact. Here, an adult male [right] who was screaming loudly after losing a fight with a rival was approached by a juvenile [left] who put an arm around him. Frans B. M. de Waal.