Humans can show empathy to family, friends, strangers and even to other species but whether other animals can show similar empathy is still unknown. Anecdotes of animals, apparently selflessly, helping other species seems to suggest that non-humans might share some of our ability to be flexible in the empathy we feel for others. Matthew Campbell and Frans de Waal, both from Emory University, USA, set about figuring out if chimpanzees, our nearest evolutionary ancestor, share our empathetic ability in the hope of revealing something about how competition could be switched for cooperation within chimpanzee and human societies.
To work out if chimpanzees could be empathetic to other species the team devised an experiment involving yawning. The type of empathy the team were testing for was not the advanced ‘theory-of-mind’ seen in adult humans but a type of involuntary mimicry of actions, for example contagious yawning. Links between yawning and involuntary empathetic mimicry are well established in humans and in chimpanzees. The team used the contagious yawn response to measure how empathetic the chimpanzees were when they were exposed to stimuli; more yawns were associated with a greater degree of empathy.
The team, who work at Yerkes National Primate Research Center, set about testing chimpanzees with videos of yawns to see if they would copy. The team produced a video of familiar faces yawning and one of unfamiliar faces yawning. As controls for these videos the team produced similar snippets of the same humans with neutral facial expressions. These videos would allow the team to determine if chimpanzees were empathetic to humans and if so if there was a difference in their response to humans they knew and those they didn’t.
The researchers also wanted to find out if chimpanzees showed an empathetic response to species they may never have encountered previously. To test this team used videos of gelada baboons yawning from a previous study, along with a non-yawning control video of the same baboons. Each of the yawning videos along with their non-yawning counterparts were shown to chimpanzees on an iPod touch and the number of times the chimpanzee yawned were recorded and compared.
When watching videos of humans the chimpanzees yawned more when the humans yawned than when they did not. Whether the humans were familiar or not did not make a significant difference to the chimpanzees’ response. This suggested to the researchers that the chimpanzees were showing empathy to both humans they knew and strangers. The number of times the chimpanzees yawned while watching the yawning and non-yawning geladas did not differ significantly, indicating that though the chimpanzees were showing empathy with the humans they did not with the geladas.
The team suggest that this could mean that chimpanzees do not need to know each yawning individual to show the empathetic contagion but the individuals do need to belong to a species the chimpanzees have a history of positive social interactions with. The team suggest that because the chimps were familiar with and had positive relationships with some humans they were able to respond empathetically with all humans whereas the chimpanzees might have simply not had the same interest in the gelada due to their unfamiliarity as a species. The team suggest that ‘gelada baboons were seen as a socially meaningless stimulis’.
‘Chimpanzees showed that the ability to connect with unfamiliar individuals is not unique to humans,’ the team concluded. Our closest living relatives are able to be empathetic to other species when they have a history of positive familiarity with them. The team suggested that this could affect the way we think about the origins of human empathy: ‘conditions within the human evolutionary lineage may have altered the expression of this ability, but flexible social engagement was probably already present in the last common ancestor with chimpanzees’.