A hug isn't a solely human impulse – bonobos do it too, to comfort distressed peers or to make up after a fight. Now, a study at a Congolese sanctuary finds that young bonobos who could handle their own emotions were better at offering others a shoulder to lean on.
What's more, bonobos raised by their mothers were much better at these social and emotional skills than orphaned bonobos.
The research, published in the Proceedings of the National Academy of Sciences, highlights the importance of mother-child bonds in developing such social and emotional abilities.
Among human children, the ability to modulate negative emotions has been linked to their ability to reach out and comfort another person in distress. Even when humans are young, and their ability to empathize isn't yet fully developed, they have an urge to comfort others, with hugs, kisses and caresses.
And those children who are better at expressing this "sympathetic concern" are the ones who seem to be able to regulate their emotions – for example, to calm themselves down sooner when they're upset.
There's a reason that someone who can tamp down a bad reaction is better at expressing sympathy, the authors said.
"Infants without effective [emotion regulation] do not orient to others because they cannot overcome their own personal distress in the face of another's distress," the authors wrote.
Other primates seem to have the same urge to hug it out, or kiss and make up. So a pair of scientists from Emory University in Atlanta wondered whether the same would be true in apes like the bonobo, a primate that's as close to humans genetically as chimpanzees, but with a reputation as a more docile, agreeable species.
The researchers went to the Lola ya Bonobo Sanctuary in Kinshasa in the Democratic Republic of the Congo, where many of the young rescues are orphans whose mothers were killed for bushmeat. They observed 373 different "post-distress" periods – 318 from right after a fight and 55 plain old tantrums – and watched to see how the others around them reacted.
Young bonobos raised by their mothers were almost three times more likely to reach out and comfort a distressed bonobo than orphaned bonobos were, the authors wrote. The orphans were more likely to cut and run, possibly because it's a good strategy to avoid tense scenes, the authors wrote. Where there's tension, trouble can often follow.
Bonobos with moms were also able to curb their negative emotional reactions more quickly, the authors said.
"Mother-reared juveniles were significantly less likely than orphans to recommence screaming once their vocalizations had stopped for 30 seconds or longer," they wrote.
All in all, the young bystanders who witnessed a fellow bonobo in distress were more likely to reach out and offer comfort than adolescents or adults.
"Juveniles react to the emotions of others but may not yet possess the cognitive filters, compared with adults, who evaluate the situation and are more inhibited and discriminating."