Whether it’s a college student showing their roommate their favorite song, or a child showing their parents a dirt rock they found on the ground, !”), people love to share things they find fascinating for the sheer joy of it. It has been long believed that the human desire to force your loved ones to watch your favorite movie is a characteristic of humanity. This instinct is not shared by our primate relatives.
An animal behavior researcher might still wonder from time to time if an act considered unique to humans might be found in chimps or orangutans, bonobos, or gorillas.
A chance observation in Uganda’s Kibale National Park gives a hint that such a behavior might exist. Further research on chimps sharing for the fun of it might be worthwhile.
The ability to “share” attention is a key development in human evolution and a precursor to more complex cooperative behavior. Babies as young as 10 months hold out items for their caretakers to see, with seemingly no other purpose beyond letting mom, dad or big sister in on something they find cool or interesting. “It is crucial that we engage in joint action together from an early age.” Katie Slocombe, a senior author of the study and a comparative psychologist at York University in England, says, “Being motivated to do this a lot is essential.”
Chimps are not known to share their attention. They can direct the attention of human caretakers or companions to communicate their needs. A chimp might point out a spot on its body that it needs to be groomed, or gesture to a toy it likes to play with.
But Slocombe and her team were astonished in the midafternoon on May 18, 2019, when they were studying the Ngogo chimp community in Kibale and saw something remarkable. An adult female named Fiona was fiddling with a leaf while her infant was in her lap and her mother, Sutherland, was by her side. Fiona held the leaf out in front of Sutherland, making small adjustments to ensure it was in her eyes until she finally looked down at it. Fiona stopped fiddling with the leaf after her mother saw what she was doing. Slocombe, who has been working with chimps almost two decades, was stunned. Slocombe says, “I’ve never seen them perform anything like that.”
This was a once-in-a-lifetime event that has never been repeated, either with Fiona or any of the other chimps Slocombe studies. Slocombe’s research was enriched by this one incident. It is difficult to confirm that Fiona was only trying to get her mom to pay more attention to Fiona’s actions, especially when there is only one observation. The team was especially interested in Fiona’s actions as part of a mysterious behavior called “leaf grooming “.
Although the exact purpose of leaf grooming is not known, chimps tend to inspect leaves after they have been grooming another chimp or themselves. Slocombe believes that the chimps may be trying to find parasites on the leaves during grooming in order to get a better view or to relieve anxiety.
The team looked through video footage to find other instances of leaf grooming behavior similar to what Fiona was doing when she gave the leaf to her mom. Looking back at 84 previous observations of leaf grooming performed by 37 different chimps from Ngogo and the nearby community of Kanyawara, the researchers saw no evidence that the behavior tended to lead to play or more grooming, so Fiona likely wasn’t trying to initiate either activity by holding out a leaf. Food sharing is another possible explanation, as the chimps never ate any of the leaves they groomed. Researchers are confident that Fiona did not have any ulterior motives other than to give Sutherland a leaf. She simply wanted to share her knowledge with her mom. Slocombe and her colleagues published their research on November 14 in Proceedings of the National Academy of Sciences USA.
Some people are skeptical that Fiona intended to share her experience of leaf contemplation only with her family. Garriy Shteynberg from the University of Tennessee Knoxville says that it does seem like the daughter is showing her mother something. It is encouraging to see this,” he said. However, he cannot tell if this is instrumental sharing or sharing just for the sake of sharing. Shteynberg also noted that Fiona, Sutherland and don’t exchange a “knowing glance” when sharing attention. He believes the chimps might be displaying a primitive version of a more complex behavior in humans. He says, “It would surprise that our closest relatives wouldn’t have some inkling about this kind of sociality.”
Michael Tomasello from Duke University, a psychologist, agrees that more evidence is needed. He says, “I would be more convinced if it were either a large number of observations under reasonably controlled conditions or even an experiment.”
Slocombe welcomes skepticism. She says, “I believe that’s very healthy for science.” She hopes that other chimpanzee researchers will be inspired by her findings to examine similar behaviors in their own subjects and see if they can replicate the results. She believes it would be interesting to see if other primate, such as dogs, just want you to look at something cool. She says that most dogs bring things to you because they want you do something with it. “But maybe not always.”