A chimpanzee family in the Democratic Republic of the Congo
Shutterstock/Sergey Ulyadnikov
Chimpanzees and bonobos exchange food with the person they shared food with in the first place, showing the same level of cooperation and reciprocity as a 4-year-old child.
While food-for-food exchanges are common in human societies, these exchanges are relatively rare among animals such as chimpanzees, bonobos, and gorillas. These apes groom and care for other apes of the same species, although exchanging food is less common.
The researchers tested 10 chimpanzees (pan troglodytes) and two bonobos (Panicus) share food with each other without prompting. In the laboratory, the apes were kept in separate pens and had reward choices on small plates in the space between the cages, allowing them to watch their partner choice. They were given the choice of pulling a plate with treats towards their cage or pulling a mechanism that delivered treats to both their own cage and another ape’s cage. They found that most apes chose to eat alone.
The team was interested in whether chimpanzees and bonobos were more likely to share food based on what partners initially chose. was repeated 10 times. Instead, they manipulated the first interaction by giving the apes only one choice, delivering food to either or both apes.
A similar choice test was given to 48 4-year-old children. They could choose treats just for themselves or for themselves and another child. Each participant in the trial received a reward tailored to their preferences, such as peanuts for chimpanzees, grapes for bonobos, and candy for preschoolers.
When apes saw other people intentionally sharing food with them, they returned the favor about 70% of the time. Nearly 80% of children made the same choice. When children felt ridiculed by others, they were unlikely to share food in return, but some apes would eat food about half the time, even if their partners were “selfish” at first. were shared.
The finding builds on a 2017 study that found that chimpanzees are more likely to return the favor to others if their partners risk trying to help, says Sarah Brosnan of Georgia State University. there is
The results suggest that our ancestors had to downgrade aggressive and dominant tendencies about food in order to foster cooperation and social connections.
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