Wild Chimpanzees Found To Teach Each Other Toolmaking

 Chimpanzees  

Social networks are known to be incredibly important for humans, and as researchers have found, the ability of individuals to learn from one another may have originated long ago in a common ancestor of chimpanzees and human.

Researchers have observed wild chimpanzees that see a friend making and using a new kind of tool, and then making one for themselves.

"Our study adds new evidence supporting the hypothesis that some of the behavioral diversity seen in wild chimpanzees is the result of social transmission and can therefore be interpreted as cultural," the team has reported in journal PLOS ONE.

The research points to the ability of individuals to learn from one another originated long ago in a common ancestor of chimpanzees and humans, they suggest.

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"This study tells us that chimpanzee culture changes over time, little by little, by building on previous knowledge found within the community," said Thibaud Gruber, a co-author of the study, in a statement. "This is probably how our early ancestors' cultures also changed over time."

Scientists already knew that chimpanzees in different groups have certain behaviors unique to their group, such as using a particular kind of tool. They suspected that wild chimpanzees learn those behaviors from other chimpanzees within their group, as scientists have observed in captive chimps. But they could never be sure.

Visualization of the static interaction networks for the RU1 behavior for all 30 individuals
- Image Source Hobaiter et al./PLOS ONE

The new study documents the spread of two new behaviors among chimpanzees living in Uganda's Budongo Forest. It shows that chimps learned one of them —  the making and use of a new tool called a moss sponge — by observing other chimps who had already adopted the behaviour. Chimps dip the tool in water and then put it in their mouth to drink.

In the video below, an individual extracts a leaf-sponge from his mother’s mouth before using it at the waterhole.

"Our study adds new evidence supporting the hypothesis that some of the behavioral diversity seen in wild chimpanzees is the result of social transmission and can therefore be interpreted as cultural."

The other behavior, picking up and re-using a similar tool called a leaf sponge discarded by another chimp, didn't appear to be learned by observing other chimps.

"We were incredibly lucky to be in the right place at the right time to document the appearance and spread of two novel tool-use behaviors, something that is extraordinarily rare in the wild," said Catherine Hobaiter, a lecturer in psychology at the University of St Andrews in Scotland who filmed the chimpanzees.

The first chimpanzee in the group ever seen making a moss sponge was "Nick," the 29-year-old alpha male — the top-ranked male in the group. Over the next six days, the researchers saw another seven chimps making and using moss sponges. In six of the cases, the chimps had recently watched another chimp making and using a moss sponge.

An analysis showed the chimps were 15 times more likely to start making and using a moss sponge if they had previously seen another chimp do it. That was not the case for the other new behavior, re-using discarded leaf sponges.

The researchers acknowledged that while the chimpanzees appeared to learn to make moss sponges from other chimps, they weren't exactly sure how — whether it was by direct observation, or independently trying to come up with a similar design, for example. That means they don't necessarily learn in the same way as humans.

Thibaud also noted that there is a difference in what humans can transmit to one another compared to apes that allows human culture to be far more complex than that of apes.




SOURCE  PLOS Biology

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