Chimpanzees in one part of Guinea crack and eat nuts while others refused, even when offered tools, a study published Monday found, and the difference could shed light on their culture.
As humans, we are said to have a cumulative culture: skills and technologies are passed down and refined from generation to generation, creating behaviors that are more sophisticated than a single person could conceive.
Some experts believe that this is unique to humans, and that traits such as chimpanzee tool use evolve spontaneously in individuals instead.
Her theory argues that animals can innovate certain behaviors without copying a model.
Evidence for this comes in part from captive chimpanzees that have been observed evolving seemingly independently tool use like scooping with a stick and swam with a leaf.
But these behaviors differ from comparatively more complex techniques like nut-cracking, and captivity is very different from the wild.
Kathelijne Koops, a professor at the Institute for Anthropology at the University of Zurich, therefore helped to design a series of experiments wild chimpanzees in Guinea.
While a population of chimpanzees crack nuts in Bossou, Guinea, another group just six kilometers away in Nimba does not.
Koops wanted to see if the Nimba population would develop the behavior when introduced to the appropriate tools.
The researchers set up four different scenarios: In the first, the chimpanzees encountered each other Palmnüsse in shells and stones with which to break them open.
In the second there were palm nuts in shells, stones, but also edible palm nut fruits. In the third they found the stones, unpeeled palm nuts and some cracked nutshells.
And the last experiment offered them rocks and coula nuts, which are cracked more frequently and more easily by chimpanzee populations that use this technique.
Each experiment ran for several months, mostly in 2008, but in some cases as late as 2011.
But while the experiment sites at Nimba were visited and explored by dozens of chimpanzees, who were filmed with on-site cameras, they never once attempted to crack a nut.
“Having observed nut-cracking on many occasions by Bossou chimpanzees, it was so interesting to see how the Nimba chimpanzees interacted with the same materials without ever cracking a nut,” Koops told AFP.
The study, published Monday in the journal Nature Human Behavior, suggests that nut cracking may actually be a result of a cumulative culture similar to that of humans.
Researchers acknowledged the difficulty of studying chimpanzees in the wild, including the inability to control the number of visitors to their sites.
Between 16 and 53 chimpanzees visited each site during the experiments, and primate behavior specialist Professor Gisela Kaplan, who was not involved with the research, questioned whether the numbers were enough to draw general conclusions.
“As in human society, the number of innovators is relatively small in animals, and the expression of innovation is also dependent on many social and environmental circumstances and pressures,” said Kaplan, professor emeritus of animal behavior at the University of New England, Australia .
The study’s authors acknowledge that there are other possible explanations for the chimps’ reluctance, including the possibility that they were simply not motivated to eat the nuts.
but chimpanzees cracking nuts in neighboring areas, they consider it unlikely that the Nimba population was disinterested in a new food source.
Koops said the involvement of a “normal-sized wild community” of chimpanzees and the length of the experiments provide insight.
“Of course it would be interesting to test other communities,” she said.
However, the results so far suggest that there “may be a greater continuity between the cultural evolution of chimpanzees and humans than is usually thought.”
Kathelijne Koops, field experiments find no evidence that chimpanzee nut cracking can be independently innovative, nature of human behavior (2022). DOI: 10.1038/s41562-021-01272-9. www.nature.com/articles/s41562-021-01272-9
© 2022 AFP
Quote: Copy or Renew? Study sheds light on chimp culture (2022, January 29), retrieved January 29, 2022 from https://phys.org/news/2022-01-chimp-culture.html
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