July 15, 2020

Chimpanzees have culture and are in danger | Science


It was autumn of 1960 when that young woman without studies observed the unthinkable: a chimpanzee, David GreybeardHe had folded a branch and removed its leaves for fishing Termites with her. When Jane Goodall's discovery was made public, newspaper headlines had no doubts: forced to rethink what it means to be human. Making tools was no longer the defining characteristic of sapiens in front of the rest of the animal kingdom. The chimpanzees, so intelligent and adaptable, they had developed this skill and transmitted it to each other. Knowing them better helped us to know ourselves.

Half a century later, in 2011, the chimpanzee Nick He took a handful of moss, dipped it in a natural well, and, like a sponge, drained the water in his mouth to drink. Only three years later, more than half of the members of the community of Nick, the alpha male, drank water in this way. There were also witnesses: the primatologist Catherine Hobaiter and her team, who had witnessed the birth of a new cultural tradition in Uganda, the last of these behaviors that have been known since Goodall's first discoveries. Drinking soaking moss and not using leaves as a spoon is one of the techniques, behaviors or rites we know of chimpanzees. The largest study ever undertaken to learn about the cultural world of chimpanzees, recently published, has registered in total 31 of these cultural manifestations that they learn and transmit to each other, without it being a behavior inscribed in their genes.

But all those cultural traditions are in danger. They could disappear, with all their wealth and their important keys for the knowledge of the great apes, but also of human evolution. That is the main conclusion of this ambitious study, which has led scientists to study 144 communities of wild chimpanzees in 15 African countries for nine years. Where human pressure is greatest, the likelihood of chimpanzees developing and maintaining their own cultural tradition collapses. according to published in the magazine Science.

"The greater and closer the pressure of human activity, deforestation, roads, etc., the more they lose this ability to reproduce cultural behaviors", summarizes one of the primatologists who signs the study, Liliana Pacheco. "It is possible that they become extinct without us being able to study them and know those behaviors acquired through learning and that can be so valuable from an anthropological point of view," says Pacheco, director of the work that the Jane Goodall Institute in Spain does in Guinea and Senegal, from where it responds. Chimpanzees are in danger of extinction and populations of great apes disappear at a rate between 2.5% and 6% annually precisely because of the impact of human activity.

The chimpanzee is a cultural animal, with traditions and behaviors learned and transmitted in its four subspecies, and which extend into all its habitats – increasingly threatened – from the Democratic Republic of the Congo in Central Africa to Senegal in the westernmost region .

In Fongoli, in the warm Senegalese savannah, is the only group of chimpanzees that uses spears to hunt small monkeys and other animals with which to feed. A behavior that has achieved certain independence for some of the female hunters and that, by the conditions in which these chimpanzees live, could offer clues of how human ancestors evolved in similar circumstances. In West Africa, four different communities maintain a ritual of piling stones, that throw against certain trees, in what seems a symbolic behavior similar to that observed in human ancestors.

Understand them to understand us

"Understanding our closest cousins ​​helps us understand ourselves on an anthropological level," says Pacheco. And he warns: "If we do not do something, this cultural diversity will be history". As explained by the scientist of the Jane Goodall Institute, in the same environment, with the same conditions as fruits, stones and sticks, a community has been able to develop a technique to feed itself and a neighboring group another different one, which the mothers teach the young. The chimpanzees of Dindéfélo, which are the ones Pachecho studies, they fish termites and ants with sticks and open fruits against bark and rocks.

But how is humanity affecting this cultural heritage? To address this question, the 77 scientists who signed the study applied a range of noninvasive techniques to gather information from communities of chimpanzees that had never been studied, such as camera traps or collection of tools and artifacts that allowed inferring the existence of these behaviors. In total, these 31 cultural behaviors appeared that include techniques to obtain food or water (like termite fishing), to communicate (such as the use of leaves to produce a symbolic sound) and to improve their conditions (such as cooling their bodies or making mattresses with sheets to rest on).

"Understanding our closest cousins ​​helps us understand ourselves on an anthropological level, if we do not do something, this cultural diversity will be history," warns Pacheco.

"The analysis revealed a strong and robust pattern: the chimpanzees had reduced the diversity of behavior in the places where the human impact was high", explains the Primatologist Ammie Kalan, researcher at the Max Planck Institute for Evolutionary Anthropology, who has led this work. "On average, the diversity of chimpanzee behavior was reduced by 88% when the human impact was greater compared to locations with less human impact", adds Kalan.

Areas with greater human presence generally have lower density and abundance of chimpanzees, which can reduce the frequency of visible behaviors as that human impact increases. Added to habitat degradation and depletion of resources can lead to a marked reduction in social learning opportunities, "because chimpanzees are very sensitive and territorial," explains Pacheco.

"Our results suggest that populations of chimpanzees are losing their characteristic sets of behavioral traits and that a series of yet undiscovered behaviors can be lost without being described," warns the study. Science in its conclusions. Therefore, they demand that protected areas be created that safeguard their "capacity for cultural evolution". In particular, they suggest the "need for a new concept, cultural heritage sites for chimpanzees", something like those that Unesco protects for humans. It is not an occurrence of the researchers who sign the macro study. Regardless of the fact that it is a scientific necessity, it is a claim that is included in the Convention on Biological Diversity of the United Nations Environment Program, which requires the protection of biological diversity in its entirety, including the diversity of the cultural traditions of the fauna.

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