It’s a gesture that involves tapping two stones together without splitting them: this key behavior in human cognitive evolution has been observed in western gorillas, according to a published study. Nature.
“hit” And “percussion” With bare hands
Our ancestors went through many stages before making stone tools. there”Attack with bare hands“Considered as a prerequisite “Percussion with bare hands”. The latter makes it possible to create sharp pieces from a stone core. Early artifacts played a fundamental role in human evolution.
Researchers closely followed the daily lives of two gorillas, or 23 individuals, in the Republic of Congo. They were particularly interested in their eating habits, which they filmed. Of the nearly 300 minutes of footage, only five episodes “Attack with bare hands“Identified in two gorillas. In the middle of a meal, two young monkeys did not use stones, but pieces of termite mounds that they knocked together.
When feeding on termites, gorillas generally use two techniques. They can lick the surface of termite mounds directly or split them (this is the “technique”).Rumbling“). Why is this technique different? “Strike with Bare Hands” ? The “Rumbling“Holding a piece of termite mound in one hand while the other hand is empty, two young western gorillas demonstrate ingenuity by holding a termite mound in each hand.”Adults are very accommodatingShelley Masi, a researcher at the National Museum of Natural History, smiles. “Their purpose was certainly not to make sharp tools, but to find termites. She explains Science and the future. What matters is that they had a goal in mind and voluntarily took a new step to achieve it.”
The researchers did not anticipate the tools
This is not the first time such behavior has been observed in the wild. Japanese macaques (macaca fuscata), more distant from our lineage than gorillas, had already made this gesture. For scientists, modern fauna provides an opportunity to better understand the factors necessary for the origin of stone tool production. The next step in this fiction is, “Percussion with bare handsHowever, it implies additional qualities such as strength and precision.
This may be a major turning point in the evolution of the human race. Sometimes fragments are accidentally formed when monkeys use rocks. Bearded Subjas (Sabajus libidinous) keep making them but never use them. There are few examples of rock handling in untrained animals. Long-tailed macaques (Macaca fascicularis) is the exception. They find stones in the shape of an ax to open the shells.
Gorillas use some tools
Examples of tool use among gorillas are scarce. People in the West use fake tools like grass and sticks to scare away intruders. Some of them used a stick to measure the depth of a pond before crossing it. In the wild, this species is the least resourceful of the great apes. “The largest of animals, the gorilla does not need tools, he can use his strength,” explains Shelley Masi.
Emmanuelle Pouydebat, director of research at the CNRS, who participated in the study, explains Science and the future : “It is certain that this is not a cognitive problem because in captivity they solve problems involving tools very well. They can use sticks to get food hidden in mazes“Why this difference in behavior? It”Captivity effect“According to the researchers this may be questionable. That is, even if humans do not intervene directly, for example through learning, the absence of nature creates a different approach from animals.
Capuchin Capuchins produce and use sharp stones
brown capuchin (Sabajus appella) was the only organism that produced deliberately sharpened particles and used them arbitrarily without being taught. Individuals used these carved stones to receive rewardsInternational Journal of Primatology. The researchers found that the brown capuchins had the abilities because these monkeys had no teaching or training.Natural sensory, motor and cognitive skills to create and use cut stones“.
A study of western gorillas underscores the nutritional motivation of “behavior.”Attack with bare hands“Found in two young primates from the Republic of Congo. According to scientists, this foraging environment may have initiated this gesture in the last common ancestor between gorillas and humans.