A chimpanzee at the Bioparc Zoo in Valencia, Spain, on October 13, 2024 (AFP / Jose Jordan)
It’s not an old monkey… For millennia, chimpanzees have continuously developed their abilities to use tools thanks to interactions between different populations of these primates, according to a study published Thursday in the journal Science.
This discovery – on primates closest to humans – is of great interest to our species, because it supports the idea that since time immemorial, our own ancestors have used their social ties to improve their techniques, explains AFP the main author of the study, Cassandra Gunasekaram.
Scientists have long marveled at the ability of chimpanzees to pass on complex behaviors and processes from one generation to another – such as using tools.
However, while human civilization has leapt from the Stone Age to the Space Age, the “culture” of the common chimpanzee — defined as socially inculcated attitudes — appears to have remained stagnant.
Cassandra Gunasekaram, a doctoral student at the University of Zurich in Switzerland, began her research wanting to challenge this assumption.
With her fellow researchers, she combined genetic data tracing ancient migrations of these primates across Africa with observations on the methods of gathering and hunting insects among dozens of groups of chimpanzees, the four subspecies being represented.
– Termite brush –
These methods and attitudes were categorized into three levels: those requiring no tools, those requiring simple tools (such as chewed tree leaves serving as sponges to absorb water running off trees), and those requiring more. elaborated including a range of tools.
A striking example of such a range of tools comes from the Congo, where chimpanzees use sturdy sticks to dig a tunnel to reach a termite mound. They then chew a plant stem to transform it into a brush and thus collect the termites in the tunnel that they themselves made.
The study published Thursday in Science shows that the use of sophisticated tools is strongly correlated with genetic exchanges between different populations of chimpanzees over the last 5 to 15 millennia. Suggesting in turn that such behaviors became more widespread when the groups interacted.
Chimpanzees living in regions where three subspecies are present showed the highest propensity to use the most sophisticated tools, highlighting that connections across different groups promote the development of knowledge.
In contrast, less sophisticated behaviors, such as toolless foraging, appear less linked to migrations and likely evolved independently in different regions.
– Perishable tools –
For Cassandra Gunasekaram, this paradigm reflects the evolution of the human species, and how the exchange of ideas and incremental innovation took us from the first abacuses to modern smartphones.
Our tools “have become so complex that a single person could not reinvent them on their own,” underlines the researcher.
But unlike their human cousins, chimpanzees have had far fewer opportunities to exchange new ideas with other groups: migrations take place gradually, driven by females of reproductive age moving into new groups to avoid inbreeding.
Analysis of ancient gene flow helped the team of researchers overcome one of the biggest obstacles in the study of chimpanzee “culture”: the lack of historical observational data, since the scientific study of chimpanzee he species only began about a century ago.
Furthermore, “chimpanzee tools are made of sticks and plant stems, all of which are perishable,” explains Cassandra Gunasekaram, making it almost impossible to trace the evolution of these artifacts through time.
Will chimpanzees ever rival human ingenuity? Certainly not. But over time, they could well become more efficient hunter-gatherers.
Some populations of chimpanzees have notably made considerable progress in cracking nut shells with rudimentary hammers and stones as anvils, cites Cassandra Gunasekaram as an example.
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