Humans are known for their ability to create sophisticated cultures, but chimpanzees display some of the same ability as well.
A new study from the University of Zurich uses markers of genetic similarity, or what they call a “genetic time machine,” to analyze chimpanzee populations and tool-use culture over thousands of years.
They discovered that migrating females often introduced cultural advancements into a new population, which then improved on the advancement to produce complex tool use.
Culture is a concept often associated with the smartest Great Ape of them all (us humans), but this idea isn’t exclusive to the eight billion members of the species. Many other animals, including primates, exhibit various cultures within their distinctive populations. For chimpanzees—humanity’s closest cousin along with bonobos—this culture manifests in the myriad ways these apes manipulate tools.
Some of these tools are relatively simple, such as using leaves to sponge up water from a tree hole, while others rely on a whole set of tools to accomplish complicated tasks. Because of humanity’s ability to build on knowledge over time, our species has developed immensely diverse cultures, but studies of chimps in the wild shows that this incredible skill isn’t exclusive to humans.
A new study from scientists at the University of Zurich (UZH) analyzed markers of genetic similarity, as well as foraging habits, across 35 disparate chimpanzee study sites. Using what they call a “genetic time machine” linking chimpanzee populations over thousands of years, they found that complex tool use could be found in even distant populations. The results of the study were published in the journal Science.
“As an example of such a toolset, chimpanzees in the Congo region first use a strong stick to dig a deep tunnel through hard soil to reach an underground termite nest,” UZH’s Cassandra Gunasekaram, lead author of the study, said in a press statement. “Next, they make a ‘fishing’ probe by pulling a long plant stem through their teeth to form a brush-like tip, pressing it into a point and deftly threading it down the tunnel they’ve made. They then pull it out and nibble off any defending termites that have bitten into it.”
Gunasekaram and her team organized behaviors into three groups: no tools, simple tools, and complex tools such as the fishing probe. In chimpanzee communities, sexually maturing females leave their social groups to find another community, an evolutionary trait that helps avoid inbreeding. Apart from adding diverse genes to a new community, the study found that female chimpanzees also provided advancements in culture when they arrived in their new communities.
“We made the surprising discovery that it is the most complex chimpanzee technologies – the use of entire ‘toolsets’ – that are most strongly linked across now distant populations,” UZH evolutionary anthropologist Andrea Migliano, a co-author of the study, said in a press statement. “This is exactly what would be predicted if these more advanced technologies were rarely invented and even less likely to be reinvented, and therefore more likely to have been transmitted between groups.”
The researchers suggest that developing this cultural complexity likely took place in steps, first with transmission between populations via female migrations and then implementing incremental changes until repurposing technologies altogether. Because this kind of cumulative culture is a feature of hominids broadly, researching this phenomenon in the context of one of humanity’s closest living relatives could give insight into the lives of past human ancestors as well as our current cousins.
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