Scientists have shown in recent decades that chimpanzees, like humans, transmit complex civilizations, including the use of tools, from one generation to the next. But as new developments have been adopted, human culture has advanced significantly from the Stone Age to the Space Age. The fact that chimpanzee civilizations have not evolved similarly implies that only humans possess the extraordinary capacity to develop increasingly complex cultures throughout time.
This has been challenged by researchers who study chimpanzees in the wild, who contend that some of the animals’ most sophisticated technologies—which involve using a variety of tools sequentially to uncover hidden food sources—were likely developed over time based on prior understanding.
Some of their most sophisticated behaviors might have been inherited and honed over many generations, according to a recent multidisciplinary study headed by the University of Zurich. The team’s work on this subject has been published in the journal Science.
Finding genetic connections
Lead author Cassandra Gunasekaram of the University of Zurich’s Department of Evolutionary Anthropology says, “As most chimpanzee tools, such as sticks and stems, are perishable, there are few records of their history to confirm this hypothesis—unlike human cases such as the evolution of the wheel or computer technology,”
A group of anthropologists, primatologists, physicists, and geneticists from universities and research centers in Zurich, St. Andrews, Barcelona, Cambridge, Konstanz, and Vienna collaborated on the new study to trace genetic ties between chimpanzee populations over thousands of years. They used new genetic discoveries to unearth important aspects of chimpanzee cultural history in ways that had never been possible before.
The initial phases of cumulative culture
From a total of 35 chimpanzee research sites around Africa, the authors gathered data on markers of genetic similarity—genetic evidence of ties between different groups of chimpanzees—as well as a variety of foraging behaviors that have been previously documented to be culturally taught. These behaviors were divided into three categories: those that didn’t require any tools, those that did, such using a leaf sponge to collect water from a tree hole, and the most sophisticated behaviors that needed a toolset.
Switching out instruments across generations
“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,” Gunasekaram says. “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.”
“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,” says corresponding author Andrea Migliano, professor of evolutionary anthropology at UZH. “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.”
How innovation is disseminated by female migration
In order to prevent inbreeding, sexually mature female chimpanzees—not males—move to new communities. In this manner, over the course of years, centuries, and millennia, genes move from nearby groups to those farther away. The authors of the study found that any new cultural advancements could be transferred to underdeveloped communities by these similar female migrations.
Additionally, the study demonstrated that when complicated toolsets and their reduced versions—that is, primarily the toolset components—occur at distinct study sites, the genetic markers suggest that female migrations formerly connected the locations. This implies that the simple versions were modified or added to throughout time to create the sophisticated ones. “These groundbreaking discoveries provide a new way to demonstrate that chimpanzees have a cumulative culture, albeit at an early stage of development,” Migliano continues.