New Chimpanzee Culture Discovered, Others Lost Due to Humans
Eastern chimpanzees living in Democratic Republic of Congo display new tool kit.
Posted March 29, 2019
It's always exciting to discover new behavior patterns among wild animals, and recently a study of Eastern chimpanzees (Pan troglodytes schweinfurthii) living in the Bili-Uéré region of the Democratic Republic of Congo (DRC) showed these great apes using a new tool kit to obtain food. These very important results are published in an essay available for free online by T. C. Hicks and his colleagues in Folia Primatologica titled "Bili-Uéré: A Chimpanzee Behavioural Realm in Northern Democratic Republic of Congo."
The research was conducted over a period of 12 years at 20 survey sites. The researchers write, "Over a 12-year period, we documented chimpanzee tools and artifacts at 20 survey areas and gathered data on dung, feeding remains and sleeping nests. We describe a new chimpanzee tool kit: long probes used to harvest epigaeic driver ants (Dorylus spp.), short probes used to extract ponerine ants and the arboreal nests of stingless bees, wands to dip for D. kohli and stout digging sticks used to access underground meliponine bee nests. Epigaeic Dorylus tools were significantly longer than the other tool types, and D. kohli tools were significantly thinner. Tools classified as terrestrial honey-digging sticks were a significant predictor for brushed and blunted tool ends, consistent with their presumed use. We describe two potential new tool types, an 'ant scoop' and a 'fruit hammer.' We document an extensive percussive technology used to process termite mounds of Cubitermes sp. and Thoracotermes macrothorax and hard-shelled fruits such as Strychnos, along with evidence of the pounding open of African giant snails and tortoises."
An excellent summary of this seminal research can be found in an essay by Mike Gaworecki called "Widespread tool-using chimp culture discovered in Democratic Republic of Congo." He notes that the researchers described "an entirely new chimpanzee tool kit featuring four different kinds of tools: a long ant probe, a short probe, a thin wand, and a digging stick." These different tools are used on five different foods "including a variety of driver and ponerine ant species as well as honey from the nests of ground-dwelling and arboreal bees. And they’re not the only evidence of unique behaviors discovered among this chimp population." It turns out that these chimpanzees also build ground nests, "gorilla style" although there are predators including leopards and hyenas in the area. In most other areas chimpanzees sleep in trees.
Dr. Hicks believes "the most interesting quirk of the Bili-Uéré chimps is what he calls their "expanded ‘pounding behavior.’” Mr. Gaworecki writes, "Many chimpanzee groups are known to pound fruits against branches or roots in order to open them up, but the Bili-Uéré population also pounds open two different kinds of termite mounds, Cubitermes and Thoracotermes, across the entire 50,000-square-kilometer region Hicks and team surveyed." Dr. Hicks also notes this population "seems to totally ignore the widespread and abundant Macrotermes termite mounds, which are preyed upon using stick tools in many other chimpanzee populations such as, famously, at Gombe." Gombe is where Jane Goodall first observed tool-use in chimpanzees in 1960. He also believes that social learning is responsible for the development of the Bili-Uéré chimpanzee culture. The mechanism worked as follows: “A chimpanzee in a particular community invented a certain behavior, it became the community norm and then it spread through the surrounding forests via territorial expansions or immigrating females, until hitting some natural barrier.”
Human activities are robbing chimpanzees of behavioral diversity and their "wisdom of the elders"
"Human influence thus goes well beyond simple loss of populations or species, leading to behavioral change even where populations persist."
A very important observation in the above study showed that in areas where humans hunt chimpanzees they don't make ground nests and vocalize less than chimpanzees in other areas, most likely to avoid human hunters. Dr. Hicks laments, "Our activities are robbing these apes not only of their forests but their ‘wisdom of the elders,’ their ingenious cultural solutions to survival in the forests and savannas developed over hundreds or thousands of ape generations.”
These new results were reported at about the same time as an important study that showed that other chimpanzee populations are losing their culture. These results are summarized in an essay by Dr. Hjalmar Kohl and his colleagues published in the prestigious journal Science called "Human impact erodes chimpanzee behavioral diversity." This essay is not available for free online. The abstract for this extremely important project reads, "Chimpanzees possess a large number of behavioral and cultural traits among nonhuman species. The 'disturbance hypothesis' predicts that human impact depletes resources and disrupts social learning processes necessary for behavioral and cultural transmission. We used a dataset of 144 chimpanzee communities, with information on 31 behaviors, to show that chimpanzees inhabiting areas with high human impact have a mean probability of occurrence reduced by 88 percent, across all behaviors, compared to low-impact areas. This behavioral diversity loss was evident irrespective of the grouping or categorization of behaviors. Therefore, human impact may not only be associated with the loss of populations and genetic diversity but also affects how animals behave. Our results support the view that 'culturally significant units' should be integrated into wildlife conservation."
Hjalmar Kohl and his colleagues' essay is summarized in a piece by Michael Marshall called "Unique chimpanzee cultures are disappearing thanks to humans." He begins, "Chimpanzee cultures are disappearing. In places where their habitats have been heavily altered by humans, groups are abandoning unique behaviors and reverting to a core set of activities. The loss of chimpanzee cultural diversity is analogous to the way many human languages are disappearing because so few people speak them. It could make life more difficult for chimps in the long run because many of the lost behaviors allow the chimps to obtain additional food." As noted above, "in areas with a greater human footprint, the chimps perform fewer cultural behaviors. Each behavior was 88 percent less likely to occur in these human-dominated landscapes."
Clearly, our presence can have severe negative impacts on populations of chimpanzees that result in losses of cultural diversity. How human influence impacts cultural diversity in other species awaits further detailed study, but there's no reason to believe that we don't harm them as well.
As the Beatles correctly said, humans are "here, there and everywhere," and we are having devastating effects on countless species in an era called the Anthropocene, usually referred to as "the age of humanity." In reality, the Anthropocene is more correctly called "the rage of inhumanity," and clearly there is a lot of work to be done to lessen our global impacts.
The loss of chimpanzee and other cultures is a depressing sign of just how much damage we do. If we don't stop it and other assaults on nonhumans and their homes right now, not only will numerous other animals suffer, but so too will future generations who will inherit the messes we leave them. Surely we can—and must—do better for those who follow in our footprints. Let's work hard as a unified global community to make these footprints full of compassion rather than heartless destruction.