Inside Ancient Toolkits: Partnership Seeks Primates’ Wooden Tech

December 12, 2024

Authored by:

John DiConsiglio

Hike deep within the Taï Forest of Côte d ́Ivoire and you may see wild chimpanzees using large tree branches like hammers to crack open nuts.

Then travel to the Phang Nga National Park in Thailand to catch long-tailed macaques wielding the same type of makeshift wooden tools.

That's the itinerary George Washington University Professor of Anthropology David R. Braun is taking as part of a National Science Foundation (NSF)-supported collaboration with experts in the Columbian College of Arts and Science (CCAS) Physics Department and fellow anthropologists at the Max Planck Institute for Evolutionary Anthropology.

Braun and his partners aren't just interested in primate meal prep. Using a combination of investigative fieldwork and complex machine learning calculations, they're matching the chimps' modern toolkits to fossilized wood samples from millions of years ago-and they may be transforming our understanding of human technology along the way.

"Wooden tools, so far, are almost entirely absent in the early record of human material culture," Braun said. The oldest currently-known wooden tools date back about 500,000 years-as opposed to better-preserved stone tool evidence from approximately 2.5 million years ago.

But, since both modern human societies and nonhuman primate species use plant materials far more often than stone, Braun said there's good reason to suspect that simple pounding wooden tools predate sharp-edged ones.

"It makes sense that [primates] used wooden tools-we just have no evidence of it," said Braun, the director of the Koobi Fora Field Schoolwhich, in partnership with the National Museums of Kenya, offers students on-the-ground paleoanthropology experience at its Kenya field site.

Chimpanzee wooden tool: A branch from a tree in the Täi Forest showing evidence of the damage caused by cracking nuts. The team is looking for this same damage on fossilized wood from Kenya.

But, as Braun explained, anthropologists face a two-fold challenge in adjusting the archaeological record to include wooden tools: First, they must uncover wooden fossils that have survived damage from factors like natural decay, acid rain and fungus and insect boring. Then, they need to devise a fool proof method for identifying them-"a methodological shortfall," he said, that has so far eluded them.

That's exactly what Braun and his colleagues-including CCAS Professor of Physics Chen Zeng-are setting out to change. Braun and his team are observing and documenting modern primate wooden tool-use from West Africa to Southeast Asia. At the same time, they are collecting fossilized wood from the Koobi Fora field site in Kenya's Lake Turkana basin, with the help of the program's CCAS students.

As an undergraduate student at the Koobi Fora site, Victoria Rainis, B.S. '23, M.S. '24, collected fossilized wood with signs of behavioral use. Rainis, a former Luther Rice Fellowat GW and currently a Ph.D. student in Braun's lab, explained, "The goal was to not only find these fossilized wood tools but also to understand how old they could be, which is why we tried to find fossilized wood tools that were in situ-within a sediment layer-which would allow them to be dated."

From field to lab

The team then ships 3D models of both modern and fossil wooden samples back to Foggy Bottom where Zeng's team, which will include CCAS graduate students under the NSF grant, is developing computer vision and machine learning models that can reliably diagnose tool-like percussive damage-both on the surface of wooden tools and within their internal cellular structure.

"We're trying to extract unique patterns from two kinds of woods," Zeng noted. "In one, someone actually saw chimpanzees using them [as tools]. The others are 2 million-years-old. Nobody is around who saw it!"

While the research is in its early stages, the team believes it may confirm that our lineage of technological capacity stretches at least a million years longer than previously thought.

Fossilized wood from the Koobi Fora Formation. Specimens were collected from sediments that are over 4 million-years-old.

"The multidisciplinary approach-combining direct observations of tool use in living primates with archaeological artifacts found in deep time together with AI pattern recognition-will allow us to gain new insight into our early cultural evolution," said Max Planck Institute group leader Lydia Luncz, one of the primary partners with the anthropology team.

At the outset of their research, Braun and his team traveled to Côte d ́Ivoire in 2022 where they identified 57 wooden tools at 30 different sites, including wooden hammers and anvils with damage patterns consistent with tool use.

The new three-year $300,000 NSF grant will help expand both the field and lab portions of the project, including the team's January trip to Thailand to observe primate tool use firsthand. The project is also using controlled experiments-including a robot arm that simulates primate hammering action-to pinpoint how variables like moisture content in the wild or the percussive force of different species alter wooden samples.

Long term, Braun said the project holds potential implications for everything from rethinking technology evolution to perhaps a new understanding of human brain development. For now, Braun is confident that the team is filling a blank page in the archaeological textbooks.

"This is a big part of the geological record that we just don't have," he said. "We're opening up possibilities that extend as far back as we can find them."