Archaeologists Found a 476,000-Year-Old Wooden Structure. No One Knows Who Built It.

4 min readHere’s what you’ll learn when you read this story:Stone Age hominins were long thought to work almost exclusively in stone, since little else survived in the archaeological record.At Kalambo Falls in Zambia, archaeologists have excavated two interlocking logs deliberately shaped with tools by early humans.At least 476,000 years old, the logs are the earliest known wooden structure. The names of the three periods of the Stone Age end with the suffix -lithic for a reason. Since stone endures while other building materials erode away, it’s long been assumed that our most ancient ancestors worked exclusively with stone tools and created only stone structures.But Homo sapiens weren’t the first hominins to build with something other than stone. At Kalambo Falls, a site perched on the Kalambo River in the tropical woodlands of northern Zambia, a team led by University of Liverpool archaeologist Larry Barham pulled something extraordinary from the river sediments. It appeared to be the remains of a wooden structure, cut and shaped with stone tools, and buried beside it were several more tools made of wood. It’s one of the few wooden artifacts to survive from half a million years ago—and it’s also the earliest known wooden structure built by human hands.Ever since excavations led by John Desmond Clark in the 1950s and 1960s, the Kalambo River basin has been known for its unusual ability to preserve troves of prehistoric artifacts related to humans. The remnants of the newly discovered wooden structure hadn’t been exposed to the degrading effects of oxygen because it was buried in river sediments for millennia, and the silica minerals in the water helped give it the strength to last. However, the logs were too ancient for radiocarbon dating. Instead, researchers turned to luminescence dating, which gauges radioactivity in the minerals of the surrounding sediment to establish when those grains were last exposed to sunlight. The results showed that the wood was at least 476,000 years old, pushing the age of the discovery well past the oldest known Homo sapiens fossils, a 300,000-year-old find from Morocco.“[We found] two interlocking logs joined transversely by an intentionally cut notch,” Barham and his colleagues wrote in a 2023 study published in Nature. “This construction has no known parallels in the African or Eurasian Palaeolithic.” Older worked wood does exist, with the earliest known example being a fragment of polished plank from the Acheulean site of Gesher Benot Ya’aqov in Israel that’s more than 780,000 years old. But a plank is a single object. At Kalambo Falls, someone shaped two logs to fit together, which is the first evidence anywhere of wood used to build something.For decades, wood seemed to play only a bit part in hominin toolkits: a shaft for a spear, a handle for an ax, or kindling for a fire. Ancestors like Homo erectus were cast as nomads who were unlikely to build anything intended to last. So who notched the Kalambo logs? No one knows. H. erectus, who lived from 2 million to 100,000 years ago, is the obvious suspect. Homo heidelbergensis is another, since a skull from that species has been found elsewhere in Zambia. And at Florisbad in South Africa, modified wooden objects turned up in spring deposits alongside the remains of a later species, Homo helmei.What type of structure these logs were intended to have been part of is unclear. Based on slightly modified wedges of bark and wood that appeared later in the archaeological record, Barham and his team think it may have been a wedge or a portable work base, but the researchers still stress that “this unusual object has no parallel in the Middle Pleistocene record.” The team created digital 3D models to further study what the notches and other marks in the parts could possibly tell about their usage. They rotated and refitted the 3D models in order to examine the find without risking damage to the actual artifacts, and also experimented with wood specimens to see if water would erase tool marks or create marks that looked intentional. It turned out that water could smooth the edges of wood, but it was unable to carve out marks like those in the artifacts.The notched wood pieces might have worked something like the Lincoln Logs that Barham used to build with as a child. Both have notches in them that allow the pieces to sit on top of each other without easily coming loose. They will remain stable and refuse to slip under pressure. While it’s unlikely that Homo erectus and other human ancestors living half a million years ago were constructing entire houses, the notches are possible evidence of needing a framework to stay in place, whatever that framework was for. It might have been intended for a platform or walkway, or as storage or shelter. In 2026, Kalambo Falls was tentatively added to Zambia’s UNESCO World Heritage list for its exceptional record of preservation of such ancient artifacts.“The interlocking logs [show] the combination of two or more parts to make a construction, enhancing our understanding of the technical cognition of these toolmakers,” said Barham. “Exceptional conditions of preservation give us this glimpse of a capacity to create a built environment by hominins hitherto perceived as mobile foragers with limited technological diversity.”Elizabeth Rayne is a creature who writes. Her work has appeared in Popular Mechanics, Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.