How it began
At Kalambo Falls, above a 235 meter waterfall on the Kalambo River in what is now northern Zambia, early humans shaped two logs and joined them crosswise with an intentionally cut notch. Luminescence dating of the surrounding sand places the logs at about 476,000 years old, give or take 23,000 years, which is earlier than the first known Homo sapiens. The find was made in 2019 by a team led by Larry Barham of the University of Liverpool and published in the journal Nature in September 2023.
Before it existed
Wood rarely survives from so early a period, so little is known about how early humans used it. Before this find, evidence for such ancient woodworking was limited to simpler items such as spears and digging sticks, and no joined structure of comparable age was known from Africa or Eurasia. Excavations at Kalambo Falls in the 1950s and 1960s had recovered wooden objects, but wear made it impossible to be sure that they were made by hominins.
How it works
The structure consists of two interlocking logs of large-fruited bushwillow. The smaller, upper log is about 1.4 meters long with tapered ends and a U-shaped notch, and it lies across the larger log, which passes through the notch. Tool marks on both logs show scraping and chopping. The researchers suggest the logs were part of a raised platform, walkway or foundation for a dwelling on the periodically wet floodplain. Waterlogged fine sediment preserved the wood.
What changed first
The team reported that the find extends the age range of woodworking in Africa and shows a capacity to shape tree trunks into large combined structures. They argued that it challenges the view that Stone Age humans were always nomadic, since a permanent water source and surrounding forest could have let people settle and build. Four later wooden tools from the same site, a wedge, a digging stick, a cut log and a notched branch, date to between 390,000 and 324,000 years ago.
Where it stands today
The dating relied on newer luminescence methods developed by Geoff Duller and colleagues at Aberystwyth University, which measure when sand grains were last exposed to sunlight and can reach further back in time than older techniques. The authors wrote that the find forces a re-examination of the use of trees in the history of technology.
