Kalambo Falls structure

Two interlocked logs found at Kalambo Falls in Zambia date to about 476,000 years ago, long before modern humans appeared.

Context

Wood almost never survives for hundreds of thousands of years, so this find is unusual. At Kalambo Falls, near the Zambia–Tanzania border, waterlogged sediments kept the timbers from rotting. A team led by archaeologists from the University of Liverpool and Aberystwyth University found two logs that had been notched so that they fit together, and which may have formed part of a platform or walkway.

Dating relied on luminescence methods, which estimate when mineral grains in the sediment were last exposed to sunlight. The published result was at least 476,000 years, with an uncertainty of tens of thousands of years, which is why the figure is given as approximate.

The age is older than the earliest known members of our species, which appear in the fossil record at about 300,000 years ago. The builders were therefore an earlier kind of human, probably some relative such as Homo heidelbergensis, though the species is not known. The site also yielded wooden tools, which shows planned woodworking.The preservation of such delicate evidence is rare, so most of what archaeologists know about very early woodworking comes from only a handful of waterlogged sites like this one. For that reason the discovery is treated as an important but isolated data point, not as proof of how widespread such building was.