Kalambo Falls Wooden Structure

The Kalambo Falls wooden structure is a pair of worked logs found beside the Kalambo River in Zambia, near the border with Tanzania at the southeast end of Lake Tanganyika. The two logs were joined crosswise by a notch cut on purpose, and were dated by luminescence to at least 476,000 years ago. The find was published in Nature on 20 September 2023 under the title "Evidence for the earliest structural use of wood at least 476,000 years ago".

It is not a roof, and no shelter has been reconstructed from it. Its importance for roofing history is that it pushes the earliest known deliberate joining of timbers back by hundreds of thousands of years. Roof frames of every later period, from brush huts to timber longhouses, depend on the same basic skill.

The find

• Structure: two logs fitted together; the upper one was shaped, and tool marks appear on both.
• Excavation: 2019, by a team led by Larry Barham of the University of Liverpool, with dating by Geoff Duller of Aberystwyth University.
• Dating: luminescence dating of the sand minerals around the wood. Smaller wooden objects from the site were buried about 390,000 and 324,000 years ago.
• Preservation: the wood is thought to have survived because it stayed waterlogged near the waterfall.

Interpretation

The researchers suggested the logs might have formed a raised platform, a walkway or the foundation for dwellings on a floodplain that was periodically wet. Barham described one possibility as a platform by the river for daily tasks. The structure predates the appearance of Homo sapiens, so the builders may have been an earlier hominin species, possibly Homo heidelbergensis; this attribution is speculative. The team argued the find challenges the view that Stone Age people were always on the move.

Earlier work at the site

Kalambo Falls was excavated by J. Desmond Clark in 1953, 1956, 1959 and 1963. He recovered Late Acheulean stone tools, hearths and wooden objects including a club and digging sticks, showing that the site preserves organic material unusually well.

Significance for roofing history

Wood rots quickly, so the record of early building is biased toward stone. Kalambo Falls shows that hominins were shaping and joining timber long before any surviving evidence of a roofed dwelling. Whether such skills were used for shelters at this date is unknown.