Homo were not yet sapiens that they were already working to build. A team of archaeologists exhumed the remains of a wooden structure at the site of Kalambo Falls in Zambia in 2019. These remains, unveiled this Wednesday in the columns of the journal Nature, would date back 476,000 years, which would make it the oldest known construction made from this material, while our species had not yet appeared.
What we learn from an early age in "The Three Little Pigs" is that the wooden house is not the most resistant to the onslaught of the wolf. Similarly, it is very difficult to find wooden objects as old as those of Kalambo, because they require exceptional conservation conditions. Also, the history of the use of trees is not well known. Wooden spears dating back 400,000 years have just been found in the United Kingdom. At the Zambian excavation site, however, high water levels would have preserved the logs from degradation and decay.
Researchers say that ancient humans would have assembled there, in this regularly flooded plain, two large logs to form a structure, probably the foundation of a platform, a footbridge or part of a dwelling. The logs have been "shaped to fit around a notch," Nature says, and feature tool marks. A collection of wooden tools was found nearby.
The energy of grains of sand
To date the pieces of wood, scientists at Aberystwyth University in Wales used so-called luminescence techniques. The trick was to define when the minerals surrounding the logs last saw sunlight.
"The sand that made up these sediments is made up of common minerals like quartz and feldspar. They have the particularity of being able to store energy within their structure," explains Geoff Duller, co-author of the article. Grains of sand derive this energy from the radioactive decay of elements such as uranium, thorium and potassium in the soil. "The longer the grains of sand are buried, the more energy they store," Duller continues. On the other hand, this energy disappears as soon as the minerals take light.
This discovery would challenge the idea that our Stone Age ancestors were necessarily nomadic. The favourable environment of Kalambo Falls, with permanently available water and a forest teeming with food, would have prompted some to put their bundles there. Researchers do not venture to say which homo species would be at the origin of the wooden construction.
This work would also suggest rewriting the history of tree use. In a statement, Larry Barham, the lead author of the study, professor at the University of Liverpool (United Kingdom), enthused: "This discovery has changed the way I see our distant ancestors. Forget the Stone Age label, look at what these people did: they made something new, and massive, out of wood. They used their intelligence, imagination, and skills to create something they had never seen before, something that had never existed before. »