Half-million-year-old wooden structure discovered in Africa

Archaeologists have unearthed the oldest wooden structure ever fashioned by humans, nearly half a million years old, a complex construction that assumes advanced technical abilities among early humans, according to a study published Wednesday .

Exceptionally well preserved, the structure was discovered at the prehistoric site of Kalambo Falls in what is now Zambia, and dates back at least 476,000 years, before the supposed appearance of our own species, Homo sapiens. It consists of two interlocking logs, connected transversely by a notch intentionally made to build a structure, probably the foundation of a raised platform, passage or habitat, according to the study published in Nature. A collection of wooden tools, including a digging stick, was also unearthed at the site.

The use of wood by man at such ancient ages had already been proven, but for a limited use: making fire, or sharpening sticks for hunting or gathering.

The oldest wooden structure known to date dates back only 9,000 years, explains to AFP Larry Barham, professor at the British University of Liverpool, first author of the study. The archaeologist did not expect to find such a treasure while excavating the prehistoric site of Kalambo, located on the banks of the river of the same name, above waterfalls 235 meters high. “It is rare to find wood in such ancient sites because it usually rots and disappears. But at Kalambo Falls, permanently high water levels have preserved it,” the authors explain in a press release.

In the 1950s and 1960s, initial excavations had already yielded pieces of wood, without the possibility of dating them. The new pieces, discovered in 2019, revealed their age with luminescence dating of the deposits surrounding the objects - the method makes it possible to determine when they were last exposed to sunlight before being buried, details the Professor Geoff Duller of Aberystwyth University in Wales, co-author.

Verdict: the deposits are at least 476,000 years old, “which proves that this site is much older than we thought,” underlines the scientist. And that it was occupied long before Homo sapiens, whose oldest fossils date back around 300,000 years.

The research could not determine which human lineage was at work, but Professor Barham does not rule out being dealing with Homo heidelbergensis, an extinct species which lived between approximately 700,000 and 220,000 years before our era. Because apart from the fossil of a skull of Homo heidelbergensis, discovered in Zambia in the 1920s, “there is no other known hominin in the region”.

The discovery has, in any case, “changed his vision” of our first ancestors. “They used their intelligence to transform their environment and make their lives easier, if only by making a platform to sit on the banks of the river,” deciphers the archaeologist. And managed to make “something they had never seen before”: unlike the size of a stick, easily observed and imitated, the creation of two pieces with a view to their assembly shows, according to him, faculties of abstraction .

“The fact that they were able to work wood on a large scale presupposes cognitive abilities such as planning, visualizing the finished product before its conception, moving objects mentally in space,” observes prehistorian Sophie Archambault de Beaune, professor at Jean Moulin Lyon 3 University, who did not participate in the work.

“These capacities were already assumed from the study of cut stone tools”, common in these ancient times, nevertheless underlines the researcher interviewed by AFP. According to the study's authors, the structure was conducive to "sustained occupation," which "challenges the idea that these early humans were nomadic."

“At Kalambo Falls, they not only had a perennial source of water, but the forest that surrounded them provided them with enough food to allow them to settle down and build structures,” they say.

A hypothesis which remains to be proven, because it could also be “seasonal installations”, comments Sophie Archambault de Beaune.