On the banks of the Kalambo River in Zambia, archaeologists have made a discovery that may change our understanding of ancient life in Africa. Two interlocking logs that date back 476,000 years show clear signs of woodworking. It is the oldest known wooden structure in the world.
The logs, which came from a large-fruited bushwillow tree, have notches carved into their ends. Archaeologists found nearby tools, such as axes, that could have done this cutting and scraping.
The researchers found a number of other items at the site, including a wedge, a digging stick, and a chopping block. All date between 324,000 and 390,000 years ago. It means that woodworking pre-dates the evolution of Homo sapiens by over 100,000 years.
Made before Homo sapiens
The unknown structure was likely made by Homo heidelbergensis. The common ancestor of Homo sapiens and Neanderthals, heidelbergensis lived between 200,000 and 700,000 years ago. No human remains have ever turned up at the Kalambo Falls site, but a Homo heidelbergensis skull was found previously in Zambia.
Researchers in the 1950s and 1960s also found wooden and stone artifacts at the site that may have been tools. At the time, technology did not allow them to accurately date the objects.
Decades later, a team led by Larry Barham went back to the site. Using new techniques, they scoured for stone tools.
“We didn’t expect to find wood,” said Barham. “This find has changed how I think about our early ancestors.”
In 2019, they saw a large chunk of wood sticking out of a cliff face and began to dig it out. A number of wood pieces were within the waterlogged river bank. Two of the logs showed clear signs that they had been carved so that they could be stacked and interlocked. “They were building something which was ― at least in one direction ― stable,” said Barham.
The underlying log passes through a central notch cut into the upper log. Image: Barham et al., 2023
How its age was determined
The new study used luminescence dating to figure out how old the wood is. Over time, minerals in the earth absorb background radiation. By measuring the radioactivity in the minerals that surrounded the wood, they were able to decipher when the pieces were last exposed to sunlight. In turn, that indicates how old it is.
Understanding how our ancient ancestors used wood is incredibly difficult. It decomposes so easily that it is hard to create any type of archaeological record of it. This shows that ancient humans built structures.
“When I first saw it, I thought this can’t be real. The wood and the stone suggest a high level of ingenuity, technological skill, and planning,” said Barham.
Archaeologists uncover remnants of a wooden structure in Zambia. Photo: Larry Barham/University of Liverpool
Before this, we only had evidence that wood was used for tools and fires during this time period. The earliest known wooden artifact is a polished plank from Israel that dates back 780,000 years. Until now, the earliest example of a wooden structure dates back just 11,000 years.
