Wood has always been an important material for us humans. Now archaeologists in Zambia have discovered the oldest evidence of a prehistoric wooden structure to date. It is a thick branch with a U-shaped hollow on the underside and a tree trunk whose upper end fits exactly into this notch by narrowing it. Traces of processing indicate that this ensemble was not created by chance, but was put together by Stone Age human ancestors using stone tools and fire. At least 476,000 years old, this is the earliest known human-made wooden structure. However, what it was used for and who built it is still unknown.
Many archaeological finds prove that the first representatives of our genus, including Homo habilis and Homo erectus, made and used stone tools. Pre-humans from the time of Australopithecus may have already made the first simple stone tools, as finds more than 2.5 million years old in Kenya suggest. Prehistoric weapons or tools made of wood, on the other hand, are significantly sparser and younger because they rarely last for thousands of years. “As a result, we have limited information about when and how hominins used this raw material,” explain Larry Barham from the University of Liverpool and his colleagues. The oldest wooden tools that have been clearly dated to date include the throwing sticks and wooden spears from Schöningen in Lower Saxony, which are around 300,000 years old and probably come from Homo heidelbergensis. In Africa, a sharpened wooden stick that is around 250,000 years old was the oldest surviving evidence of early human woodworking.
T-shaped connection of two wooden beams
New finds from Zambia now prove that our ancestors began using wood for more than just fuel much earlier. Barham and his team discovered evidence of this above the Kalambo waterfall in Zambia. There, shortly before the river flows into Lake Tanganyika, archaeologists had already discovered potential traces of early human presence in the 1950s and 1960s. During new excavations at this site, Barham and his colleagues now came across five additional pieces of wood that show traces of processing. Determining the age using luminescence dating of the respective layers of finds showed that these wooden objects are between 476,000 and 322,000 years old. The two oldest finds lay beneath the surface of the water and formed an ensemble of a 1.41 meter long beam that lay across the end of a larger tree trunk.
Closer examination revealed that a U-shaped cavity about eleven centimeters wide was notched on the underside of the upper beam. “The tree trunk underneath is also processed and fits into this notch,” report the researchers. Both pieces of wood sit together as if they were joined together with a tenon and notch. “Traces of chopping and scraping can be seen on the surface of the notch,” the archaeologists continued. Some of these form strikingly parallel lines that run across the grain. Infrared spectroscopy revealed that fire was also used to hollow out the notch. Barham and his team also discovered similar traces of processing on the area of the tree trunk near the crossbeam. There were also numerous grooves running transversely to the grain direction, and some also had V-shaped traces.
Earliest evidence of a man-made wooden structure
According to archaeologists, these traces indicate that these two pieces of wood were worked with stone tools and by human hands. “We interpret the notch as being created intentionally, by scraping and chopping to create a connection between the branch and the trunk, forming a structure of two connected parts,” explain Barham and his colleagues. “The two finds demonstrate a core concept of building: the combination of two or more components to form a structure.” This means that this wooden structure, which is more than 476,000 years old, could be one of the earliest evidence of human woodworking – and the oldest wooden structure in the world to date. “This construction is unique; there is nothing comparable in the African or Eurasian Paleolithic,” said the team.
However, it is unclear what the purpose of connecting the two wooden parts was. The archaeologists suspect that the finds could have originally been part of some kind of platform, a path fortification or a dwelling. This may have made life easier for them in the humid and possibly more frequently flooded environment along the river. “These people changed their environment to make their lives easier, even if it was just a platform on which they could sit on the riverbank and do their daily chores,” says Barham. "This discovery makes me think differently about our early ancestors; they were more similar to us than you think: they used their intelligence, imagination and skills to create something that didn't exist before." In an accompanying commentary in Nature Writes archaeologist Annemieke Mills of the University of Reading, who was not involved in the study: “Studies like this underline the role that this humble material played in human history, while also revealing when humans began to reshape the planet for their own purposes .”
Source: Lawrence Barham (University of Liverpool) et al., Nature, doi: 10.1038/s41586-023-06557-9)