Archaeologists have uncovered evidence of the oldest wooden structure on record: a pair of interlocking logs connected by a notch that date to 476,000 years ago.
Discovered along the Kalambo River in Zambia, the simple construction predates the first appearance of Homo sapiens in Africa. The discovery, detailed in a new paper published Wednesday in Nature, suggests human ancestors built structures made of wood and may have been more complex than previously thought.
“This is a disruptive discovery,” Larry Barham, a co-author of the new study and an archaeologist at the University of Liverpool in England, tells Scientific American’s Tom Metcalfe. “I never would have thought that pre-Homo sapiens would have had the capacity to plan something like this.”
“It’s an important window into what these humans were capable of,” Annemieke Milks, an archaeologist at the University of Reading in England who did not contribute to the research, tells Maddie Burakoff of the Associated Press (AP).
Wooden artifacts typically don’t survive for millennia because they break down, disappearing from the historical record if they’re not well-preserved. But in this case, the researchers think that water may have protected the wood, which was discovered near a waterfall, per the Agence France-Presse (AFP).
“I think most early human groups would have been using wood in some form,” Milks tells the New York Times’ Carl Zimmer. “We just don’t see it.”
If prehistoric wood was preserved as well as stone and bone, “we would probably use the term ‘wood age’ rather than Stone Age,” Barham tells Nature News’ Ewen Callaway.
Scientists have previously discovered less complex uses of wood from this time period. The earliest known wooden artifact, a piece of a polished plank found in Israel, dates to more than 780,000 years ago, per the new paper. And archaeologists have dug up 400,000-year-old wooden tools for foraging and hunting from around the world.
But before this new find, the oldest known structure made of wood was only 9,000 years old, Barham tells the AFP.
In the 1950s and 1960s, researchers recovered ancient wood that may have been intentionally modified at Kalambo Falls, the site of the new study, but they were unable to precisely date the artifacts.
Excavations for the new study took place in 2019. In the sediment near the Kalambo River, the team found five wooden objects with signs of modification. They uncovered a sharpened tip that fit on the end of a stick discovered nearby, writes the New York Times. Some of the other objects could have been used for digging or as a wedge, per Nature News.
To date these objects, the researchers analyzed minerals in the sand that surrounded them through a technique called luminescence dating, Geoff Duller, a co-author of the study and dating expert at Aberystwyth University in Wales, tells the AP. The smaller wooden objects were buried around 390,000 and 324,000 years ago.
But the biggest finding was the pair of logs, which had been shaped so they could fit together like Lincoln Logs, the children’s building toys. Barham theorizes the wood could have been part of a platform for fishing or some other raised surface above the muddy ground, according to Nature News.
“It took me a while before I appreciated what we were looking at,” Barham tells the AP. “It didn’t look very nice, to be honest. But it is much more complex than I thought.”
Biancamaria Aranguren, an archaeologist who wasn’t involved in the research, tells Scientific American that researchers should study waterlogged sites more, since this finding shows these areas could preserve evidence of woodworking.
“Our knowledge about the use and the processing of wood in the most ancient periods of prehistory is comparable to the tip of an iceberg,” Aranguren tells the publication.