Nearly half a million years ago, humans in Africa were gathering wood to create large structures, according to A Stady Published on Wednesday describes jagged and pointed tree trunks buried under sand in Zambia.
This discovery significantly advances the historical record of structural woodworking. Before, the oldest known examples of this craft were 9,000-year-old platforms on the edge of a British lake.
Ancient wood products are extremely rare because organic materials typically decompose over thousands of years, said Anneke Melkes, an archaeologist at the University of Reading, who was not involved in the new study that appeared in the journal Nature. “He almost never memorizes,” she said.
It is not clear what early humans were building in Africa. Dr Milks said the new discovery suggests they used the wood not only to make spears or digging sticks, but also in more ambitious creations such as platforms or walkways.
“I think most early human groups used wood in some form,” she said. “We just don’t see it.”
An international team of scientists discovered the tree trunks in 2019 near a huge waterfall in Zambia known as Kalambo Falls. There, the Kalambo River drops 770 feet before flowing into Lake Tanganyika.
For archaeologists, the site has a checkered history. In the 1950s, British archaeologist Desmond Clark found ancient stone tools near the waterfalls, as well as pieces of wood that he suggested were used for digging sticks and spears. Other pieces looked like they were burned. It would have been some of the earliest evidence of people setting fires.
However, by the early 2000s, much of the luster of Dr. Clark’s discovery had worn off. For one thing, he never obtained a consistent determination of the age of wood. The only reliable method available at the time for determining age was radiocarbon dating, which could only be used on objects less than 50,000 years old. The logs at Kalambo Falls have been proven to be even older, but how old are they?
Other researchers wondered whether people actually made wooden objects. Dr. Clark admitted that they were probably branches that had fallen into the Kalambo River and were reshaped by sand grains carried in the water flowing towards the falls.
In 2006, Lawrence Parham, an archaeologist at the University of Liverpool, and his colleagues returned to Kalambo Falls. By then, researchers had developed a new method for determining the age of archaeological sites, taking advantage of the way quartz grains could function like geological clocks. When uranium atoms naturally found in the Earth decay, they release energy that is trapped within the quartz. Over time, the grains store more and more energy, which scientists can later measure in their laboratories. The higher the energy, the older the sample.
On their trip to Kalambo Falls in 2006, scientists found more stone tools. Geoff Dowler, a geophysicist at Aberystwyth University in Wales, collected sand from river banks and spent the next few years measuring the energy trapped in it. . He concluded that the oldest sediment layers containing stone tools are between 300,000 and 500,000 years old.
This means that tools were made long before modern humans evolved. Scientists suspect they may have been made by an earlier species found in Zambia, known as Homo heidelbergensis.
The researchers made another trip to the falls, in 2019, and Dr. Dowler had planned to use a more robust dating technique based on feldspar grains rather than quartz.
But when they arrived at Dr. Clark’s old location, they discovered that he had disappeared. In the 13 years since their last journey, the river has turned away. All that remained was a swamp filled with reeds.
Fortunately, Dr. Barham prepared an alternative plan. Before the expedition, he used Google Earth to identify a promising strip of beach along the Kalambo River. When they got there, Dr. Barham immediately saw a stick sticking out of the sand. In the water, he found a sharp tip that fit perfectly on one end of the stick. Had he come a year later, the fragments might have been swept away. “It was just a lucky moment,” Dr. Barham said.
In the same area, researchers found stone tools along with wood in the shape of wedges and the letter V, which are clear signs of manual labor.
Dr. Dowler used feldspar grains to determine the age of the artifacts. He found that the objects came from three different eras: 487,000 years ago, 390,000 years ago, and 324,000 years ago. It is likely that people lived by the river throughout that period or returned to it over thousands of generations.
At the end of the field season in 2019, researchers made their most exciting discovery. In the oldest layer of sand, they discovered a four-and-a-half-foot-tall tree trunk from a small African tree known as Zaheer shrub. Near the pointed end of the log, researchers noticed a large notch. As they dug further, they realized that the excavated portion of the tree trunk was resting on the trunk of a larger tree.
When the researchers uncovered the wood, they took high-resolution images. The images revealed chopping marks on the trunk and torso, indicating that people used axes and scraping tools. “This is intentional,” Dr. Barham said. “This is intentional.”
Dr Milks said taking photographs of ancient wooden objects as soon as they were discovered was crucial to understanding how they were made. The waterlogged sand allowed the wood to survive hundreds of thousands of years virtually unchanged. But when old wood is exposed to air again, it can lose essential evidence within minutes. “It can shrink, it can twist, all kinds of things can happen,” Dr. Milks said.
Dr Barham and his colleagues collaborated with John Mukuba, a traditional Zambian woodworker, to interpret their findings. They suspect that people cut down living trees with stone axes. They then worked on the wood so that the two pieces could fit together into a larger structure.
Dr. Barham speculated that the torso and torso were part of a structure built over the swampy ground along the Kalambo River. “It’s about keeping your feet dry, keeping your food dry, or keeping your firewood dry,” he said.
“Put yourself in the mind of someone who lived there approximately 480,000 years ago and had a great mind,” he said. “Don’t be afraid of complex suggestions.”
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