source： editor：Zhang Wenni
An excavation team uncovers the world's oldest wooden structure found on a riverbed near a waterfall in Zambia. LARRY BARHAM/AP
PARIS — Archaeologists said on Wednesday they have unearthed the oldest wooden structure ever discovered, dating from nearly half a million years ago, which suggests that our ancestors may have been more advanced than previously thought.
The exceptionally well-preserved wooden structure was found at Kalambo Falls in the north of Zambia near the border with Tanzania.
It dates back at least 476,000 years, well before the evolution of Homo sapiens, according to a study describing the find in the journal Nature.
The wood bears cut marks showing that stone tools were used to join two large logs to make the structure, which is believed to be a walkway or platform raised above the seasonally wet surroundings.
A collection of wooden tools, including a wedge and a digging stick, were also discovered at the site.
The ancestors of humans were already known to use wood at this time, but for limited purposes such as starting a fire or hunting.
"The structure involves the intentional shaping of two trees to create a framework of two interlocking supports," Larry Barham, an archaeologist at the University of Liverpool in England and the study's lead author, said. "A notch was cut into the overlying log and the underlying tree was shaped to fit through the notch. This arrangement prevents the overlying log from moving side to side, giving stability to the structure."
Discoveries involving such ancient wood are rare because it tends to rot, leaving behind little trace for historical record.
But the high level of water at Kalambo Falls is believed to have preserved the structure over the centuries.
"The finds from Kalambo Falls indicate that these hominins, like Homo sapiens, had the capacity to alter their surroundings, creating a built environment," Barham said. "Use of wood in this way suggests the cognitive ability to these early humans was greater than we have believed based on stone tools alone."
Agencies via Xinhua