Researchers claim to have discovered the oldest human tools in Africa, dating back 3.3 million years - several hundred thousand years before our genus Homo hit the scene.
The stone flakes found are 700,000 years older than the oldest-known tools to date, researchers said.
Until now, the earliest known stone tools had been found at the site of Gona in Ethiopia and were dated to 2.6 million years ago.
In 2010, researchers working at the site of Dikika in Ethiopia reported cut marks on animal bones dated to 3.4 million years ago; they argued that tool-using human ancestors made the linear marks, 'Science Magazine' reported.
However, the claim was immediately controversial and some argued that what seemed to be cut marks might have been the result of trampling by humans or other animals.
At the annual meeting of the Paleoanthropology Society San Francisco, California, archaeologist Sonia Harmand of Stony Brook University in New York described the discovery of numerous tools at the site of Lomekwi 3, just west of Lake Turkana in Kenya.
In 2011, Harmand's team stumbled upon an area, called Lomekwi, near where a controversial human relative called Kenyanthropus platyops had been found.
The researchers spotted what Harmand called unmistakable stone tools on the surface of the sandy landscape and immediately launched a small excavation.
More tools were discovered under the ground, including so-called cores from which human ancestors struck off sharp flakes.
Researchers have now uncovered nearly 20 well-preserved flakes, cores, and anvils apparently used to hold the cores as the flakes were struck off, all sealed in sediments that provided a secure context for dating.
An additional 130 pieces have also been found on the surface, researchers said.
