Archaeologists working in the Kenyan Rift Valley have discovered the oldest known stone tools in the world. Dated to around 3.3 million years ago, the implements are some 700,000 years older than stone tools from Ethiopia that previously held this distinction. They are so old, in fact, that they predate the earliest fossils representing our genus, Homo, by half a million years. As such they suggest that stone tool manufacture began not with Homo, but with a more primitive member of the human family.
The Turkana Basin Institute (TBI) created 3-D laser scans of the Lomekwi 3 tools to reveal very fine details on their surfaces. “The tools are much larger than later Oldowan tools, and we can see from the scars left on them when they were being made that the techniques used were more rudimentary, requiring holding the stone in two hands or resting the stone on an anvil when hitting it with a hammerstone,” said Sonia Harmand of TBI.
The tools from Lomekwi 3 are quite large—larger than the stone tools from the site of Gona in Ethiopia that were previously the oldest on record and larger than the rocks that chimpanzees use to crack open nuts. According to Harmand, preliminary observations suggest that the Lomekwi toolmakers intentionally selected big, heavy blocks of very hard raw material from nearby sources even though smaller blocks were available. They used various knapping techniques to remove the sharp-edged flakes from the cores.
Exactly what the Lomekwi knappers used their tools for is not yet clear. Animal bones recovered thus far at the site do not show any signs of human activity. But evidence from another site does suggest that hominins (the group that includes H. sapiens and its extinct relatives) were butchering animals back then.
Although very recent research has now pushed back the origins of the genus Homo to as early as 2.8 million years ago, the tools are too old to have been made by the first fully fledged humans, Harmand said in her talk. The most likely explanation, she concluded, was that the artifacts were made either by australopithecines similar to Lucy or by Kenyanthropus. Either way, toolmaking apparently began before the birth of our genus. Harmand and her colleagues propose to call the new tools the Lomekwian technology, she said, because they are too old and too distinct from Oldowan implements to represent the same technology.