Scientists have discovered stone tools in Ethiopia that appear to be 2.6 million years old, making them the "oldest known artifacts from anywhere in the world," says Rutgers University paleoanthropologist Sileshi Semaw. The find, reported in tomorrow's issue of Nature, pushes back the earliest manufacture of tools by at least 250,000 years to a time when the first members of our genus, Homo, were thought to have been born in Africa.
Semaw's group unearthed the 3000 stone tools from the Gona River drainage basin of the fossil-rich Awash River Valley, from a soil layer dated with a new method called argon-argon single-crystal laser fusion. The artifacts range from thumb-sized flakes to fist-sized cobbles; experts speculate that the tools may have been used for cutting flesh or digging for food. They are surprisingly sophisticated, says University of Liverpool paleoanthropologist Bernard Wood--especially because some researchers doubted that humans had evolved enough to make tools before 2 million years ago. But the manufacturers of the Gona River trove had learned how to fashion tools with sharp edges--a hallmark of the Oldowan style that persisted with little change until about 1.6 million years ago.
Who made them? One clue comes from a site close by at Hadar, where similar Oldowan tools were found in 1994 near the 2.3-million-year-old upper jaw of what is probably an early member of the genus Homo (Science, 22 November 1996, p. 1298 ). Semaw and other paleoanthropologists plan to return to Gona this year to look for fossilized remains of individuals who might have made the world's oldest tools. But even fossils may not clear up that question, says Wood: At least three different genera of early humans were alive at the time.
For more information on the find, visit Rutgers's Web site