Researchers sifting through the Ethiopian desert have uncovered the oldest stone tools ever found. The discovery has touched off what may be the oldest whodunit yet.
Dating to 2.6 million years ago, the tools are 200,000 to 300,000 years older than the previous recordholders. The artifacts, found in the Gona River area of Ethiopia's Awash Valley, include fist-size cobbles that served as a source for flakes, sharp-edged flakes, and flake fragments.
The interest in early tools stems from their use as markers for evolution in early human behavior, according to Sileshi Semaw, an Ethiopian paleoanthropologist. Mr. Semaw is the lead author of a research paper summarizing the results in the current issue of the journal Nature.
"Surprisingly for this early date, the toolmakers had a clear understanding of producing sharp-edged tools," adds Jack Harris, chairman of the anthropology department at Rutgers University in New Brunswick, N.J., who is a coauthor of the paper.
Semaw, who is to receive his doctorate from Rutgers in May, notes that anthropologists hold that roughly 2 million years passed between the time early humans began to walk upright and the first appearance of sharp-edged tools.
Harris says the discoveries may suggest that the genus Homo, which includes modern humans as well as extinct related species, emerged earlier than previously believed. "That in itself is a thrilling thought," he said last week.
The Gona tools bear a remarkable resemblance to those found in Tanzania's Olduvai Gorge in the late 1960s, the researchers say. These younger artifacts, discovered by the late Mary Leakey, date to between 1.7 million and 1.8 million years ago. Semaw says he finds it amazing that "the earliest human technology" remained unchanged for nearly a million years.
Some question whether the toolmakers were indeed early humans. Bernard Wood, of the University of Liverpool, suggests that Paranthropus boisei, a cousin of early Homo, is an equally likely candidate. This species had the dexterity and intelligence to make tools, he writes in Nature, and unlike the various species of Homo that rose and fell over the million years, Paranthropus lived throughout the period.