Humans older than thought?

(January 1997)

One way of defining humans is to call them "tool-making animals". Birds may use thorns, chimpanzees may use sticks, but only humans actually change and modify and make tools from other things, say most scientists.

On that basis, "made" tools are by definition the work of members of the genus Homo, but now there is evidence of Oldowan-style tools, reliably dated to 2.5 - 2.6 Myr (million years). The Oldowan Stone tool industry was named for 1.8-million-year-old (Myr) artifacts found near the bottom of Olduvai Gorge, Tanzania. Later archaeological research in the Omo (Ethiopia) and Turkana (Kenya) also yielded stone tools dated to 2.3 Myr. Until the recent find, this seemed to fit with the earliest dates for bones and teeth which showed all the signs of coming from Homo, and so all was well.

These new occurrences are now securely dated between by several means, making the stone tools the oldest known artifacts from anywhere in the world. The artifacts are described as showing surprisingly sophisticated control of stone fracture mechanics, equivalent to much younger Oldowan assemblages.

So either Homo is older than we thought, or, as some scientists are now suggesting, the Oldowan tools were made by the robust Australopithecines, generally now referred to as Paranthropus robustus and Paranthropus boisei. If that is the case, then humans were not the only tool makers.