Earliest stone tools found in Kenya

3.3-million-year-old tool tradition significantly predates first humans

In recent years, a growing body of evidence has suggested that the making of stone tools predates the emergence of the earliest humans. In the 1990s, Oldowan-type tools dating to around 2.6 million years ago were found at the Gona River study area in Ethiopia. The tools slightly predated the then-earliest known humans, but as they were not associated with hominin remains there was no way of telling who the toolmakers had been. Towards the end of the decade, evidence of carcass butchery dating to around 2.5 million years ago was found at the nearby Bouri Formation. Bones of large mammals with cut-marks thought to be made by stone tools in the process of de-fleshing the carcasses were associated with australopithecine remains. Unfortunately, on this occasion, no actual stone tools were found.

Similarly, in 2010, it was claimed that animal bones from Dikika, Ethiopia, show cut-marks resulting from de-fleshing, and signs of having been struck with hammerstones to extract bone marrow. The remains are 3.39 million years old, early enough to preclude human involvement – but again no actual tools were found. It could not be ruled out that naturally-occurring sharp pieces of stone had been used. It is also possible that as the bones were buried in coarse-grained, sandy deposits, trampling by animals could have produced the marks. Taken as a whole, these finds made a good case for australopithecine tool making, but did not settle matters beyond reasonable doubt. Conclusive evidence was still lacking.

Such evidence has now been reported from the Kenya site of Lomekwi 3, just west of Lake Turkana. More than one hundred stone artefacts have been recovered, and at 3.3 million years old they predate even the recently-reported LD 350-1 human jawbone by half a million years. The artefacts include flakes and the cores from which they were struck. It has been shown that the cores were rotated as successive flakes were struck off, confirming that the flaking was intentional and not the result of accidental fracturing. Researchers have also managed to ‘refit’ one of the flakes back to the core from which it was struck. The tools are larger and heavier than typical Oldowan artefacts, and methods by which flakes were struck from cores was less effective. It is suggested that they represent a technology intermediate between the use of stone tools for pounding and hammering and the more flake-orientated Oldowan.

This pre-Oldowan technology has been named Lomekwian and is the final proof that hominins contemporary with Australopithecus afarensis (‘Lucy’s’ people) were making stone tools.

Reference:
Harmand, S. et al., 3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya. Nature 521, 310-315 (2015).