Who invented stone tools? A great surprise from Kenya

Up to now the earliest stone tools are objects dated to about 3.3 Ma (Late Pliocene) found in the Turkana basin of Kenya in 2015. They are sharp-edged pieces of rock that seem to have been made simply by striking two lumps of rock together (see: Stone tools go even further back; May 2015). These Lomekwian artefacts are similar to the basic tools made today by some chimpanzees in parts of Africa. Their age matches that for the earliest known animal bones that show signs of having meat cut from them, which were unearthed in Dikika, Ethiopia (see: Another big surprise; September 2010) which, like the Lomekwian tools, are not accompanied by tools or hominin remains. The earliest tools associated with members of the genus Homo are significantly more sophisticated. They were found in close association with H. habilis at what seems to have been a well-used butchering site, dated at 2.0 Ma, in Tanzania’s Olduvai Gorge, hence their designation as the Oldowan ‘industry’. The Oldowan ‘tool kit’ includes choppers and blades deliberately shaped to be wielded by hand and made by striking large cobbles with distinctive hammer stones. Earlier tools with this level of deliberate crafting come from the 2.6 Ma Ledi-Geraru site in the Afar Depression of NE Ethiopia but with no sign of their makers.

Oldowan tools used for pounding and cutting from Nyayanga, Kenya (Credit: Thomas Plummer, James Oliver and Emma Finestone/Homa Peninsula Paleoanthropology Project/SWNS)

The presence of Oldowan tools has now been pushed further back, by about 400 ka, thanks to excavations in Late Pliocene sediments at Nyayanga on the shore of Lake Victoria in western Kenya by Thomas Plummer of Queens College in New York State, USA, and his numerous collaborators from the US, Germany, the UK, China, Italy, Australia, Kenya, South Africa and Poland (Plummer, T.W. and 31 others 2023. Expanded geographic distribution and dietary strategies of the earliest Oldowan hominins and Paranthropus. Science, v. 379, p. 561-566; DOI: 10.1126/science.abo7452). Their work also expands the range of Oldowan culture by about 1300 km. The Nyayanga site yielded over 300 artefacts that closely resemble the previously known range of Oldowan tool shapes. Their makers struck flakes from suitable corestones – made of rhyolite, quartz and quartzite – and trimmed them by more intricate means. They seem to have been used to cut up mainly hippo and buffalo, bones of which bear clear cut marks, but had other uses. Analysis of the wear on tool surfaces not only show signs of butchery, but also processing of plant tissue by pounding; the latter resulted in pitting and polishing of tools that seem to have been used many times. Stable-isotope analysis of the bones and animal teeth suggests that in the Pliocene Nyayanga was a grassy and partly wooded savannah close to a substantial water body needed by hippos.

Reconstruction of a Paranthropus head (Credit: Jerry Humphrey, Pinterest)

The ‘great surprise’ is that the only hominin remains associated with the site are two damaged molar teeth. They are so large that their most likely source was a species of Paranthropus.Paranthropoids have long been considered to be a gorilla-like, ‘robust’ branch of australopithecines. Their large cranial crests anchoring jaw muscles and enormous teeth were reckoned to indicate a diet of tough vegetation – the discoverer of the first specimen of P. boisei dubbed it ‘Nutcracker Man’ – although the wear on individual teeth suggests otherwise. But there is no reason to suppose that they could not eat meat. They survived australopithecines by more than a million years to cohabit the East African savannahs with H. ergaster until about 1 Ma ago.

Lead author Thomas Plummer wonders if paranthropoids would have needed tools because they had the largest jaws and teeth of any hominin. But had his team found close association with smaller H.habilis teeth would he have held a similarly negative view? There is evidence from younger sites in South Africa that paranthropoids used a wide diversity of bone tools and may even have been among the earliest fire users. So why the negativity about stone tools? To paraphrase Ali G, ‘Is it because they is ugly?’

See also: Devlin, H, Discovery of 3m-year-old stone tools sparks prehistoric whodunit. The Guardian, 9 February 2023

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