Archaeologists in Kenya have uncovered some of the oldest-known stone tools in the world along the banks of Lake Victoria, thus toppling Ethiopia as the oldest site of early stone technology.
Writing in the current issue of the journal Science, the scientists say that the stone tools found in the Homa Bay site were likely made about three million years ago compared to the previously known oldest examples dating 2.6 million years from Ethiopia’s Ledi-Gararu site.
The archaeologists also found teeth of Paranthropus, a “muscular-jawed ape-like individual”. They say this is the first time this particular genus is being associated with stone tools.
Paranthropus was an upright walking species roaming the African savannah before it became extinct. Since it is not regarded as a direct ancestor to modern-day humans, its association with stone tools has thrown scientists back to the drawing board to figure out whether two genera living at the same time made similar stone tools.
“The assumption among researchers has long been that only the genus Homo, to which humans belong, was capable of making stone tools,” said Prof Rick Potts, a senior author of the study. “But finding Paranthropus alongside these stone tools opens up a fascinating whodunit.”
New evidence
Thus, the Nyayanga site in Homa Bay brought new evidence of another genus associated with stone tools.
Since the Kenya and Ethiopian sites are 1,300 kilometres apart, archaeologists are not only excited about the spread of the Oldowan stone technology – named after Tanzania’s Olduvai Gorge, where this technology was discovered first by Dr Mary Leakey in 1971 – but about how human ancestors adapted to the changing environment, giving rise to the human species.
“This is one of the oldest if not the oldest example of Oldowan technology,” said Thomas Plummer, the study’s lead author. “This shows the toolkit was more widely distributed at earlier dates than people realised, and that it was used to process a wide variety of plant and animal tissues.”
In the years to come, attention might shift to these Homa Bay sites to see whether they could yield evidence of a genus in the human lineage using similar stone tools. Of interest is that the massive Paranthropus molars that were discovered at the site are the oldest known from that species. This has brought the Lake Victoria region back in the circuit of archaeologists and palaeontologists eager to find the missing links in the human evolution puzzle. Attention had previously shifted to Turkana and Marsabit counties.
The Oldowan stone tools discovered at the site include hammer stones, cores and flakes. Scientists say the hammer stones were used to hit other rocks to create tools or for pounding other materials. The cores, when struck at an angle with the hammer stone, were used to split pieces, while flakes were used to either cut or scrap.
‘New variety of foods’
“With these tools you can crush better than an elephant’s molar can and cut better than a lion’s canine can,” said Prof Potts. “Oldowan technology was like suddenly evolving a brand-new set of teeth outside your body, and it opened up a new variety of foods on the African savannah to our ancestors.” According to researchers, the technology upgrade required skills, and is associated with an expansion of intelligence.
The Homa Bay site was first brought to the attention of scientists in 2015 by a local, Peter Onyango, who suggested to a team of palaeontologists investigating sites with large numbers of fossilised baboon-like monkeys to also look at a nearby site with protruding stone tools.
When the site was first excavated, it yielded 3,330 artefacts and 1,776 animal bones, including the two Paranthropus teeth. Alongside the stone tools were three hippos, and two exhibited signs of butchery using them.
“The team found a deep cut mark on one of the hippo’s rib fragment and a series of four short, parallel cuts on the shin bone of another,” said Dr Plummer.
Archaeologists are similarly puzzled at how Oldowan technology spread across Africa, towards China and modern-day Georgia. More so, they seek to understand why it dominated the scene for over one million years until it was replaced by hand axes some 1.7 million years ago. The hand axes are associated with Homo erectus. And since Homo erectus did not evolve from Paranthropus, the Homa Bay findings have brought another puzzle in the search for the missing link.
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