When our ancestors began using stone tools, it was a major step forward in their cultural and intellectual development. The invention of Oldowan tool technology is considered particularly important. Researchers in western Kenya have now discovered the oldest evidence of this Oldowan culture to date: around 2.9 million years old stone tools with signs of wear that reveal their use for carving up large game and preparing plants. Two teeth of a Paranthropus pre-human discovered at the same site also raise the question of whether this tool technology may not have been developed by early humans of the genus Homo, but rather by their predecessors.
As early as 3.3 million years ago, pre-humans cut stones into simple stone tools, as evidenced by finds on Lake Turkana in Kenya. However, these first tools were still unwieldy and crude. They were made by hitting a boulder against a bed of rock until it had a few sharp edges. In contrast, the Oldowan technique represented a real leap forward. It comprised three different types of tools that were made by hitting two hand-held stones together. A hammer stone served as a striking tool, with which fine chips were selectively and systematically separated from the second stone. The flakes then served as blades and knives, while the oval, also sharp-edged leftover stone could be used as a scraper or axe.
2.9 million year old stone tools
"Oldowan technology suddenly opened up new ways for our ancestors to obtain food," explains senior author Richard Potts of the National Museum of Natural History in Washington DC. However, it is unclear when our ancestors first reached this milestone in tool development and which pre-human or early human species invented the Oldowan tools. The oldest Oldowan stone tools to date were discovered in 2019 near Ledi-Geraru in the Afar region of Ethiopia. They are around 2.6 million years old and come from near a site where early representatives of the genus Homo were found. However, whether these early humans were the creators of these tools and how they used them cannot be clearly inferred from the finds in Ethiopia. The only thing that is clear is that the Oldowan technology spread relatively quickly across Africa and later even to Asia. It was not until about 1.7 million years ago that it was gradually replaced by the even more sophisticated hand axes of Acheulean technology.
New insights into the Oldowan technology and its origins are now provided by discoveries made by the team led by Potts and first author Thomas Plummer from Queens College in New York on the southern shore of Lake Victoria in Kenya. During excavations in Nyayanga on the Homa Peninsula, which have been ongoing since 2015, scientists have discovered more than 330 stone tools made of quartz, quartzite, granite and other rocks, including all three tool shapes typical of the Oldowan culture. "The technological characteristics of these tools, such as the sizes of the flakes and cores and the number of flake marks on the rock cores, are similar to those found in other Oldowan finds," report Plummer and his colleagues. Dating using a variety of different methods has found these stone tools to be between 2.58 and 3 million years old, with a likely age of around 2.9 million years. "This is one of the oldest, if not the oldest, testament to Oldowan technology," says Plummer.
Signs of wear and two pre-human teeth
Closer analysis revealed that many of the tools found in Nyayanga show signs of wear. Pits and scratches on the hammer stones as well as tiny plant remains in the bumps indicate that they were used to crush various food plants, including roots, fruits and leaves, but also harder plant parts. Other stone tools have been discovered in close proximity to animal bones, the scientists report. In total, they found 1,776 bones from mostly larger animals at Nyayanga, including hippopotamuses, primordial horses, saber-toothed cats and reed rats (Thryonomyidae), a group of porcupine-like rodents. On some of these bones cut and blow marks were preserved, which indicate that the pre-humans or early humans who were once present at this site must have slaughtered these animals. They probably used their tools to cut and scrape the flesh from the bones and crush the leg bones to get to the nutritious bone marrow. "This shows that the Oldowan toolkit has been used to process a wide variety of plant and animal foods," says Plummer.
The excavations also provided a first clue as to who might have made these stone tools around 2.9 million years ago. Because among the tools, the scientists also discovered two molars of a pre-human of the genus Paranthropus. This is considered to be a relative or descendant of the australopithecines, but was significantly more robust and stronger than them. "Until now, researchers have assumed that Oldowan technology was invented by the genus Homo," says Potts. "But the discovery of the Paranthropus alongside these stone tools opens up a whole new twist in this intriguing detective story." It is therefore possible that the advanced and groundbreaking Oldowan technology was already developed by this pre-human. However: “The genus Homo was already present in East Africa at that time, even if we have not found it in Nyayanga so far. Therefore, we cannot say with certainty which hominin species these tools belonged to,” the scientists point out. In any case, the new finds prove that the Oldowan stone tools were made earlier than previously assumed and that they were even more widespread in East Africa than just in the Ethiopian Afar Triangle.
Source: Thomas Plummer (Queens College, New York) et al., Science, doi: 10.1126/science.abo7452