Early human relatives may have used tools to butcher hippos and other large game almost three million years ago. This is suggested by finds of animal bones and carved stones in south-west Kenya. Experts around Rick Potts from the National Museum of Natural History in Washington date the objects in the journal "Science" to an age of around 2.9 million years.
The find is one of the oldest stone tools ever. The objects belong to the so-called Oldowan. This is how the archaeological culture with the world's oldest stone tools is described. They go back as far as three million years. The find is one of the oldest, if not the oldest example of Oldowan technology, according to a statement from the museum. The findings indicated that the culture was more widespread than previously thought even in its early phase. However, it is not finally clear who exactly used the tools.
At the site, the researchers also dug up two molars from Paranthropus pre-humans - a branch of the primate branch that ultimately led to Homo sapiens. But did these distant cousins also make and use the tools?
"For a long time, researchers assumed that only the genus Homo -- to which humans belong -- was able to make stone tools," says Potts. The discovery of the Paranthropus teeth near the tools raises the question of who worked on them. Several groups of prehumans may have been able to make these types of tools.
Tracy Kivell, director at the Max Planck Institute in Leipzig and not involved in the study, sees the finds as further evidence that the manufacture of stone tools was not limited to homo species. However, this is difficult to prove. She assumes that the tools found were mainly used for plants because relatively few cutting marks were found on the hippopotamus bones.
The tools represent a kind of set of different devices, consisting among other things of a hammer or impact stone and a cutting stone. "These tools are better at crushing things than an elephant's molar - and they're better at cutting than a lion's canine," says Potts. With the new technology, these pre-humans would have had a greater food supply on the African savannah.
East Africa has been a "boiling cauldron of environmental change," with cloudbursts and droughts, says Potts. The food supply was constantly changing. “The Oldowan devices could have cut and crushed everything. By doing so, they helped early toolmakers adapt to new places and opportunities, whether it was a dead hippopotamus or a starchy root,” says Potts.
At the site called Nyayanga, the researchers found, among other things, incomplete remains of hippos whose bones show signs of cuts. Antelope bones have also been found, providing evidence that meat was scraped off and bones were crushed to get at bone marrow.
The team also examined the wear patterns on the tools. These were probably used for scraping as well as for cutting and hammering. Since early humans were only able to deal with fire much later, the food was eaten raw. The meat may have been processed into a kind of raw hippopotamus mince to make it easier to swallow.
The team emphasizes that somewhat older tools were found at another site in Kenya. But these are much more roughly worked. Oldowan tools were the dominant implements until about 1.7 million years ago. Specimens have been found in northern Africa and along the east coast of the continent, among other places.
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