Archaeologists recently identified a site with stone tools thought to be 2.8 million years old, according to a new study published in Science. The researchers say the stone tools were used to butcher hippos in what is currently western Kenya. The tools were also used for processing plants and bone marrow. 

“With these tools, you can crush better than an elephant’s molar can and cut better than a lion’s canine can,” said Rick Potts, National Museum of Natural History Peter Buck Chair of Human Origins and the study’s senior author. “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.”

The Oldowan tools recently found in Africa are some of the oldest stone tools ever discovered. Researchers identified three different types of them: Hammerstones were used to hit other rocks when making tools. Oval-shaped cores were used to split or flake objects when struck with a hammerstone. Flakes could also aid in cutting and scraping. Archaeologists consider all three types of tools as sophisticated for their time period. For comparison, hand axes are thought to have been invented some 1.7 million years ago. 

The dig site where the tools were found also contains the bones of butchered animals, including hippo and antelope remains with bones showing scars of flesh being flaked away and marrow extracted by the crush of hammerstones. Somewhat surprisingly, scientists also found two molars belonging to Paranthropus, a primitive and distinct early relative of homo sapiens. The early hominins ate their food raw. According to Smithsonian Magazine, early humans likely did not start using fire until around 800,000 years ago.

“East Africa wasn’t a stable cradle for our species’ ancestors,” Potts said. “It was more of a boiling cauldron of environmental change with downpours and droughts and a diverse, ever-changing menu of foods. Oldowan stone tools could have cut and pounded through it all [and] helped early toolmakers adapt to new places and new opportunities, whether it was a dead hippo or a starchy root.”

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“This is one of the oldest, if not the oldest, examples of Oldowan technology,” said Thomas Plummer, Smithsonian Human Origins Program research associate and study lead author. “This shows the toolkit was more widely distributed at an earlier date than people realized and that it was used to process a wide variety of plant and animal tissues.”