Known. Early people shaped tools from the bones of hippos and elephants.
In Olduvai Gorge, in northern Tanzania, 27 bone tools are about 1.5 million years old. The largest were made from elephant bone. Smaller ones were made from hippo bone. The bones were fresh, and people chipped them in the same way they chipped stone. Some tools are nearly 38 centimetres long.
The page says no one knows which kind of early human made the tools, or exactly what work they did.