on both sides of the base for fitting into short wooden or bone spear shafts. The largest spear point ever found, measuring nine inches long, was a Clovis point made of chalcedony, a kind of quartz.

But when it comes to bones, "the key problem is preservation". Dr Langley notes that a million years is a long time for organic objects like bones to stay intact. "If it's left on the surface ...

Some of the bones reach up to nearly 15 inches (38 centimeters) long. The bone tools, which all appear to have been systematically produced in the same style as one another, were found in Tanzania ...