A cache of 1.5 million-year-old bone tools uncovered in Tanzania suggest ancient human ancestors were capable of critical thinking and advanced craftsmanship.

These were not just random tools made opportunistically, but show a consistent manufacturing process that must have been culturally transmitted.

Our ancestors were making tools out of bones 1.5 million years ago, winding back the clock for this important moment in human evolution by more than a million years, a study said Wednesday. And more than two million years ago,