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.

While early human ancestors started making stone tools at least 2.6 million years ago, bone tools took much longer to appear. The earliest signs of a regular use of bone tools hadn’t shown up in the archaeological record until around 500,

The development of tool technology is considered a pivotal step in human evolution. Deliberately shaped stones are thought to have emerged in cultures more ancient than our own genus Homo to strip more marrow and meat from kills, which in turn may have played a key role in our own evolutionary success.