These tools were made a very, very long time ago. Over 10,000 years ago, in what we now call the Stone Age. And to show how long ago that is, I'm going to walk back in time. This is today.

They took a hands-on approach, and crafted replicas of tools that might have been used in the Early Upper Paleolithic age (about 38,000–30,000 years ago). The findings are published in the ...