Reconstruction of the skull of a Homo naledi infant

Brett Eloff Photography/Wits University

This is an excerpt from Our Human Story, our newsletter about the revolution in archaeology. Sign up to receive it in your inbox for free every month.

The word “fossil” is one I type most often. You’ll often read stories about new hominin remains described as fossils. But wait. Fossils take a long time to form, so how old does a human bone or tooth need to be before it counts as a fossil? Should…