Linguists can reconstruct long-dead languages that no one ever wrote down. These reconstructions can be surprisingly precise: individual words, grammar, sound changes, even something of the world the speakers inhabited.

The method: compare what the descendant languages still share and work backwards from there.

The biggest success story of this comparative method is the reconstruction of Proto-Indo-European, likely spoken around six thousand years ago on the grasslands north of the Black Sea.

Its descendants include English, Hindi, Greek, Russian, Welsh, and many hundreds more. And our reconstruction of their common ancestor is detailed enough to tell us what its speakers ate and drank, how they buried their dead, and even the names of some of their gods.