But 31,000 years ago, the ice was already extensive and the climate was already cold.

The situation was not yet at its worst, but it was severe.

The northern hemisphere was dramatically different.

The British Isles were connected to continental Europe by a broad plain of dry land.

The North Sea did not exist.

The Baltic was a frozen lake.

The northeastern Siberia where the Yana site sits was not covered by glacial ice — the northeast Asian and Beringian regions were largely ice-free even during the glacial maximum, which is part of why they could support human populations — but the climate was genuinely Arctic in character, with temperatures averaging well below zero for most of the year.

The key ecological concept for understanding this world is the Mammoth Steppe.