homo sapiens

This is a recent and, in the long view, abnormal condition. For almost the whole of the human story, the Earth held several kinds of human at once. As recently as fifty thousand years ago — a flicker, in the time-scales this project works in — our planet was home to Homo sapiens in Africa and the Near East, the Neanderthals across Europe and western Asia, the Denisovans somewhere in the vast Asian interior, the tiny Homo floresiensis on an Indonesian island, and another small human, Homo luzonensis, on a Philippine one.

We left the previous entry at a gate. Our species had existed for something like a quarter of a million years, almost all of it inside Africa. It had pressed against the northern exits more than once, during the wet intervals when the desert greened, and each time it had fallen back, leaving no lasting line beyond the continent. Then, sometime around seventy thousand years ago, the corridors opened again, and this time the people who passed through kept going. Everything in this entry follows from that crossing.

But before anyone could enter the empty hemisphere, they had to survive the cold that guarded its door. That is where the story begins.