Woolly mammoths were still alive when the Great Pyramid of Giza was finished. Not as bones in the ice — alive, on an island in the Arctic Ocean, at the same time as the pharaohs, the first cities of Mesopotamia and the raising of Stonehenge. They held on for another five hundred years, and then about four thousand years ago they died, all of them, and the woolly mammoth was gone. For most of the last decade the reason was settled: inbreeding. A tiny island population, genomes filling up with errors, a sick and doomed remnant limping toward an extinction