Today’s elephants are the ragged threads of what was once a greater blanket of proboscidean diversity. The mammoths, mastodons, and dwarfed island elephants of just a few thousand years ago are all gone, leaving only the African bush elephant, African forest elephant, and Asian elephant. But prehistory’s pachyderms didn’t slip away in lock step. It is not as if all archaic elephants everywhere keeled over at the exact same moment, ushering out the Pleistocene and marking the start of our present Holocene era.

Many of the lost elephants disappeared by about 10,000 years ago, while some of the isolated island mammoths persisted until about 4,000 years ago, spanning the gap between wild prehistory and the modern world. A group of Chinese