As the saying goes: “extinction is forever.” The list of extinct animals, like Steller’s sea cow, the Tasmanian wolf and the dodo, is depressing. And despite various efforts, extinction seems final.
But when does extinction start? That would seem like an easy question to answer. In the dry prose of the International Union for Conservation of Nature (IUCN), extinction has occurred when “there is no reasonable doubt that the last individual of a species has died.”
