Around 13,000 years ago, the Earth burned. A swarm of comet debris from the Taurid meteor stream had blasted the Americas and parts of Europe; the worst day in prehistory since the end of the ice age. Many species of large animal were exterminated by the conflagration and ensuing cataclysms. And those that survived the initial onslaught could do little against the floods, acid rain, and starvation that followed.