Three million years ago, camels roamed through Greenland’s endless forests and our ancestors lived in the trees. It all came to an end with the Ice Ages. What died and what survived, as natural selection shaped the evolutionary tree during this epochal shift from hot to cold? Until now, scientists have known less about the natural world before the Ice Age than they did about the age of dinosaurs, which ended 64 million years ago. A new discovery is set to reveal this lost world, species by species. Led by Danish gene-hunter Eske Willerslev, a team of scientists for the first time in history is sequencing DNA from before the Ice Age. The picture that emerges is of a hot planet, when forests blanketed the Arctic and carbon levels matched those in our atmosphere today. Is this a portrait of our own climate future?