Will wooly mammoths roam the tundra once more? This week we ask whether improvements in genetic technologies mean extinction is no longer the end, as well as meeting moss that came back to life after 2000 years buried in permafrost, and the million-year-old microbes lurking in the ice of Antarctica. Plus, news that our genes control who we make friends with, how fossil sea urchins hold the key to finding your lost car keys, and what ancient tooth plaque is revealing about the diets of our ancestors...