Using whole genome sequencing and cutting-edge analyses researchers at Stockholm University have uncovered the surprising evolutionary history of the Norwegian lemming (Lemmus lemmus), revealing it to be one of the most recently evolved mammal species. The results published in Proceedings of the National Academy of Sciences (PNAS), reveal that the Norwegian lemming is a distinct species that split from its closest relative, the Western Siberian lemming, approximately 35,000 years ago — just before the peak of the last Ice Age.