Two-million-year-old molecular fossils reveal flourishing woodlands and widespread animals in Greenland's pre-Ice-Age past, and give hints to the Arctic’s future under global warming. We hear from a molecular palaeontologist and a climate modeller. DNA also reveals the enduring genetic influence of our extinct Denisovan cousins on disease immunity in modern Island Southeast Asians. And the art and science of 3D-printing violins If your home is drafty, filling in holes and cracks can help tackle rising energy bills, and lower your carbon footprint. But is there a limit to how airtight we should make our homes? That’s what CrowdScience listeners Jeff and Angie wondered when weatherproofing their doors and sealing up cracks for the winter. Once every last gap is blocked, will enough air get in for them to breathe properly? How would they know if they’ve gone too far? With Covid-19 making us more aware than ever of the importance of good ventilation, CrowdScience investigates how to make your home cosy and energy-efficient without sacrificing fresh air in the process. And we find out how, in hotter climates, you can carefully tap into your drafts, to reduce energy-intensive air conditioning. With contributions from Kimble Smith, Professor Nicola Carslaw, Dr Iain Walker, Marion Baeli and Dr Yashkumar Shukla. (Image credit: Beth Zaiken/bethzaiken.com)