Some of the biggest questions of our time, how to survive and adapt in a changing world, may be answered by the biggest creature of all time, the whale. Their adaptability is legendary, going from four legged land animals to the giants of the ocean.
Dr Nick Pyenson is the curator of fossil marine mammals at the Smithsonian Institution's National Museum of Natural History. He looks at some of the greatest mysteries of the whale, why they're so big, how they can dive to enormous depths with one breath. His new book is called Spying on Whales: The Past, Present, and Future of Earth's Most Awesome Creatures.