Ben Garrod, primatologist and master skeleton builder, shares his unique passion for bones. He embarks on a very personal journey through the remarkable and surprising story of how a single, universal body plan - the skeleton - has shaped the animal kingdom. There are over 62,000 species of vertebrate of every size and shape from squirrels to sperm whales and aardvarks to anacondas. Each skeleton differs in small, but critical ways and, in Ben's hands, those differences are decoded to reveal an animal’s complete life story - not only how it moves, where it lives and what it eats, but also its entire evolutionary journey. Secrets of Bones brings the remarkable world of bones to life in a unique way. By conducting fascinating experiments, meeting expert contributors, using integrated graphics and a wealth of archive from the BBC's Natural History Unit, Ben unlocks a fascinating and hidden world we never get to see. In this episode, Evolutionary biologist and master skeleton builder Ben Garrod discovers how the skeleton has adapted for vertebrates to move on land in a remarkable number of ways. They can swing through the trees, slide on the forest floor, dig through dark subterranean worlds and run at speed across the savannahs. Ben explores the role of the spine in both cheetahs and snakes, shows how adaptations to the pentadactyl limb have helped gibbons and horses thrive and how one unique bone in the animal kingdom has been puzzling scientists for years.