In the second episode, "Your Inner Reptile," Shubin exposes our reptilian roots. He searches for our ancient ancestors at fossil sites in the Karoo Desert of South Africa and on the tidal flats of Nova Scotia. He also reveals modern-day links to the past through visits to a fertility clinic in Chicago and a biology lab in London. Along the way, he explains how major transitions in the history of life paved the way for our ancestors' evolution into mammals. Shubin identifies some amazing connections: the amniotic sac was an innovation to keep our reptile ancestors' eggs from drying out; our complex teeth can be traced to ferocious beasts that lived millions of years before dinosaurs; and our hair is linked to the whiskers of reptile-like mammals that lived much of their lives in the dark. Our reptilian ancestors — from fearsome predators to creatures as small as a paper clip — are responsible for more than a few features of modern humans.