Have you ever wondered why our bodies look the way they do? Paleobiologist Neil Shubin sets out in this three-part series to find the answers in a surprising place: the ancient animal ancestors that shaped our anatomy.
In the first episode, "Your Inner Fish," he journeys back to a time, some 375 million years ago, when the first fish crawled up onto land. Shubin's quest for the fossil record of this primeval predecessor takes viewers from highway cuts in rural Pennsylvania to the remote Arctic. After years of searching, he and his colleagues finally found a fossilized fish, known as Tiktaalik, that had enough strength in its front fins to do pushups and heave itself out of the water. Remarkably, we can trace the ancestry of our own hands and arms all the way back to these fins. Viewers also meet the scientists who discovered the DNA recipe for constructing the human hand — an essential set of instructions passed down from fish like Tiktaalik and shared today with a surprising number of other animals, from chickens to chimpanzees. Along the way, Shubin makes it clear that we can also thank our fishy past for many of our body's quirks, such as hernias. We are, every one of us, just a jury-rigged fish.
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.
In the final episode of the series, "Your Inner Monkey," Shubin delves into our primate past. He travels from the badlands of Ethiopia, where the famous hominid skeletons "Lucy" and "Ardi" were found, to a forest canopy in Florida, home to modern primates. En route, he explains how many aspects of our form and function evolved. We learn that a genetic mutation in our primate ancestors conferred humans' ability to see in color — but it was an advantage that led to a decline in our sense of smell. The shape of our hands came from tree-dwelling ancestors for whom long fingers made it easier to reach fruit at the tips of fine branches. Shubin concludes by tracing the evolution of the human brain — from a tiny swelling on the nerve cord of a wormlike creature, to the three-part architecture of a shark's brain and the complex brain of primates. As Shubin observes, "Inside every organ, gene and cell in our body lie deep connections with the rest of life on our planet."