Animal life on earth began 500 million years ago. But how did the species diverge, and what role does the inner support of the spine play in this? The famous natural scientist David Attenborough presents new findings in evolutionary research, which precisely dates fossils, analyses them with virtuosity and brings them to life in a fascinating way with computer animation. Part 1 traces the evolution of fish, which conquer the land as reptiles and from there swing into the skies.