David visits archaeological sites where fossils were found illustrating the origins of life on earth, in the ocean. For long, evolution worked very slow and species remained primitive, mostly single-cell, alter fractal. Only the invention of sexual reproduction kick-started genetic diversification.
David Attenborough travels to the Canadian Rockies where fossils document an explosion in animal diversity. Going on to Africa, Australia and Scotland, Attenborough discovers how animals evolved to conquer not only the oceans but also the land and air.