This episode details the origins of the vertebrates, which lie in the primitive fish that once swam in ancient seas. Remarkable advances allowed them to make the radical move onto land, and then take to the skies with the advent of flight. Brand new discoveries of fossils - ancient and living - combined with stunning CGI enable David to chart their unexpected journey out of the water to populate all corners of the globe.

David Attenborough embarks on an epic 500-million-year journey to unravel the incredible rise of the vertebrates. The evolution of animals with backbones is one of the greatest stories in natural history. To tell this story, David presents explosive new fossil evidence from China, a region he has long dreamt of exploring and the frontier of modern paleontological research. He reveals how vertebrates came to be the dominant form of animal life, and why humans are the heirs to a magnificent evolutionary heritage. This episode reveals how mammals developed from tiny nocturnal forest dwellers to the dominant form of life on the planet following the death of the dinosaurs. David explains how the meteoric rise of mammals led to an astounding diversity of life and laid the foundations for the ascent of man.