Winter is here. Ready or not, creatures big and small endure the harshest and most unforgiving season on the planet. Some cling to life in these bitter months…while others see opportunity on the ice. In this special, wildlife around the globe fights tooth and nail to survive the winter season, against a striking frozen backdrop.
The episode begins in the South American rainforest whose rich variety of life forms is used to illustrate the sheer number of different species. Since many are dependent on others for food or means of reproduction, David Attenborough argues that they couldn't all have appeared at once. He sets out to discover which came first, and the reasons for such diversity. He starts by explaining the theories of Charles Darwin and the process of natural selection, using the giant tortoises of the Galapagos Islands (where Darwin voyaged on HMS Beagle) as an example. Fossils provide evidence of the earliest life, and Attenborough travels a vertical mile into the Grand Canyon in search of them.
This programme looks at the evolution of fish. They have developed a multitude of shapes, sizes and methods of propulsion and navigation. The sea squirt, the lancelet and the lamprey are given as examples of the earliest, simplest types. Then, about 400 million years ago, the first back-boned fish appeared. The Kimberley Ranges of Western Australia are, in fact, the remnants of a coral reef and the ancient seabed. There, Attenborough discovers fossils of the earliest fish to have developed jaws. These evolved into two shapes of creature with cartilaginous skeletons: wide ones (like rays and skates) and long ones (like sharks).
The Serengeti is one of the most biologically diverse areas on earth--but it's also the scene of some of the most important fossil discoveries ever made. Join us as we meet the modern inhabitants of this ancient land, and track how their evolution helped shape our understanding of human origins.