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.
From earthquakes to tsunamis to volcanic eruptions, natural disasters are both terrifying and fascinating - providing endless fresh material for documentary makers. But how well do disaster documentaries keep pace with the scientific theories that advance every day? To try and answer that question, Professor Danielle George is plunging into five decades of BBC archive. What she uncovers provides an extraordinary insight into one of the fastest moving branches of knowledge. From the legendary loss of Atlantis to the eruption that destroyed Pompeii, Danielle reveals how film-makers have changed their approach again and again in the light of new scientific theories. While we rarely associate Britain with major natural disaster, at the end of the programme Danielle brings us close to home, exploring programmes which suggest that 400 years ago Britain was hit by a tidal wave that killed hundreds of people, and that an even bigger tsunami could threaten us again.
Explore a corner of Namibia dominated by stifling heat and parched sand, where a desolate landscape of haunting beauty lies. While most of Etosha National Park is devoid of growth, its margins are dotted with a series of oases that attract herds of thirsty creatures: antelopes, exotic birds, and the world's biggest elephants.
Fortey is on Hawaii to investigate how life colonises a newly-born island. The most remote island group in the world, by some estimates only one new species successfully colonised Hawaii every 35,000 years - yet the Hawaiian Islands teem with a great diversity of life. In search of the evolutionary secrets of how one species becomes many, Fortey encounters beautiful honeycreeper birds whose evolution rivals that of the Darwin's famous finches; carnivorous caterpillars who now can't eat leaves; and giant silversword plants that thrive in parched volcanic soil at 10,000 feet.