The inside of a termite mound proved especially challenging for Attenborough: it was so cramped that he could only face in one direction. He therefore had to slowly crawl backwards out of shot when performing re-takes.
Every year, thousands of salmon make their way upstream along the nearly 2000-mile-long mighty Yukon River, desperate to reach spawning beds. Eagerly checking their progress is a host of hungry predators, from grizzly bears to bald eagles-all desperate to stock up on protein before the long winter months ahead.
The Miller-Urey experiment was the first attempt to scientifically explore ideas about the origin of life. Stanley Miller simulated conditions thought be common on the ancient Earth. The purpose was to test the idea that the complex molecules of life (in this case, amino acids) could have arisen on our young planet through simple, natural chemical reactions.
The next programme explores the various sea-living invertebrates. In Morocco, the limestones are 600 million years old, and contain many invertebrate fossils. They fall broadly into three categories: shells, crinoids and segmented shells. The evolution of shelled creatures is demonstrated with the flatworm, which eventually changed its body shape when burrowing became a necessity for either food or safety. It then evolved shielded tentacles and the casings eventually enveloped the entire body: these creatures are the brachiopods. The most successful shelled animals are the molluscs, of which there are some 80,000 different species.
Once a rich wilderness teeming with lions, tigers and cheetahs, the Gangetic plains of northern India have been transformed into the most densely populated place on Earth. The film explores the impact of this tide of humanity on the wildlife of the plains - from the all-out war between elephants and villagers to worship of the deadly cobra.
Takes us into the world of digestion and its amazingly complex environment.Our health, body shape, mood and even our evolution are determined by the unseen life forms that swarm throughout our bodies. There are worms in your bowels, bacteria in your mouth, fungi in your lungs and even viruses in your DNA.The combined genetic information of all these bugs is more than 150 times greater than our own genes. Their cells outnumber our own by 10 to 1. This collective menagerie is called the microbiome, and in a very real sense, it is the making of us all.