This instalment examines the earliest land vegetation and insects. The first plants, being devoid of stems, mainly comprised mosses and liverworts. Using both sexual and asexual methods of reproduction, they proliferated. Descended from segmented sea creatures, millipedes were among the first to take advantage of such a habitat and were quickly followed by other species. Without water to carry eggs, bodily contact between the sexes was now necessary. This was problematical for some hunters, such as spiders and scorpions, who developed courtship rituals to ensure that the female didn't eat the male.
Remote islands offer sanctuary for some of the planet's strangest and rarest creatures. The rare pygmy three-toed sloth enjoys a peaceful existence on an idyllic Caribbean island, while nesting albatross thrive in predator-free isolation. But island life always comes at a cost. On the Galapagos Islands, young marine iguana must escape an onslaught of deadly racer snakes the moment they hatch from the sand. On the sub-Antarctic island of Zavodovski, life gets more extreme still. Every day, one and a half million penguins risk being battered against the rocks by fierce waves as they try to get on and off the island.
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).
Sharks are more than just hunters. Only now are discoveries revealing a hidden side to their character. They have an intricate social life, complex courtship rituals, surprising ways of bringing up their young and extraordinary powers of navigation. They can forge relationships with the strangest of partners, even humans.
David Attenborough takes a breathtaking journey through the vast and diverse continent of Africa as it has never been seen before. (Part 5: Sahara) Northern Africa is home to the greatest desert on Earth, the Sahara. On the fringes, huge zebras battle over dwindling resources and naked mole rats avoid the heat by living a bizarre underground existence. Within the desert, where the sand dunes 'sing', camels seek out water with the help of their herders and tiny swallows navigate across thousands of square miles to find a solitary oasis. This is a story of an apocalypse and how, when nature is overrun, some are forced to flee, some endure, but a few seize the opportunity to establish a new order.
This is the story of two young animals forced to grow up fast. In Africa's savannah, a baby elephant shrew learns how speed is the secret to survival amongst the largest animals on Earth; and in America, a young grasshopper mouse confronts the Wild West's deadliest creatures to stake a claim of his own.