Filmed over two years in a remote part of the Canada. Cameras observe a young female grizzly as she grows into adulthood. Filmed over two years, the documentary features vistas of open plains on the Arctic Circle and frigid rivers in vast mountain ranges. Against the backdrop of the vast Yukon tundra, the climate changes from frigid winter to spring thaw with a brief sunny season in-between. The cast of characters features hulking male grizzlies, mothers and cubs socialising until the salmon runs begin. Female bears must consume enough salmon during this brief time in order to sustain the cubs that will be born during the winter.
The next programme deals with flying insects. It begins in Central Europe, where the Körös River plays host to millions of giant mayflies as they rise from their larval skins to mate. — the climax of their lives. Mayflies and dragonflies were among the first to take to the air about 320 million years ago, and fossils reveal that some were similar in size to a seagull. Damselflies are also looked at in detail.
The next instalment describes the move from water to land. The fish that did so may have been forced to because of drought, or chose to in search of food. Either way, they eventually evolved into amphibians. Such creatures needed two things: limbs for mobility and lungs to breathe. The coelacanth is shown as a fish with bony fins that could have developed into legs, and the lungfish is able to absorb gaseous oxygen. However, evidence of an animal that possessed both is presented in the 450 million-year-old fossilised remains of a fish called a eusthenopteron. Three groups of amphibians are explored.
Cameras follow Japanese macaques in the snow-covered mountains of Japan, as they gather at steaming hot thermal pools to bathe and socialise. Elsewhere in the cool mountains of Mexico, cameras capture a spectacular gathering of billions of monarch butterflies, and in Bavaria, Germany, Spy Beaver gains unique access to the secretive world of the beaver.
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.
In the second episode, Iain discovers how flowers have transformed our planet. He journeys to the remote islands of the South Pacific to track down the earliest flowers. In the deserts of Africa and rainforests of Vietnam, he sees how they brought brilliant colour to the most barren landscapes and sculpted the earth itself. And he learns how they drove the evolution of all animals - kick-starting our human story.