A New Zealander and an Irishman quit their jobs, cash in their savings and walk 2,626 miles from Mexico to Canada along one of the longest and most challenging foot trails in the world, the Pacific Crest Trail. Their route takes them through some of the most spectacular scenery in North America, including California's deserts, alpine lakes and granite peaks of the Sierra Nevadas, and massive volcanoes and temperate rainforests of the Cascade Mountains....

In this documentary, David Attenborough examines descendants of the first mammals to develop during the dinosaur age. By eating insects, they were able to extend their territory and adapt to water and flight habitats. Shrews closely resemble their ancestors, and imitate their foraging hunting techniques. Moles have moved underground, and elephant shrews evade predators by sprinting through a well maintained trail network. Insect hunters that grew...