The story of life, from the first primitive cells to the plants and animals that now live around us. David Attenborough examines the uses and advantages of birds' unique possession - the feather. Man has yet to invent anything that, weight for weight, is as strong as the feather. Feathers are insulators, they provide the surface of the most perfect aerofoils known - bird's wings. Plus they play a central role in courtship.
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