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Gabrielle Walker

Snowball Earth

Hay Festival 2003 , 
The science-writer explores the theory that 700 million years ago, the earth was a vast, whited-out iceball. Paul Hoffman, a brilliant and irascible Harvard scientist, claims that a climactic cataclysm 700 million years ago triggered the great Cambrian Explosion, the hitherto unexplained moment in geological time when a profusion of complex life forms first sprang from the primordial soup. Walker tells his story.