This week we trace an incredible human journey. Why did our ancestors leave the warm cradle of humanity in Africa and spread across the world? We are probably all descendants of a very small but fearless bunch of people. Doctor and archaeologist Alice Roberts takes up the story in an exclusive preview of her forthcoming documentary on BBC2 The Incredible Human Journey.

Swine flu and how worried you should really be about it. We give you our no-nonsense, hype-free guide.

We also hang out with some butterflies at the Natural History Museum and investigate why these beautiful creatures are slowly disappearing.

All that plus a gene for autism, a status report on the health of the planet and some risqué pictures in space.

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