In the first episode Dr Alice Roberts looks at how our skeleton reveals our incredible evolutionary journey.
Trekking through the forests of our ancient ancestors, she goes to meet the apes who still live there today - chimpanzees. In six million years we have become very different, and what kick-started this can be found in an extraordinary fossil - Sahelanthropus. A single hole where the spine was attached suggests that our ancestors started the journey to being human by standing upright. We take it for granted, but standing up and walking is surprisingly complex - each step involves the co-ordination of over 200 muscles.