On Start the Week Andrew Marr looks at winners and losers - from microbes and genes, to athletes and adventurers. Ed Yong seeks to expand our understanding of microscopic microbes which inhabit every corner of the earth, and influence our bodies more than we know. Each person's DNA is unique but Adam Rutherford reveals how collectively it tells the story of the history of our species - the successes and the failures. When one's own genetic make-up and hard work aren't enough, there's always chemical enhancement - Jonathan Maitland looks at doping in sport for his latest play, Deny, Deny, Deny. The polar scientist Felicity Aston was the world's first woman to ski alone across the Antarctic and knows what it's like to push your body to the limits. She's now off to Canada's frozen North in search of gold. Producer: Katy Hickman.