As a young man, traveling in Africa, Tim Coulson - now Professor of Zoology at the University of Oxford - became seriously ill with malaria and was told a second bout would probably kill him. Aged only 20, this brush with his own mortality led him to promise himself he would write a complete guide to science: life, the universe and everything. His aim was to understand the existence of all living things - no mean feat!

Over the course of a colourful career, Tim's work has taken him all over the world: including researching wolves in Yellowstone National Park, little fish called guppies in the rivers of Trinidad and silvereye birds on Heron Island on the Great Barrier Reef. Using complicated mathematical models he builds up a picture of ecosystems seeking to explain how predators impact both evolution and ecosystems. And finally, more than thirty years after he vowed to write the book that would explain everything we know about science, he's done just that.

In conversation with Professor Jim Al-Khalili, Tim talks about his journey from youthful ambition to science demystifier.

Presented by Jim Al-Khalili Produced by Geraldine Fitzgerald Revised for World Service by Minnie Harrop