It is estimated that 99 per cent of species have become extinct, and there have been times when life's hold on earth has been so precarious it has seemed to hang on by a thread.

This documentary focuses on the survivors, the old-timers whose biographies stretch back millions of years, and who show how it is possible to survive a mass extinction event which wipes out nearly all of their neighbours. The Natural History Museum's Professor Richard Fortey discovers what allows the very few to carry on going - perhaps not forever, but certainly far beyond the life expectancy of normal species. What makes a survivor when all around drop like flies?