Penetrating up to a mile underground while lugging as much paraphernalia as an Everest assault team, the author and his team discover the oldest life on the planet - organisms that could provide the key to life on earth and that will undoubtedly deepen our ecological understanding. Taylor names these organisms 'dark life', and reports that they 'form complex ecosystems and food chains wholly independent of sunlight, photosynthesis, oxygen and other standard requirements for "life as we know it"'.