Death is life's greatest certainty. But that may be about to change. Scientists have discovered an immortal animal that may hold the secret of endless regeneration. They're on the brink of editing our DNA so that we can cure death like a disease. Or is dying necessary for the survival of our species?
Dame Sally Davies talks to Brian Cox about her interest in antibiotic resistance and admiration of Alexander Fleming and Howard Florey for their development of penicillin.