Oliver Sacks travels once again in search of human diversity...Always fascinated by islands, Oliver Sacks is drawn to the Pacific by reports of the tiny atoll of Pingelap, with its isolated community of islanders born totally colour-blind; and to Guam, where he investigates a puzzling paralysis endemic there for a century. Along the way, he re-encounters the beautiful, primitive island cycad trees – and these become the starting point for a meditation on time and evolution, disease and adaptation, and islands both real and metaphorical.