According to the accepted narrative of progress, a few great humans have bent the arc of history. But in this revelatory book, Dr Jonathan Kennedy argues that germs have done more to shape humanity at every stage, from the first success of Homo sapiens over the equally intelligent Neanderthals to the fall of Rome and the rise of Islam. How did an Indonesian volcano help cause the Black Death, setting Europe on the road to capitalism? How could 168 men extract the Largest ransom in history from an opposing army of eighty thousand? And why did the Industrial Revolution lead to the birth of the modern welfare state?