Everyone is familiar with Darwin's revolutionary idea about the survival of the fittest, and most people agree that it works, but Darwin's famous theory has one major chink. If life is about survival of the fittest, then why would we risk our own life to jump into a river to save a stranger? Some people argue that issues such as charity, fairness, forgiveness and cooperation are evolutionary loose ends, side issues that are of little consequence. But as Harvard's celebrated evolutionary biologist Martin Nowak explains in this ground-breaking book, cooperation is central to the four-billion-year-old puzzle of life. Cooperation is fundamental to how molecules in the primordial soup crossed the watershed that separates dead chemistry from biochemistry. Cooperation is the key to understanding why language evolved, an event that is as significant as the evolution of the first primitive organism. The book also brings to light Nowak's game-changing work on disease. Cancer is fundamentally a failure of the body's cells to cooperate but organs are cleverly designed to foster cooperation and, as Nowak explains, this new understanding can be used in novel cancer treatments. In his first book for a wide audience, this hugely influential scientist explains his cutting-edge research into the mysteries of cooperation, from the rise of multicellular life to Good Samaritans. With wit and clarity, Martin Nowak and the bestselling science writer Roger Highfield make the case that cooperation, not competition, is the defining human trait. Supercooperators will expand our understanding of evolution and human behaviour, and provoke debate for years to come.