What brings about the extinction of a species? Is it a genetic flaw or a run of really bad luck? All scientists agree on the fact of extinction, but science has never agreed on its physical causes. From the traditional theory of climatic change to the controversial theory of meteorites, this book investigates each possibility and puts the arguments for and against. Questioning much of the conventional wisdom, this book makes a number of claims, including a theory that blames all significant extinctions on falling meteorites.