We know more about our bodies than ever before, but why are there so unanswered questions? Why do our elbows and knees bend in opposite directions? Why do men and women walk differently? Why do men have nipples? Why is childbirth so painful? Why do we sleepwalk? Why do so many of us suffer from back pain and dental problems? This book sets out to answer these questions and many others as it traces our evolution, not from apes, but from our more distant ancestors - the fish. Accessible and endlessly fascinating, Your Body reveals which features we have inherited from our fish, amphibian, reptile, four-legged mammal and primate ancestors and explores how the human body is likely to evolve in the future.