Why do we blink? How did humans first stand up on two feet? And why do women menstruate when so many other mammals don't? From blurry vision to crooked teeth, it's surprising that human beings have beaten the odds as a species, the only survivors on our branch of the tree of life. Why do human mothers have such a life-endangering experience giving birth? And why are there entire medical specialties for teeth and feet? In this funny, wide-ranging book, biologist Alex Bezzerides tells us where we inherited our adaptable, achy, brilliant bodies in the process of evolution.