We aren't the only species that communicates, makes tools, or has sex for reasons other than procreation, but we have developed a culture far more complex than any other we've observed. Why has that happened, and what does it say about us? Here the author of A Brief History of Everyone Who Ever Lived finds that many things once deemed exclusively human are not—like raptors who start fires to scatter prey, for example, or a chimp who started a "fashion" of wearing grass in one ear. Published in Britain as The Book of Humans, Adam Rutherford's evolutionary history is a synthesis of genetics, sex, and migration that reveals what unequivocally defines us as animals, as well as what makes us unique.