You think you're human. But what does that mean? How can humanity be defined? Felipe Fernandez-Armesto takes us on an enlightening and provocative journey through the history of humankind to reveal the challenges to our most fundamental belief - that we are, and have always been, human. Fernandez-Armesto investigates advances in artificial intelligence and genetics, and asks what these mean for the future of human values, human rights, and the defence of human dignity. The book illustrates how our concept of humankind has changed over time and how our current understanding of this has been shaken by new challenges from science and philosophy.