Book excerpt: How and when did we become the only human species to settle the whole earth? How did our brains become so large? In this book, Clive Gamble sets out to answer these fundamental questions, digging deep into the archives of archaeology, fossil ancestors and human genetics. The wealth of detail in these sources allows him to write a completely new account of our earliest beginnings: a deep history in which we devised solutions not only to the technical challenges of global settlement but also cracked the problem, long before writing and smartphones, of how to live apart yet stay in touch.