A remarkable discovery was made a decade ago on a dig in northern Kenya. When all the bone and skull fragments were painstakingly pieced together, they revealed the nearly complete skeleton of a teenage male (nicknamed Nariokotome boy, after a nearby sand river). Faced with the best-ever specimen of Homo erectus - a species long identified as the proverbial missing link between apes and humans - paleoanthropologist Alan Walker embarked on a long-term investigation of that species's nature.

In this book, telling the story of that inquiry, he introduces us to his ever surprising, deeply engrossing world.

Walker examines even the tiniest of bones and the subtlest of clues in his analysis. He first recounts the story of the more-than-century-long search for the "missing link," a bizarre and compelling saga made up of brilliant science and speculative nonsense. Then he builds, step-by-step, on some of his predecessors' assumptions, and he challenges others, using state-of-the-art techniques to reveal the truth.

In Walker's hands the bones reveal an amazing amount of information about the Nariokotome boy's anatomy and the way he lived. We watch as Walker deduces from the evidence that community and cooperation were already very important at this stage of human evolution; that the boy was modern in climatic adaptation and locomotion yet archaic in growth pattern; and that the boy could not speak. In Walker's final assessment this last insight becomes the most important one.