"A science journalist tours a suite of characteristics, both anatomical and behavioral, that typify human beings.... Two of them his readers can consult directly: the big toe and the thumb. His discussion covers their functions, considered against the evolutionary advantages they might have conferred on the African savanna. In that vein, Walter presents paleoanthropology and famous fossils such as Lucy. He also directs attention to the applicability of genetics and neurobiology to unique human qualities, especially brain size. Its increase through the series of hominid species guides Walter's exploration of the ramifications of humans' large brain, such as self-awareness, language, and emotion. For those who wonder if talking and crying have evolutionary origins and survival benefits, Walter points to scientists active in researching such questions. A fluid introduction to the development of the human species."—Booklist