As one of North America's leading science writers, Carl Zimmer brings excellent qualifications to this book. His earlier work, "Evolution: Triumph of an Idea" skilfully explained the history of life. His "Parasite Rex", despite the topic, is a delightful read. In this book, focused on how the human branch of life's historical tree grew and developed, he again weaves his careful research and fine writing into a highly understandable survey. With a collection of vivid illustrations to enhance the text, this work poses a difficult selection choice for those interested in what we know of our origins.
The title is evocative, but the book's brevity and the dynamics of the science of palaeoanthropology necessarily limit what can be presented. Zimmer doesn't spend overmuch time in dealing with the history of the science. Instead, he deals with the topics involved in how fossil finds and genetics research provide clues to how humanity developed over the millennia. With the paucity of available fossils and the indeterminate nature of historical genetics, absolute answers on human evolution are sparse. New finds in both fields challenge any thesis, provide endorsement or refutation in equal measure. Zimmer is fully up to handling these vagaries, carefully guiding us through the questions, the evidence and the resolution. He's quick to point out where questions, even new ones generated by recent research, remain to be addressed. One could almost believe him to be a field researcher, when he laments the need for new exploration and evidence brought up for study. He also keeps pace with the emergence of innovative techniques providing the analytical tools that point to answers.
The eight chapters comprising the body of the book explain how random the finding of fossils truly is. Sahelanthropus tchadensis was revealed in a wind-blown Sahara basin, while the earliest Homo erectus was taken from a jungle river ravine. Stone tools may erode from a stream channel or appear in sediments that once fringed an ancient lake. Dating, that fundamental aspect that places the various finds in respect to one another, is also an indeterminate. Volcanoes, spewing ash-bearing crystals, is the major form of calendar to the field worker. The calendar must be set for place as well as time, since our ancestors had the capacity to emigrate. Zimmer explains how their wandering from continent to continent has both clarified and confused the picture we have of the tree. Was every branch from a single trunk, or did many trunks form, spouting new species in various locations?
Our wanderings result from one of the great mysteries of human evolution. Unlike any other mammal, we are wholly bipedal. Why should that capacity have evolved, and did it change our lifestyle, or was our behaviour a result of standing upright? Zimmer poses these questions and the scholars who have offered answers. Hominid fossils, always fragile, rarely provide clear explanations. Leg length compared to arm's reach is but a guideline. Jaws, rib cages and other elements must be carefully detailed, the author notes. Even when things seem clarified, a new factor may intrude to force revision of ideas.
The two major factors that brought about human uniqueness are, of course, tool making and language. While other animals, even birds, can apply tools and certainly have methods of communication, it is left to our lineage to develop these elements in highly complex ways. We alone, Zimmer reminds us, developed talents for planning how a tool should look to perform its task properly. Language, no matter how it started or developed across the world, granted us the ability to pass ideas down the generations. Skills learned were exchanged, and the growth of a brain stimulated by hunting and group living was further stimulated. Modern genetics, Zimmer explains, has revealed genes, particularly FOXP2, which promote language learning. Forms of FOXP2 exist in other species, although its role for them remains unclear. Language, however, is also instrumental in our spread over the planet. Ironically, it may have been the "competitive edge" our species had that allowed it to eliminate our closest cousins, the Neanderthal.
Like all books on human origins, this one suffers from "calendaritis" - new research has nudged some of Zimmer's effort to one side. That in no way reduces the value of this book. What is more questionable is the small physical size and large margins. That reduces the font and deprives the author of room to expand on topics needing the space. While the graphics are excellent for the size of the book, they may have been given more prominence than necessary. The publisher, as so often happens with books of this type, disrupts the flow of the text with "sidebar boxes". These are always useful, and usually necessary, but improper placement can be disruptive. Entire pages given over to skull images are of doubtful value, although the comparative arrangements greatly enhance the narrative. It's a hard choice, giving this book four stars, but five won't truly reflect its worth. If you must make a choice in selecting the prime survey on human origins, "The Complete World of Human Evolution" by Chris Stringer and Peter Andrews remains your best bet. Until a new set of fossils is found! [stephen a. haines - Ottawa, Canada]
