"Masters of the Planet" provides an excellent overview of the current state of our knowledge of the evolution of humans and other hominids. Back in the 1960s, hominid evolution could still be viewed as unilinear and progressive, leading towards "Homo sapiens " along a single axis of evolutionary change. As outlined in this book, an impressive array of fossil finds and sophisticated technical analyses have yielded a very different picture, one in which diverse lineages of hominids existed simultaneously and interacted. The profusion of paleontological discoveries has buried the traditional creationist myth of "missing links." Indeed, the sheer number of fossils and structurally intermediate forms has sometimes made it difficult to determine which of the many candidates is closely- related to which.
Ian Tattersall, author of "Masters of the Planet", is curator emeritus at the American Museum of Natural History in New York. He brings to the issues a lifetime of expertise in hominid evolution, as well as abundant experience in writing books and articles for fellow scientists and general audiences. The book is organized historically, and traces the diverse and complicated history of hominids over the past 7-8 million years. Beginning with the ancient origins of the hominid lineage, it outlines the rise of bipedal apes, the variety of australopiths (including "Lucy"), life on the savannah, emergence from Africa (an event that occurred multiple times), the spread of early "Homo" throughout the Old World continents, the enigmatic Neandertals (distant cousins to ourselves, not ancestors - except to the degree in which we interbred), and ultimately, the arrival of modern "H. sapiens. " The book does not focus entirely on skeletal features. Rather, such aspects as development of social behavior, running ability, loss of body hair, diet, use of fire, and cooking all get their due. Tattersall's account leads towards recognition of the distinctiveness of our species, as manifested by language as well as symbolic behavior, features that he considers to be responsible for our species' success.
In tracing hominid diversity and evolutionary history, Tattersall draws on contemporary technological analyses to reveal details that would have been unimaginable a decade or so ago. Thus, readers may be surprised to find what isotope analyses have revealed about diets of early hominids, and what genetic analyses have shown about skin and hair color in Neandertals. Tattersall does not shy from recognizing unresolved issues and persistent controversies. He fairly presents alternative viewpoints, and freely acknowledges areas where a scarcity of evidence has rendered divergent interpretations viable.
As one who has read many books on hominid evolution, I found Tattersall's work to be interesting and informative. My copy is now replete with penciled comments and bent- down page corners to mark fascinating issues and controversial matters. While the book's dealings with uniqueness of our own species' overlaps that of Brian Fagan's recent "Cro-Magnon," I found Tattersall's account preferable in some respects. The latter recognizes the emergence of artistic expression (starting at least 70,000 years ago) as a worldwide phenomenon rather than one local to Europe and Asia, in accord with its status as a species characteristic.
Notwithstanding my high regard for this book, it is not free of error. The hyoid apparatus is not a "bony portion of the Adam's apple" (as stated on page 36). Rather, the hyoid consists of thin cartilages that support the tongue and its musculature, while the so-called Adam's apple is the larynx. (How the two could be confused by a paleo-anatomist is most puzzling). "Exaptation" is wrongly presented as a non- adaptationist mechanism (pages 44, 68, and 210), in which features arise by chance and only later evolve to take on a function. Evolutionary biologists will recognize this characterization as mistaken. In exaptation, features that are evolutionary adapted to serve one function are transformed through natural selection to serve some new function (as outlined in Gould and Vrba's original 1982 paper in Paleobiology and throughout the modern literature). As another example, the author suggests that "members of the genus "Homo" have been consistently predisposed in the same way towards brain size increase"(page 132) since brain enlargement occurred in three separate lineages. However, one need not infer any special mechanism or attribute unique to our genus. A trend towards brain enlargement has occurred independently in many mammalian lineages, as well as in numerous linages of birds and cartilaginous fishes, and even among molluscs and arthropods. In this respect, hominids appear (with aquatic mammals) as an extreme example of a widespread evolutionary trend.
Some interpretations in the book are quite speculative, leading to weak inferences. For example, discovery of one toothless male skull (the Dmanisi specimen) is taken as evidence for long- term compassionate behavior among "Homo erectus" era hominids, on the grounds that the individual would not have been able to chew his own food. (Page 124: "...it seems entirely reasonable to conclude that the Dmanisi hominids had the cognitive reserves to express their fellow- feeling in the form of material support"). In view of the profusion of other interpretations, the inference is unnecessarily speculative. One might also question the book's central claim that emergence of artistic expression in our species paralleled the development of a unique form of psychology, as manifested in our capacity for symbolic thought. Fossils reveal little about psychology, and how early symbolic thought arose arguably is entirely a matter of speculation - cave art and jewelry notwithstanding.
Such issues do not detract from a work that, on the whole, is one of the best modern accounts available; indeed, some of the above manifests the fascinating and thought - provoking nature of this book. Overall, I would strongly recommend "Masters of the Planet" as an interesting and informative account of the diversity and evolutionary history of the bipedal apes and we their descendants.