Journal of Heredity Advance Access originally published online on February 29, 2008
Journal of Heredity 2008 99(2):237; doi:10.1093/jhered/esm116
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Book Review |
Shiny Pebbles on the Beach
Darwinian Detectives, by Norman A. Johnson. Oxford University Press, NY, 2007. xviii + 220 pp, Hardback, $28.00. ISBN 978-0-19-530675-0.Although it has been almost 150 years since the "Origin of Species," we have hardly begun to understand how evolution works. This little book makes our ignorance painfully clear.
This is ironic, because the book was written as a kind of primer to bring general readers with some scientific background up to date on the latest advances in evolutionary biology. The idea is an excellent one. The book's goal is to provide people with ammunition to fight the creationist forces of ignorance, by showing that evolutionary biology is becoming just as rigorous as physics and chemistry. It does a fairly workmanlike job at this task, though for long stretches it tends to read like a textbook.
The book concentrates on the remarkable advances that have recently been made in comparative genomics and as a result of our growing ability to understand the multifarious connections between genes and phenotypes. A well-chosen selection of these stories—the apparent balancing selection that has acted on genes such as CCR5 that can be related to disease, the clear genetic distinction that can now be made between humans and Neanderthals, and the active evolutionary history of genes involved in brain size and language—are clearly presented with a minimum of jargon.
And yet there is something missing. Everyone remembers how Newton compared himself to a boy playing on the seashore, picking up an occasional shiny pebble or pretty shell "... whilst the great ocean of truth lay all undiscovered before me." The stories recounted in this book tend to be of the pretty shell variety. The larger questions remain. For example, Johnson recounts the tale of the FOXP2 gene. This gene seems to have undergone unusually rapid evolution before humans appeared (and even, as recently shown by Svante Pååbo and his colleagues, before Neanderthals appeared). FOXP2 is a regulatory gene with many talents. It plays an important role in the development of parts of the brain and of the musculoskeletal and immune systems. And it turns out to be defective in a family some of whose members show speech defects that are correlated with the presence of the defective form of the gene. But does FOXP2 really have anything to do with speech? Or do its many roles include, as the evidence is beginning to suggest, an ability to assist us in the fine motor skills necessary for speech rather than a role in speech itself? If so, then the entire ocean of undiscovered genes that really contribute to language continues to break soundlessly on the shore of our ignorance, invisible to our perceptions and at the moment quite beyond our understanding.
It would have been much more fun, and more interesting for the reader, to explore what we can infer about that ocean of ignorance. We now know that our genes are surprisingly few in number, but that their interactions are legion. The nascent science of proteomics is the study of how all these gene products interact with each other. So far it has yielded little but vast organization tables, the flow chart of a hermetic cellular bureaucracy that tells us nothing about the functioning of the bureaucracy itself. But how did all these interactions evolve, and what are the genes actually doing in these various tissues?
This and many other questions remain unexplored in this book, which instead peters out into a discussion of comparative genomics. The book will provide useful information for people who want to know what molecular evolutionists are currently doing but little about what they might do in the future to explore the vast but exceedingly alluring ocean of phenomena that lie just beyond our understanding.
Professor of Biological Sciences University of California, San Diego La Jolla, CA 92093-0116
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