Reports of the National Center for Science Education

Review: Darwinian Detectives

Darwinian Detectives: Revealing the Natural History of Genes and Genomes
Norman A Johnson
New York: Oxford University Press, 2007. 220 pages.
Reviewed by
Rebecca L Cann

Just about every topic under the banner "why genetics is important to understand and still amazing to many professional biologists" is covered in this compact book. What a delight to read about some well-chosen examples, glittering in succinct detail and presented in a manner designed to intrigue and captivate a general audience. After all, where else can you find the forensic details about how a dentist did in an ex-lover with an HIV infection, what the chimpanzee genome project could tell us about differences between the sex lives of all three chimpanzees, the true origins of Akita dogs, or what red-haired singers might have in common with talking Neanderthals? Think of the conversation starters at your next sushi bar encounter, where you can captivate an audience with details about the genomes of smooth versus spiny pufferfish! Then toss off a few comments about the delta 32 mutation in CCR5 and the Black Plague, followed by the link between silaic acids and huge brains, and you are sure to be voted geek of the week. The amazing thing is that Norman Johnson has been able to show the scientific method making sense of the world in all this crazy detail.

A designed biota would not be as messy, as haphazardly assembled, or as truly jerryrigged as the genetic systems cobbled together in the last billion years of random processes and presented here for your total wonderment.

Johnson starts with the general, boxing the math for readers to skip over completely or come back to later, and moves to the specific in well-organized sections. The book starts with a good exposition of the methods scientists use to deduce how genomes are organized and how they got that way, that is, evolution. His discussion on natural selection, both positive and negative, is clear and easy to follow. The focus on how scientists are able to identify cases of positive selection sets the stage for discussions of how populations (simple and complex, marine and terrestrial) have changed over time. In cases where morphological shifts cannot be clearly linked to environments undergoing directional change, he also does a good job of introducing a reader to the idea of balancing selection. If you had an hour to read a chapter a week, covering this book would be like taking a good college biology seminar in a semester with your favorite teacher. You come away with enough background to critically dissect a too facile news story, like the one for a "language gene" or "killer male gene". And if your interest runs to recreational genetics as in ancestry testing, you will learn enough here to know that even a $1000 test fee is going to give you a probability statement, not an identity link.

There is one glaring error on page 160 in the text, easily corrected, but unfortunate because it concerns dogs and how they changed in their domestication from a wolflike ancestor. Dogs have been bred to diverse body shapes, colors, and personalities, so much so that behavioral geneticists are particularly keen to unlock many secrets about genes contributing to behavioral patterns using the dog genome as a model system. Because many people have close relationships with their pets and may have missed early stages of behavioral development with their own children, this topic is close to a reader's heart and important to get right. So, when Johnson talks about the latest information from large-scale nuclear gene testing of 85 breeds of dogs and suggests that dogs originated from African stock, contradicting previous mitochondrial DNA work, he does so because he misidentifies the basal breeds in the dog tree as African, when in fact they are Asian. Anthropologists can now note that I am finally arguing for an Asian ancestry of one species dear to humans.

Another minor quibble is his failure to include a good discussion of superbugs, or bacteria resistant to multiple antibiotics. Hospital acquired infections are important in an aging population undergoing more intense medical care, and while the latest statistics can be scary for someone spending time in an intensive care unit, it is also clear that school gymnasium facilities and hotel rooms with dirty remote controls or bedspreads can also be a problem. Herd immunity assumed by parents in an attempt to avoid autism risks, where failure to vaccinate has contributed to measles epidemics nationwide, is also a public health issue far more immediate than a potential bird flu mutation, yet these topics do not appear. Instead, a final chapter on genome evolution that attempts to give the big picture falls flat, and suffers from both over- and undersimplification, especially in the discussion of transposable elements and gene regulation.

I hope that biology teachers nationwide looking for evidence of evolution to engage their students with take a look at this book. I also hope that physicians who have a shaky understanding of evolutionary processes feel inclined to refresh how their practices can contribute to or detract from the general health of their patients. This slim volume sparked many discussions with airplane seatmates, and clearly covers stories that will resonate with a variety of readers. If a paperback version appears, it would also be a good text for a non-majors biology or an advanced placement high school class. Armed with the right information, these folks may themselves become citizen scientists.

This version might differ slightly from the print publication.

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