The genetic book of the dead A Darwinian reverie

Studying animals' adaptations and genetic makeup reveals insights about the historical environments they evolved in, according to this astute study. Evolutionary biologist Dawkins (Flights of Fancy) suggests that the geometrid stick caterpillar looks like "a detailed description of ancient twigs" and that the stout potoo bird, whose brown plumage resembles tree bark, is "a perfect model of long-forgotten stumps." This kind of analysis can be applied to more ambitious reconstructions of evolutionary history, Dawkins contends. For instance, he describes how scientists deduced that an ancient turtle species had likely lived on land before returning to the water from the fact that the reptiles had bodily dimensions that more closely resembled modern tortoises than sea turtles, but developed armored breastplates before back shells, indicating that their predators usually struck from below and were thus aquatic. Dawkins also notes that humans have vestigial, unexpressed genes that, if activated, would greatly enhance the species' olfactory senses. The author's talent for rendering complex concepts in lucid prose remains intact, though he spends much of the latter half of the book rehashing arguments he made in The Selfish Gene about how genes "cause (in a statistical sense) their own survival" by conferring advantages to the bodies they inhabit. Though this covers some familiar ground, it's still worth checking out. Illus. (Sept.)

The famous evolutionist meditates on his favorite topic. Dawkins, bestselling author ofThe Selfish Gene,The God Delusion, and numerous other landmark books, argues persuasively that every living creature's body and behavior can be read as a book. Confronted with a hitherto unknown animal, a future biologist could decipher its entire evolutionary history. Today's scientists lack the technology and fossil record to deliver a detailed account, but few are more qualified than Dawkins to make the effort. Demonstrating more good sense than many of his colleagues, he makes generous use of photographs and Lenzová's expert illustrations. The author emphasizes that every individual's genes came to be the way they are over many generations through random drift and mutation guided by natural selection. Sexual recombination ensures that the gene pool is stirred and shaken, while mutation sees to it that new variants enter the pool. Natural and sexual selection determine the shape of the average genome changes in constructive directions. Individuals, species, and the physical DNA die, but the information in the DNA can last indefinitely. Having laid the groundwork, Dawkins proceeds with several dozen mind-bogglingly fascinating anecdotes describing animals, often wildly disparate, dipping into the ancient history of their DNA to solve problems in similar ways. A mole is a mammal, and a mole cricket is a bug. Adapted to life underground, they have evolved to look nearly identical. The same applies to marsupial and modern placental mammals, who have evolved separately for more than 150 million years. The cuckoo learns nothing from its parents, whom it never encounters, yet its DNA provides everything it needs to know from the species' long history, including its song and its eggs, the design of which invariably changes to resemble eggs in the nest it parasitizes. Ingenious stories in the service of deep natural history. Copyright (c) Kirkus Reviews, used with permission.