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.)