Books, Naturally
Evolution for Everyone: How Darwin's Theory Can Change the Way We Think About Our Lives
David Sloan Wilson. 2007. Delacorte Press, New York. 390 pp., hardbound. $24.
Of the fewer than half of adult Americans who accept the fact that we evolved from an earlier species, most don't give the matter much more thought. That our ancestors and our closest living relatives are hairy apes, cool as that might be, doesn't help us get through another dreadful day at the office. But evolution is about lots more than the ancient branches of our family tree, as the renowned evolutionary biologist Theodosius Dobzhansky wrote in a 1973 essay called, "Nothing in Biology Makes Sense Except in the Light of Evolution."
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In Evolution for Everyone, Binghamton University evolutionist David Sloan Wilson focuses that light on human biology to illuminate how thinking as an evolutionist will lead to a better understanding not only of our bodies but our behavior and even the basis of morality. In essence, Wilson argues that the only way to make sense of human and all life—to answer the why questions—is in the framework of evolutionary theory. Moreover, this understanding can be profoundly useful for forging a better life. And anyone—everyone!—can do it because the theory of evolution by natural selection is conceptually so simple.
Sloan likens it to a recipe with three ingredients. Start with variation among individuals in any attribute or behavior. Add the survival and reproductive consequences—the costs and benefits—of that variation: being smaller or braver or whatever leads to longer lifespan and more babies than being bigger or fearful in a particular environment. Then throw in "a sort of yeast that makes the recipe come to life" —heredity (the fact that children tend to be like their parents)—and, over time, the smaller or braver individuals will predominate due to their superior adaptations to the environment.
Following the recipe, it's easy to conjure up hypotheses about why animals, including humans, are what they are and do what they do. (Although it's usually not easy to test them—Wilson does a great job describing the "roll-up-your-sleeves" work that scientists must to do to document facts "the way a brick factory produces bricks." In addition to reading this book for his witty, clear elucidation of evolution theory, read it for the insight Wilson offers into how scientists work and think, and, through detailing his personal experiences, how they navigate through the contemporary academic habitat.)
Take just one example of the many Wilson offers to support the utility of evolutionary thinking to human well-being. Infanticide is not uncommon in the animal world and on the surface looks like a bad idea. Thinking like an evolutionist, however, makes this seemingly aberrant behavior explicable.
Under what conditions might infanticide be advantageous, defined as increasing the killer's reproductive success, and thus evolve? Lack of resources, food for instance, might favor eliminating some of your own offspring so the others survive. Further, if some of those offspring are of poorer quality than others (smaller, weaker, say), then it would be advantageous to eliminate those rather than their bigger, stronger siblings.
Another situation that favors the evolution of infanticide is when the offspring aren't your own. It may benefit a male, for instance, to kill the young of another male if doing so makes room for his own. Wilson's own experiments with infanticidal burying beetles clearly support two of these three hypotheses and, he suspects, will support the third when he does the tests. Indeed, the infanticidal behavior in many species, including lions and langurs, is explained by one or all of these three hypotheses.
And what of our own species? One team of scientists has combed homicide records and other data sources to find that scarce resources and offspring quality explain variation in the occurrence of infanticide in both modern and traditional human cultures, too. Further, and most surprising, a human infant is 20 to 100 times more likely to be killed by a stepparent than a natural parent! Evolutionary thinking identified genetic relatedness as an important risk factor for infanticide and its lesser form, child abuse, a factor not previously considered by criminologists and social scientists. Knowing this is the first essential step toward minimizing these crimes.
Among the many other subjects that Wilson's evolutionist thinking sheds new light on are why we get sick, the current obesity crisis, why we dance and enjoy music, and even why we are religious, which Wilson repeatedly points out is not at odds with our being evolutionists. Wilson also weaves into his story a host of examples from the animal world, reminding us that the differences between human and other animals are products of evolution as well.
Evolution for Everyone is as fascinating as it is readable. This is the rare work of scientific writing that all can peruse for pleasure and intellectual profit. You could even take it to the beach.
—Susan Lumpkin
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ZooGoer 36(4) 2007. Copyright 2007 Friends of the National Zoo.
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