Scientist looks at how civilization affects health

While modern medicine has defeated some diseases, N.C. State biologist says our alienation from nature has created new problems

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• Nonfiction

  The Wild Life of Our Bodies: Predators, Parasites, and Partners That Shape Who We Are Today

  Rob Dunn

  Harper, 304 pages.

Modern medicine and improved public health practices have dramatically increased Americans' life expectancy in the past 100 years. Disease after disease has been cured or tamed. Surprisingly, though, some illnesses - autism, lupus and diabetes, for example - are becoming more common. As N.C. State University biology professor and author Rob Dunn, puts it, we "are getting sick in new ways."

Dunn thinks civilization has fundamentally changed our relationship with nature. We are more removed from it, and "we are sicker, less happy, and more anxiety-ridden for it." Behaviors that were once sensible no longer are. Our insatiable craving for sweets and salty foods made sense millennia ago when sugar and salt were hard to come by. Because they were scarce, no appetite governor evolved to tell us when to stop eating them. So, today, when sugar and salt are readily available and cheap, many of us overdo it, putting ourselves at risk for hypertension and diabetes.

Dunn is a born storyteller. His good nature, humor and creative approach to science shine through on every page. His chapter on the appendix, for instance, starts with a riveting story about a man in a submarine who develops appendicitis. It's World War II, the sub cannot get to port, and no doctor is on board. Using kitchen utensils, a sailor with little medical experience performs a tabletop appendectomy. The operation was successful; both the patient and the very nervous amateur surgeon survived.

Dunn uses this incident as a lead-in to a long-standing question: Why do we have an appendix anyway? The answer: No one knows for sure. It may be a vestigial organ with no useful purpose. A more recent theory holds that the appendix acts as a reservoir for useful bacteria.

In tale after well-told tale, Dunn recounts similar stories involving men, women, bacteria, worms and lice. However, it is not always obvious how some of the stories advance the author's central idea about the effects of civilization on human health.

Dunn postulates, for instance, that a fear of snakes is a characteristic we inherited from our ancestors, for whom snakes were a common and deadly menace. Maybe we even developed improved vision to spot them, as one scientist claims. But exactly how snake stories, interesting as they are, fit the author's thesis is unclear. It seems unlikely that "we are sicker, less happy, more anxiety-ridden" because of our separation from snakes.

On balance, though, the book's insights far outweigh its weaknesses. It is a good read with much to teach us. Many of Dunn's tossed-off asides are especially delightful. In one passage, he proposes a modification to the widely held theory known as biophilia.

Although Dunn never mentions his name, the chief proponent of biophilia is the dean of American biologists, the famous Harvard professor E.O. Wilson. In his book, "The Diversity of Life," Wilson defines biophilia as "the connections that human beings subconsciously seek with the rest of life." That statement is too broad for Dunn. Tigers and parasites, he writes, are living things, but we do not seek a connection with them. Nor do we need more contact with rats and roaches.

In Dunn's view, what we do need is a connection not with "the rest of life," but with those species that benefit us. He ends his mini-essay by redefining biophilia in a way that could serve as the theme for this book: "(W)hat we need," he concludes, "are more of some aspects of nature, its richness and variety and, more pointedly, its benefits."

Phillip Manning's most recent book is "Quantum Theory." His book reviews and essays on science are available at www.scibooks.org.