Survival of the Sickest: A Medical Maverick Discovers Why We Need Disease by Sharon Moalem, Jonathan Prince

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This fascinating book was prompted by one nagging question: Why hasn't evolution rooted out all the debilitating hereditary diseases that still plague us? Neurogenetics specialist Dr. Sharon Moalem thinks that he knows the answer. According to him, diabetes, hemochromatosis, cystic fibrosis, and sickle cell anemia exist because each offers evolutionary advantages to offset its negative consequences. He asserts, for instance, that diabetes might be the byproduct of a mechanism that helped humans survive the Ice Age. Survival of the Sickest also helps explains why African Americans living in northern climes might suffer from vitamin D deficiencies and why Asians have a lower tolerance for alcohol than Europeans.

From the Publisher

Was diabetes evolution's response to the last Ice Age? Did a deadly genetic disease help our ancestors survive the bubonic plagues of Europe? Will a visit to the tanning salon help lower your cholesterol? Why do we age? Why are some people immune to HIV? Can your genes be turned on -- or off?

Joining the ranks of modern myth busters, Dr. Sharon Moalem turns our current understanding of illness on its head and challenges us to fundamentally change the way we think about our bodies, our health, and our relationship to just about every other living thing on earth, from plants and animals to insects and bacteria.

Through a fresh and engaging examination of our evolutionary history, Dr. Moalem reveals how many of the conditions that are diseases today actually gave our ancestors a leg up in the survival sweepstakes. When the option is a long life with a disease or a short one without it, evolution opts for disease almost every time.

Everything from the climate our ancestors lived in to the crops they planted and ate to their beverage of choice can be seen in our genetic inheritance. But Survival of the Sickest doesn't stop there. It goes on to demonstrate just how little modern medicine really understands about human health, and offers a new way of thinking that can help all of us live longer, healthier lives.

Survival of the Sickest is filled with fascinating insights and cutting-edge research, presented in a way that is both accessible and utterly absorbing. This is a book about the interconnectedness of all life on earth -- and, especially, what that means for us.

Publishers Weekly

Moalem, a medical student with a Ph.D. in neurogenetics, asks a number of provocative questions, such as why debilitating hereditary diseases persist in humans and why we suffer from the consequences of aging. His approach to these questions is solidly rooted in evolutionary theory, and he capably demonstrates that each disease confers a selective advantage to individuals who carry either one or two alleles for inherited diseases. But very little is new; the principles, if not every particular, that Moalem addresses have been covered in Randolph Nesse and George Williams's Why We Get Sick, among others. Whether he is discussing hemochromatosis (a disorder that causes massive amounts of iron to accumulate in individuals), diabetes or sickle cell anemia, his conclusion is always the same: each condition offers enough positive evolutionary advantages to offset the negative consequences, and this message is repeated over and over. Additionally, Moalem's endless puns and simple jokes wear thin, but his light style makes for easy reading for readers new to this subject. (Feb.) Copyright 2006 Reed Business Information.

Tina Neville Copyright 2007 Reed Business Information - Library Journal

History does not always receive a great deal of attention in the scientific disciplines, yet this book shows us exactly why it shouldn't be ignored, even in the more analytical areas of genetics and medicine. Moalem (Ph.D., neurogenetics & evolutionary medicine) uses numerous examples to show how analyzing history might help explain why a certain genetic trait that seems useless—even harmful—to us now made perfect sense in our ancestors' environment. He also introduces such recent research topics as host manipulation, noncoding DNA, and epigenetics. The particularly coherent writing style makes complex ideas accessible to people without a science background. With the book's emphasis on evolution's goals of survival and reproduction, readers will gain insights into why evolution may have selected for certain traits and why having that insight may better our lives. Highly recommended for general audiences. [See Prepub Alert, LJ6/15/06.]

Kirkus Reviews

Certain disease-related genes may make you sick but protect you from a worse fate-death-argues unconventional medical researcher Moalem. Currently completing his training at Mount Sinai School of Medicine (he already has a Ph.D. in neurogenetics and evolutionary medicine), the author includes many examples to support his contention that "one man's disease is another man's cure." People with a genetic tendency for sickle-cell anemia, for example, have better natural resistance to malaria. Moalem provides evidence that a hereditary condition called hemochromatosis, which causes iron to build up in the body, may have arisen to protect people from plague and that vulnerability to diabetes may have been an adaptation to ice ages. The accumulation of sugar in blood made more concentrated by frequent urination lowers the freezing point so people don't freeze to death, he asserts. Dark-skinned people moving to northern climates may be more susceptible to heart disease because they carry genes for the excess cholesterol they needed in areas of intense sunlight. Other sections describe how plants and animals co-evolve as they adapt to climate changes and how a parasite like the Guinea worm "manipulates its victims to collaborate in the infection of others." We should use such knowledge to develop new strategies to defeat parasites rather than relying on drugs, Moalem suggests. He sees hope for ways to combat cancer that involve turning on or off selected genes-indeed, he has much to say about the dynamism of the human genome. The final chapters report research suggesting that environmental events in early pregnancy may have far-reaching effects on offspring. The author also takes seriously ElaineMorgan's idea that human evolution may have involved an aquatic phase. Moalem's lively and enthusiastic treatise offers enough plausible explanations for interesting phenomena that you'll be willing to forgive its more outre speculations. Agent: Tracy Fisher/William Morris Agency

Product Details

• ISBN: 0641889844
  
• ISBN-13: 9780641889844
• Format: Hardcover, 288pp
• Publisher: HarperCollins Publishers
• Pub. Date: February 2007
• Edition Description: Bargain
• Sales Rank: 1,916

• Read an Excerpt

Read an Excerpt

Ironing it Out

Aran Gordon is a born competitor. He's a top financial executive, a competitive swimmer since he was six years old, and a natural long-distance runner. A little more than a dozen years after he ran his first marathon in 1984 he set his sights on the Mount Everest of marathons—the Marathon des Sables, a 150-mile race across the Sahara Desert, all brutal heat and endless sand that test endurance runners like nothing else.

As he began to train he experienced something he'd never really had to deal with before—physical difficulty. He was tired all the time. His joints hurt. His heart seemed to skip a funny beat. He told his running partner he wasn't sure he could go on with training, with running at all. And he went to the doctor.

Actually, he went to doctors. Doctor after doctor—they couldn't account for his symptoms, or they drew the wrong conclusion. When his illness left him depressed, they told him it was stress and recommended he talk to a therapist. When blood tests revealed a liver problem, they told him he was drinking too much. Finally, after three years, his doctors uncovered the real problem. New tests revealed massive amounts of iron in his blood and liver—off-the-charts amounts of iron.

Aran Gordon was rusting to death.

Hemochromatosis is a hereditary disease that disrupts the way the body metabolizes iron. Normally, when your body detects that it has sufficient iron in the blood, it reduces the amount of iron absorbed by your intestines from the food you eat. So even if you stuffed yourself with iron supplements you wouldn't load up with excess iron. Once your body is satisfied with the amount of iron it has, the excess will pass through you instead of being absorbed. But in a person who has hemochromatosis, the body always thinks that it doesn't have enough iron and continues to absorb iron unabated. This iron loading has deadly consequences over time. The excess iron is deposited throughout the body, ultimately damaging the joints, the major organs, and overall body chemistry. Unchecked, hemochromatosis can lead to liver failure, heart failure, diabetes, arthritis, infertility, psychiatric disorders, and even cancer. Unchecked, hemochromatosis will lead to death.

For more than 125 years after Armand Trousseau first described it in 1865, hemochromatosis was thought to be extremely rare. Then, in 1996, the primary gene that causes the condition was isolated for the first time. Since then, we've discovered that the gene for hemochromatosis is the most common genetic variant in people of Western European descent. If your ancestors are Western European, the odds are about one in three, or one in four, that you carry at least one copy of the hemochromatosis gene. Yet only one in two hundred people of Western European ancestry actually have hemochromatosis disease with all of its assorted symptoms. In genetics parlance, the degree that a given gene manifests itself in an individual is called penetrance. If a single gene means everyone who carries it will have dimples, that gene has very high or complete penetrance. On the other hand, a gene that requires a host of other circumstances to really manifest, like the gene for hemochromatosis, is considered to have low penetrance.

Aran Gordon had hemochromatosis. His body had been accumulating iron for more than thirty years. If it were untreated, doctors told him, it would kill him in another five. Fortunately for Aran, one of the oldest medical therapies known to man would soon enter his life and help him manage his iron-loading problem. But to get there, we have to go back.

Why would a disease so deadly be bred into our genetic code? You see, hemochromatosis isn't an infectious disease like malaria, related to bad habits like lung cancer caused by smoking, or a viral invader like smallpox. Hemochromatosis is inherited—and the gene for it is very common in certain populations. In evolutionary terms, that means we asked for it.

Remember how natural selection works. If a given genetic trait makes you stronger—especially if it makes you stronger before you have children—then you're more likely to survive, reproduce, and pass that trait on. If a given trait makes you weaker, you're less likely to survive, reproduce, and pass that trait on. Over time, species "select" those traits that make them stronger and eliminate those traits that make them weaker.

So why is a natural-born killer like hemochromatosis swimming in our gene pool? To answer that, we have to examine the relationship between life—not just human life, but pretty much all life—and iron. But before we do, think about this—why would you take a drug that is guaranteed to kill you in forty years? One reason, right? It's the only thing that will stop you from dying tomorrow.

Just about every form of life has a thing for iron. Humans need iron for nearly every function of our metabolism. Iron carries oxygen from our lungs through the bloodstream and releases it in the body where it's needed. Iron is built into the enzymes that do most of the chemical heavy lifting in our bodies, where it helps us to detoxify poisons and to convert sugars into energy. Iron-poor diets and other iron deficiencies are the most common cause of anemia, a lack of red blood cells that can cause fatigue, shortness of breath, and even heart failure. (As many as 20 percent of menstruating women may have iron-related anemia because their monthly blood loss produces an iron deficiency. That may be the case in as much as half of all pregnant women as well—they're not menstruating, but the passenger they're carrying is hungry for iron too!) Without enough iron our immune system functions poorly, the skin gets pale, and people can feel confused, dizzy, cold, and extremely fatigued.

Iron even explains why some areas of the world's ocean are crystal clear blue and almost devoid of life, while others are bright green . . .