SURVIVAL OF THE SICKEST

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 Elaine Morgan’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 outré speculations.