Sharon Moalem’s central claim in Survival of the Sickest is simply stated: The traits that make us susceptible to chronic disease such as diabetes or hemochromatosis are either directly beneficial or were once so in our recent evolutionary past. On his account, insulin helped us adapt to the last ice age, and cholesterol helped us adapt to the varying intensities of sunlight at different latitudes. What’s revisionist about his claim is its sweep: Almost every non-infectious disease — and even some of these — arises from traits optimized by natural selection, and are not the result of entropy or the accidental blowback of a combination of otherwise positive traits. In short, a propensity to disease is a feature, not a bug — a feature with a manual we’re just beginning to read.
Despite Moalem’s claim to be a “maverick,” Survival of the Sickest is in fact most interesting when it remains within the bounds of mainstream knowledge. The best chapters in this book are probably the last three: on the interrelationship between people and microbes, on noncoding DNA, and on epigenetics. Although these three each take potshots at mainstream science, they also, in the main, devote themselves to explaining the fruits of well-established research — that is, how the new mainstream consensus evolved from the previous one.
On the one hand, anyone with even a passing acquaintance with epigenetics — the science that addresses how genes express traits, such that the same genetic sequence is capable of producing many variants — or the interest scientists now take in so-called “junk DNA” will recognize the book’s appeal. And the book’s central rhetorical trick — playing around freely with “why” and “what if” — is certainly engaging, as it moves from the necessarily technical scientific papers to an imaginative reconstruction of evolutionary history.
On the other hand, as the book’s subtitle suggests, Survival of the Sickest can be facile, almost to the point of irresponsibility. Outside of the fantasies of House, identifying yourself as a “medical maverick” is usually a signal of quackery, and Survival of the Sickest frequently risks devolving into nonsense. Moalem frequently invokes the specter of such scientists as Barbara McClintock, whose research into transposition and genetic regulation was overlooked or worse for many years until genetic research caught up with her. (She ended up a Nobel Laureate in 1983.) From these figures, he argues that science is pointlessly conservative, and often laments, for example, “the chilling effect conventional wisdom can have on the scientific community”. It’s hardly shocking anymore to argue that scientific paradigms both enable and tend to prevent certain kinds of discoveries — I mean, The Structure of Scientific Revolutions is more than 40 years old. The wisdom of Carl Sagan’s famous maxim, that “extraordinary claims require extraordinary proof” is lost on Moalem, who appears to argue from the idea that tantalizing claims are themselves their own proof. He doesn’t quite call fellow researchers “haters,” but he does come close.
The revolutionary stance has some problems, though. Any time Moalem can cite a “prominent journal” (such as Nature Genetics), he is happy to do so, but of course journals can only become prominent through the withering — and thus potentially “chilling” — effect of peer review. As a result, the evidence in Survival of the Sickest can seem a bit cherry-picked: Science is good when its prestigious results support my speculations, but it’s conformist and plodding when it points out that certain speculations run counter to lots and lots of observable data. A deeper problem is that Moalem sometimes seems to believe that the simple fact of a theory’s being rejected or marginal means that there must be some truth to it. For example, he devotes a significant section of his final chapter to presenting the infamous Aquatic Ape Hypothesis, which suggests that humans share important traits with aquatic mammals rather than, or in addition to, those we share with primates. After citing a vague and somewhat handwaving summation of the theory, Moalem notes that “it starts to sound an awful like common sense”. I have a hard time thinking of a genuine scientific discovery that is commonsensical. (Evolution, the age of the earth, the fact that the apparently stable earth is spinning, the movement of the earth around the sun, black holes … none of these bear the remotest resemblance to “common sense.”) Moalem even launches a slightly quixotic defense of Lamarck, positioning him as an epigeneticist before his time but also arguing, in a slightly incoherent way, that Lamarck really didn’t formulate a theory of the inheritance of acquired traits. He even coyly describes Lysenkoism as “an extreme twist on acquired characteristics” and as a “fascinating period in history”. Frankly, it was a downright shock when Moalem dismisses the cryopreservationist firm Alcor as practitioners of junk science.
Survival of the Sickest manages to be both breezy and exhausting. The book is a very fast read, and Moalem does an excellent job teasing out the practical implications of technical scientific debates. But Moalem’s jokey demeanor wears thin quickly. By the time I’d read the interplay of life and the environment referred to as “a global, evolutionary Macarena”, I was ready to dropkick the book — and that was still in the preface! Evolution and disease is a fascinating topic; for now, however, Randolph Nesse and George Williams’s Why We Get Sick is a better introduction.