Six million years of biological evolution have produced a human body ill-adapted to the diets and lifestyles that cultural evolution has wrought since modern humans emerged. That is the core message of this massive review of where we came from and what ails us now.
Lieberman (Human Evolutionary Biology/Harvard Univ.; The Evolution of the Human Head, 2011, etc.) writes authoritatively about the fossil record, crediting bipedalism as the driver that freed hands to learn new skills, enabled foraging for diverse diets and chasing prey, and ultimately built bigger brains. In time, humans spread across the globe in hunter-gatherer groups. Thus we remained until the agricultural and industrial revolutions spurred population growth, changed diets, and introduced new infectious and chronic diseases—while little altering our hunter-gatherer anatomy and physiology. Lieberman examines energy balance—calories taken in vs. calories expended—and good shape. Analyzing today’s creature comforts, processed food (with addictive amounts of sugar, salt and fat) and lack of exercise, it is no wonder we are seeing rises in obesity and risks for heart disease, diabetes, osteoporosis and the like. Lieberman calls these diseases of “mismatch” (of biological evolution and culture) and medicine’s emphasis on treating symptoms, “dysevolution,” which means perpetuating the diseases instead of preventing them. The repeated emphasis on all the bad things humans do is wearying. By no means does Lieberman discount all the good that modern society has achieved, but that message is nearly drowned by the constant admonition to do right by your body. Alas, he is the first to admit that changing human behavior is notoriously hard. At best, he offers a “soft paternalism”—e.g., government controls of children’s environments (more physical education and better lunches) and taxing the unhealthy choices of adults.
Readers have likely heard this song before but perhaps not so exhaustively and well-referenced as in Lieberman’s opus. Would that industry and governments take heed.