Why We Get Sick: The New Science of Darwinian Medicine

Why We Get Sick dismantles the conventional view of disease as mere mechanical breakdown. Instead, it proposes a revolutionary framework: Darwinian medicine. This paradigm argues that to truly understand illness—from cancer and heart disease to allergies and anxiety—we must ask not just how the body fails, but why natural selection, a process that shapes organisms for survival and reproduction, left us vulnerable to such failures in the first place. It shifts the inquiry from proximate biology to ultimate evolutionary causation.

The book systematically explores the core principles of this new science. It explains that many symptoms we treat as problems, such as fever, vomiting, and pain, are actually evolved defenses. These defenses represent the body's sophisticated, if sometimes crude, solutions to threats like infection or injury. The authors delve into the concept of evolutionary trade-offs, illustrating how traits beneficial for reproduction in our ancestral environment can predispose us to disease today, as seen in the trade-off between bipedal locomotion and back pain. A central theme is the relentless co-evolutionary arms race with pathogens, which explains the persistence of infectious diseases and the inevitability of antibiotic resistance.

Further chapters examine the critical idea of mismatch: our Stone Age bodies are ill-equipped for the modern world of abundant calories, sedentary habits, and environmental toxins, leading to epidemics of obesity, diabetes, and autoimmune disorders. The analysis extends to aging and genetic diseases, framed not as programming errors but as consequences of selection's diminishing power after reproductive age and the persistence of harmful genes that may have offered other advantages.

Ultimately, Why We Get Sick is a foundational text that recontextualizes all of human pathology. Its significance lies in offering clinicians, researchers, and intellectually curious readers a powerful new lens for diagnosis, treatment, and prevention. It argues that by understanding the evolutionary 'why' of sickness, we can develop more profound, effective, and compassionate medical strategies, moving beyond symptom suppression to address the deeper roots of human suffering.

The consensus hails the book as a seminal, paradigm-shifting work that fundamentally alters how one thinks about health and disease. Readers praise its intellectual rigor and the profound clarity it brings to puzzling medical phenomena. The primary critique is that the prose can feel dry and academic, more a series of compelling scientific arguments than a fluid narrative, which some find challenging despite the fascinating subject matter. It is widely regarded as essential but demanding reading.