Humans evolved a robust inflammatory response to fight constant threats like infections. In today's relatively sterile world, this powerful system lacks its historical targets and can overreact to modern triggers, leading to the chronic low-level inflammation that is at the heart of many modern diseases.

Beyond climate impact, 70% of antibiotics are fed to farm animals, fostering superbugs that threaten modern medicine. Industrial farms also act as incubators for zoonotic diseases, posing catastrophic risks to global health and the economy.

Our ancestors were healthy by default because their environment promoted it. Today, the default environment—filled with processed foods, sedentary lifestyles, and novel chemicals—systematically produces unhealthy people, making good health an uphill battle of individual effort against the system.

Genetic data shows natural selection on immune and metabolic traits intensified dramatically 5,000 to 2,000 years ago. This suggests that high-density living and close contact with animals during the Bronze Age created a more powerful evolutionary pressure than the initial shift to farming.

All populations that developed agriculture descend from ancestors who lived long before its invention, implying the necessary cognitive abilities were in place. The simultaneous, independent emergence of farming worldwide points to a global environmental trigger: the unprecedented climate stability of the last 12,000 years (the Holocene).

Studies of traditional populations show their microbiomes are vastly different from those in industrialized nations. This suggests that what is considered a 'healthy' American microbiome might actually be a perturbed state, silently predisposing individuals to chronic inflammatory and metabolic diseases due to factors like antibiotics and diet.

For millennia, human innovation like agriculture and shelter was driven by stress reduction. This endeavor was so successful that it created the modern "comfort crisis." We have eliminated natural stressors so effectively that we must now artificially re-engineer challenges like exercise back into our lives to maintain physiological health.

The agricultural industry's singular focus on yield has created an inverse relationship where crop output rises while nutritional density declines. This incentive structure is a root cause of poor public health outcomes linked to modern diets.

The TYK2 gene variant, a risk factor for tuberculosis, increased in frequency for thousands of years before plummeting in the last 3,000. This suggests it protected against an earlier threat but became a liability with the rise of endemic tuberculosis in denser populations, showing how selection can reverse direction.