Many ‘modern’ industrial countries have experienced major epidemics of disorders such as atherosclerotic heart disease, hypertension, diabetes, and various forms of cancer during the past few decades. Among other hypotheses, a departure from the traditional human lifestyle has been suggested as a primary factor precipitating such epidemics. After many centuries of successful human adaptation to the diet and physical demands of life as a hunter–gatherer or a low technology agriculturalist, there has been a dramatic and rapid concentration of the world's population in large conurbations where there is little possibility to sustain either a traditional diet or historic patterns of physical activity. The energy demands of city life have decreased progressively as developed countries have experienced widespread use of cars, automation of factories, mechanization of the home, and easy access to sedentary forms of entertainment such as television, video-films and computer games. A combination of store purchases and increasing affluence has shifted food consumption from traditional ‘country’ foods such as grains and vegetables to refined carbohydrates, saturated animal fat and protein. Medical advances have increased human lifespan, but at the same time advertising and other social pressures have encouraged a large fraction of ‘modern’ populations to become addicted to tobacco and other drugs.

Given the wide discrepancy between our current lifestyle and that appropriate to the evolutionary roots of our human species, adverse health consequences are hardly surprising. Unfortunately, technology was not available to document the physical condition of city-dwellers before the disturbance of their lifestyle began, and our knowledge of the effect of ‘modernization’ upon current health is correspondingly incomplete.