Human activities strongly influence a population's states of health and disease. For example, an energy-rich food supply combined with a plethora of energy saving devices, from cars to TV lounges, appears to be responsible for much of the increase in obesity which affluent societies have experienced in the past half century.
According to the World Health Organization 70 to 80% of all deaths in the industrialized world and 40 to 50% in developing countries are so-called "affluent society" diseases, attributable to high blood pressure, heart attack, stroke or lung cancer. These diseases are caused by unhealthy diet, lack of exercise and smoking.
[Developing countries] At least 600 million urban dwellers in the developing world live in what might be termed "life and health threatening" homes and neighbourhoods, and have inadequate or no access to health care. Infant mortality rates can be as much as five times higher in low income settlements than in the more prosperous middle class areas in the same city. They have the "worst of both worlds" with the traditional infection diseases plus affluent society diseases.
The World Health Organization in 1997 reported the increased incidence in developing countries of diseases usually associated with the industrialized nations: heart disease, stroke, and cancer.
In 1900, 5% of the US population died of heart disease, cancer, or diabetes. In the early-mid 1900s, heart disease and cancer were not in the top 20 causes of death in any age group.