Rapid health changes in the U.S. and other industrialized nations of the world during the twentieth century are being roughly paralleled in the developing nations, some decades later. These changes include the reduction of communicable diseases, a striking decrease in infant mortality and lower death rates through the age-span, and the emergence and decline of the “modern” epidemics such as coronary heart disease. Increase in life expectancy at birth and at age 65 is one immediate and already measurable impact of these trends. Making several assumptions about the future health of mankind, such as no devastating virus disease epidemics and no further nuclear warfare, one can project three consequences of the health trends described: (1) an almost vertical age-structure of the population, rather than the previous and present pyramidal shape; (2) greater social and individual attention to maintaining health, beyond combatting major diseases; and (3) gradual dissolution of the barriers to association among the peoples of the world.