AbstractSurvival curves for men and women dying from cardiovascular disease and similar curves for those dying from cancer in 47 countries were compared with the 1970–1974 per capita incomes of the inhabitants. The data were taken chiefly from 1964 life tables. The steepest survival curves were found in countries with the highest incomes. Comparison of the survival curves in different countries and comparison of cardiovascular survival with cancer survival curves indicate that both groups of diseases are probably diseases of senescence.The differences in survival slopes are interpreted as homeostatic responses in the population to rate of food intake. The response protects the population against long-term effects of changes in food supply by promoting differential reproduction of offspring best suited to the food supply rate from the environment. The response to food supply rate complicates calculation of the effects of protracted exposure to low-level ionizing radiation because the radiation exposure appears to mimic the effect of extra food.