A long term study of diversity between two ethnic groups was developed in Evans County, Georgia. The findings are predicated on the genotypic-phenotypic interactions, with the multitude of environmental factors. The genetic-environmental interaction ultimately determines the individual's state of health or disease. For example, coronary heart disease prevalence and incidence rates were extremely low for blacks in Africa and four times lower than whites in rural South Georgia in the 1960s. Excessive hypertension and diabetes mellitus, and greater cerebrovascular disease mortality in black men, is now well known. Blood pressure levels studied in rural Africa were normal and did not rise with age, whereas blacks, conversely, demonstrated twice as much hypertension in South Georgia as whites and demonstrated an inverse relation between education and blood pressure (ie, the lower the education the higher the blood pressure). Cultural adaptation has accelerated hypertensive disease and strokes in blacks, while there remains an excess of atherosclerotic coronary heart disease in white men. Secular trends suggest that coronary heart disease is decreasing among white men but may be increasing in black men. Studies of ethnicity and biracial populations provide important cardiovascular disease associations with clinical risk factor studies.