IN 1662 John Graunt, a London haberdasher, published his magnum opus, Natural and Political Observations... Made upon the Bills of Mortality, and thereby established the field of epidemiology.1 Graunt brought to light a diversity of facts about human life and disease that had not previously been appreciated. He was the first to notice that the numbers of births and deaths of males exceeded those of females (by the ratio of 14 to 13); he noticed, too, that despite their greater mortality, men had less morbidity than women. Graunt quantified for the first time the high mortality in children, noting that . . .