English statistician, one of the first demographers, and by profession a haberdasher.
Graunt, along with his friend William Petty, developed early human statistical and census methods that later provided a framework for modern demography. He is credited with producing the first life table, giving probabilities of survival to each age. Graunt is also considered as one of the first experts in epidemiology, since his famous book was concerned mostly with public health statistics.
His book Natural and Political Observations Made upon the Bills of Mortality (1662 Old Style or 1663 New Style) used analysis of the bills of mortality (weekly statistics of deaths) in early modern London as Charles II and other officials attempted to create a system to warn of the onset and spread of bubonic plague in the city. Though the system was never truly created, Graunt’s work in studying the rolls resulted in the first statistically based estimation of the population of London. His work ran to five editions by 1676.
The erudition of the Observations led Graunt to the Royal Society, where he presented his work and was subsequently elected a fellow in 1662 with the endorsement of the King. He was chosen as a member of the council in November 1664 and represented the society at various meetings.
His house was destroyed in the Great Fire of London and he encountered other financial problems leading eventually to bankruptcy. His daughter became a nun in a Belgian convent and Graunt decided to convert to Catholicism at a time when Catholics and Protestants were struggling for control of England and Europe, leading to prosecutions for recusancy. He died of jaundice and liver disease on 18 April 1674, aged 53.
Link to Wikipedia biography