How did John Graunt use London’s bills of mortality to study population patterns?

John Graunt, often recognized as the founder of demography, revolutionized the study of human populations by analyzing the bills of mortality—weekly records of deaths and baptisms kept by London parishes since the 16th century.12

By identifying statistical regularities in these records, Graunt performed several pioneering analyses:

• Sex Ratios: He observed that while male birth rates were higher than female, a greater male mortality rate resulted in a nearly even distribution between the sexes.12
• Urban vs. Rural Trends: He noted that urban death rates were higher than those in rural areas.1
• Population Estimation: By examining birth and death rates, he estimated the total population of London, the number of families, and the number of individuals of military or childbearing age.2
• Life Tables: His most significant innovation was the construction of the first life table, which used survivorship data to predict life expectancy and the percentage of people surviving to successive ages.1

His findings, published in Natural and Political Observations... Made upon the Bills of Mortality (1662), established the foundation for modern vital statistics.12