A London shopkeeper's tally of deaths helped launch demography
In 1662 John Graunt sifted through London's weekly Bills of Mortality and produced one of the first modern population studies. Among his findings: a third of London's children died before turning sixteen. His rough life table became the seed of the mathematics that insurance companies still use to price a lifetime.
Demography, from the Greek for people and writing, is the statistical study of human populations: how large they are, what they are made of, and how births, deaths and migration change them. Formal demography sticks to measurement, while social demography also examines the economic, cultural and biological forces behind the numbers. Its methods are flexible enough to track firms, workforces or animal populations too.
Interest in population is ancient. Greek writers from Herodotus to Aristotle and Romans such as Cicero and Pliny the Elder discussed it, medieval Christian scholars argued against classical views, and the North African historian Ibn Khaldun contributed as well. After Graunt, the astronomer Edmond Halley refined the life table into a basis for life insurance, and Richard Price produced the first textbook on life contingencies in 1771.
Population growth became a lightning rod. In 1755 Benjamin Franklin projected exponential growth in Britain's American colonies, an essay that influenced Thomas Robert Malthus. At the end of the eighteenth century Malthus warned that unchecked population would outrun food supply, bringing mounting famine and poverty, and he is regarded as the intellectual father of ideas about overpopulation and limits to growth. Benjamin Gompertz and Pierre Verhulst later offered more realistic models. The Belgian scholar Achille Guillard gave the discipline its name and a definition in 1855.
In the twentieth century Alfred Lotka, partly with F. R. Sharpe, showed in papers from 1907 to 1922 that a closed population with constant birth and death rates at each age settles into a fixed age structure, the stable population. Leonhard Euler had anticipated some of this long before, though his work was overlooked. Demographic analysis remains a benchmark for checking censuses; for 2010 the US Census Bureau expanded it to compare independent housing estimates.
Source: Demography
