Who was Adolphe Quetelet?
Born in Belgium in 1796, Quetelet early revealed a talent for the sciences in combination with a deep interest in the humanities, including the performing arts, painting, and poetry. After receiving his doctorate in mathematics from the University of Ghent at age 23, he went to Paris to study probability theory with Laplace, Fourier, and Poisson. Returning to Brussels, he founded the Royal Astronomical Observatory in 1828, which he directed for several years. During his career, he made important contributions to a wide range of disciplines: meteorology, astronomy, mathematics, statistics, demography, sociology, criminology, and the history of science.1
Quetelet explored relationships not only among celestial bodies but within human and social bodies, ie, societies. He took many anthropometric measurements and pioneered the statistical investigation of social behaviors, studying their distributions and averages. He systematically collected data on births, deaths, and crimes and contributed to the methods of population censuses.
In a famous 1835 essay,2 Quetelet introduced the notion of the homme moyen (“average man”), combining the social and physical characteristics of populations. Such patterns, he argued, could be explained by “the general causes for which society exists and maintains itself.” He believed that the “science of man” should investigate the “social body,” and not the “particularities distinguishing the individuals composing it.”2
Quetelet's influential work was amplified by the English school of social biometrics in the early 20th century.1 He believed that statistical laws explained social phenomena, and that as civilization developed, the “average man” would be ever more closely approximated. This vision ignited heated debates about free will versus social determinism in the new disciplines of sociology and political economy.3
A cosmopolitan citizen–scientist, Quetelet actively fostered cooperation across the scientific community. He organized the first international statistical meetings and journals1 and was active in several Belgian and Europe-wide scientific societies. He became a private tutor to Prince Albert, Queen Victoria's consort; his perspectives may have influenced Prince Albert's political views. He frequently gave lectures aimed at general audiences, and kept a roster of >2,500 correspondents. With Malthus, he discussed population trends; with Goethe, he debated philosophical issues; and with US President Garfield, he consulted about improving the US census.4 Quetelet died in 1874, 5 days shy of his 78th birthday.
Despite Quetelet's numerous contributions to physical and social sciences—all relevant to public health and epidemiology—he is not generally considered among the founders of the field. He left his mark on public health, nonetheless. In proposing a body mass index (weight [kg]/height [m]2), Quetelet provided a way to quantify the relationship between a person's life course weight and height, starting from the premise that “the transverse growth of man is less than the vertical.”2 His measure was so insightful and practical that it endures to this day as the most widely used indicator of obesity, a leading cause of disease and death in human populations.
1. Eknoyan G. Adolphe Quetelet (1796–1874)—the average man and indices of obesity. Nephrol Dial Transplant. 2008;23:47–51.
2. Quetelet A. Sur l'homme et le development de ses faculties, ou Essai de physique sociale. Vol 2. Paris; 1835.
3. Mosselmans B. Adolphe Quetelet, the average man and the development of economic methodology. Euro J Econom Thought. 2005;4:565–582.