Lambert Adolphe Jacques Quetelet FRSF or FRSE (; 22 February 1796 – 17 February 1874) was a Belgian

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

, mathematician, statistician and sociologist who founded and directed the

Brussels Observatory The Royal Observatory of Belgium (french: link=no, Observatoire Royal de Belgique, nl, Koninklijke Sterrenwacht van België), has been situated in the Uccle municipality of Brussels ( Belgium) since 1890. It was first established in Saint-Jos ...

and was influential in introducing statistical methods to the

social science Social science is one of the branches of science, devoted to the study of societies and the relationships among individuals within those societies. The term was formerly used to refer to the field of sociology, the original "science of s ...

s. His name is sometimes spelled with an accent as ''Quételet''. He also founded the science of

anthropometry Anthropometry () refers to the measurement of the human individual. An early tool of physical anthropology, it has been used for identification, for the purposes of understanding human physical variation, in paleoanthropology and in various atte ...

and developed the body mass index (BMI) scale, originally called the

Quetelet Index Body mass index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is expressed in units of kg/m2, resulting from mass in kilograms and hei ...

. His work on measuring human characteristic to determine the ideal ''l'homme moyen'' ("the average man"), played a key role in the origins of

eugenics Eugenics ( ; ) is a fringe set of beliefs and practices that aim to improve the genetic quality of a human population. Historically, eugenicists have attempted to alter human gene pools by excluding people and groups judged to be inferior o ...

Biography

Adolphe was born in

Ghent Ghent ( nl, Gent ; french: Gand ; traditional English: Gaunt) is a city and a municipality in the Flemish Region of Belgium. It is the capital and largest city of the East Flanders province, and the third largest in the country, exceeded i ...

(which, at the time was a part of the new French Republic). He was the son of François-Augustin-Jacques-Henri Quetelet, a Frenchman and Anne Françoise Vandervelde, a Flemish woman. His father was born at Ham, Picardy, and being of a somewhat adventurous spirit, he crossed the English Channel and became both a British citizen and the secretary of a Scottish nobleman. In that capacity, he traveled with his employer on the Continent, particularly spending time in Italy. At about 31, he settled in Ghent and was employed by the city, where Adolphe was born, the fifth of nine children, several of whom died in childhood. Francois died when Adolphe was only seven years old. Adolphe studied at the Ghent Lycée, where he afterwards started teaching mathematics in 1815 at the age of 19. In 1819, he moved to the Athenaeum in Brussels and in the same year he completed his dissertation (''De quibusdam locis geometricis, necnon de curva focal – Of some new properties of the focal distance and some other curves''). Quetelet received a doctorate in

mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

in 1819 from the University of Ghent. Shortly thereafter, the young man set out to convince government officials and private donors to build an astronomical observatory in

Brussels Brussels (french: Bruxelles or ; nl, Brussel ), officially the Brussels-Capital Region (All text and all but one graphic show the English name as Brussels-Capital Region.) (french: link=no, Région de Bruxelles-Capitale; nl, link=no, Bruss ...

; he succeeded in 1828. He became a member of the Royal Academy in 1820. He lectured at the museum for sciences and letters and at the Belgian Military School. In 1825, he became a correspondent of the Royal Institute of the Netherlands, in 1827 he became a member. In 1839, he was elected as a member of the

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

. From 1841 to 1851, he was a supernumerary associate in the institute, and when it became Royal Netherlands Academy of Arts and Sciences he became foreign member. In 1850, he was elected a foreign member of the Royal Swedish Academy of Sciences. Quetelet also founded several statistical journals and societies, and was especially interested in creating international cooperation among statisticians. He encouraged the creation of a statistical section of the British Association for the Advancement of Science (BA), which later became the Royal Statistical Society, of which he became the first overseas member. In 1853 he chaired both the International Maritime Conference and the

First International Statistical Congress The First International Statistical Congress was held on September 19, 1853 in Brussels, Belgium, with twenty-six countries in attendance. It was principally organised by Belgian astronomer and statistician Adolphe Quetelet, who envisioned a standar ...

. He was a founding member of the first ''

Société des douze The ''Société des douze'' (French; ) was scholarly and literary dining club in Brussels. The first society Its precursor, the '' Société de littérature de Bruxelles'' () founded on 10 January 1800, was deprecated by the government of ...

''. In 1855, Quetelet developed apoplexy, which diminished but did not end his scientific activity. He died in

on 17 February 1874, and is buried in the

Brussels Cemetery Brussels Cemetery (french: Cimetière de Bruxelles, nl, Begraafplaats van Brussel) is a cemetery belonging to the City of Brussels in Brussels, Belgium. Located in the neighbouring municipality of Evere, rather than in the City of Brussels pr ...

. In 1825, he married Cécile-Virginie Curtet.

Work

His scientific research encompassed a wide range of different scientific disciplines:

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

, astronomy, mathematics, statistics,

demography Demography () is the statistical study of populations, especially human beings. Demographic analysis examines and measures the dimensions and dynamics of populations; it can cover whole societies or groups defined by criteria such as ed ...

, sociology, criminology and history of science. He made significant contributions to scientific development, but he also wrote several monographs directed to the general public. He founded the Royal Observatory of Belgium, founded or co-founded several national and international statistical societies and scientific journals, and presided over the first series of the International Statistical Congresses. Quetelet was a liberal and an anticlerical, but not an atheist or materialist nor a socialist.

Social physics

The new science of

probability Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speaking, ...

and

statistics Statistics (from German: '' Statistik'', "description of a state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, indust ...

was mainly used in astronomy at the time, where it was essential to account for measurement

errors An error (from the Latin ''error'', meaning "wandering") is an action which is inaccurate or incorrect. In some usages, an error is synonymous with a mistake. The etymology derives from the Latin term 'errare', meaning 'to stray'. In statistics ...

around means. This was done using the method of least squares. Quetelet was among the first to apply statistics to social science, planning what he called "social physics". He was keenly aware of the overwhelming complexity of social phenomena, and the many variables that needed measurement. His goal was to understand the statistical laws underlying such phenomena as crime rates, marriage rates or suicide rates. He wanted to explain the values of these variables by other social factors. These ideas were rather controversial among other scientists at the time who held that it contradicted the concept of freedom of choice. His most influential book was ''Sur l'homme et le développement de ses facultés, ou Essai de physique sociale'', published in 1835 (In English translation, it is titled ''Treatise on Man'', but a literal translation would be "On Man and the Development of his Faculties, or Essays on Social Physics"). In it, he outlines the project of a social physics and describes his concept of the "average man" (''l'homme moyen'') who is characterized by the mean values of measured variables that follow a

normal distribution In statistics, a normal distribution or Gaussian distribution is a type of continuous probability distribution for a real-valued random variable. The general form of its probability density function is : f(x) = \frac e^ The parameter \mu ...

. He collected data about many such variables. Quetelet wrote about these values as "ideals" with deviations from them as being less than or more than ideal. He saw the average body as an ideal beauty and something to be desired and his work was influential on Francis Galton who coined the term ''eugenics''. Quetelet's student Pierre François Verhulst developed the logistic function in the 1830s as a model of population growth; see for details. When Auguste Comte discovered that Quetelet had appropriated the term 'social physics', which Comte had originally introduced, Comte found it necessary to invent the term 'sociologie' (

sociology Sociology is a social science that focuses on society, human social behavior, patterns of social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of empirical investigation an ...

) because he disagreed with Quetelet's notion that a theory of society could be derived from a collection of statistics. Adolphe Quetelet also had a significant influence on

Florence Nightingale Florence Nightingale (; 12 May 1820 – 13 August 1910) was an English social reformer, statistician and the founder of modern nursing. Nightingale came to prominence while serving as a manager and trainer of nurses during the Crimean War ...

who shared with him a religious view of statistics which saw understanding statistics as revealing the work of God in addition to statistics being a force of good administration. Nightingale met Quetelet in person at the 1860 International Statistical Congress in London, and they corresponded for years afterwards.

Criminology

Quetelet was an influential figure in criminology. Along with Andre-Michel Guerry, he helped to establish the cartographic school and positivist schools of criminology which made extensive use of statistical techniques. Through statistical analysis, Quetelet gained insight into the relationships between

crime In ordinary language, a crime is an unlawful act punishable by a state or other authority. The term ''crime'' does not, in modern criminal law, have any simple and universally accepted definition,Farmer, Lindsay: "Crime, definitions of", in C ...

and other social factors. Among his findings were strong relationships between age and crime, as well as gender and crime. Other influential factors he found included

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...

, poverty,

education Education is a purposeful activity directed at achieving certain aims, such as transmitting knowledge or fostering skills and character traits. These aims may include the development of understanding, rationality, kindness, and honesty ...

, and alcohol consumption, with his research findings published in ''Of the Development of the Propensity to Crime''.

Anthropometry

In his 1835 text on social physics, he presented his theory of human variance around the

average In ordinary language, an average is a single number taken as representative of a list of numbers, usually the sum of the numbers divided by how many numbers are in the list (the arithmetic mean). For example, the average of the numbers 2, 3, 4, 7 ...

, showing human traits were distributed according to a normal curve. The existence of such variation provided the basis for later writers, including Darwin, to argue that natural populations contained sufficient variability for

artificial Artificiality (the state of being artificial or manmade) is the state of being the product of intentional human manufacture, rather than occurring naturally through processes not involving or requiring human activity. Connotations Artificiality ...

natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Cha ...

to operate. In terms of influence over later

public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...

agendas, one of Quetelet's lasting legacies was the establishment of a simple measure for classifying people's weight relative to an ideal for their height. His proposal, the body mass index (or Quetelet index), has endured with minor variations to the present day.Garabed Eknoyan (2008)
"Adolphe Quetelet (1796–1874) – the average man and indices of obesity".
In: ''Nephrol. Dial. Transplant''. 23 (1): 47–51. Anthropometric data is used in modern applications and referenced in the development of every consumer-based product.

Awards and honours

Quetelet was elected a Foreign Member of the Royal Society (ForMemRS) in 1839. The asteroid 1239 Queteleta is named after him. The title of Quetelet professor at

Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...

is awarded in his name.

Publications

* 1823. ''Relation d'un voyage fait à la grotte de Han au mois d'août 1822'. 'With M.M. Kickx. * 1827. ''Recherches sur la population, les naissances, les décès, les prisons, les dépôts de mendicité, etc., dans le royaume des Pays-Bas''. * 1829. ''Recherches statistiques sur le royaume des Pays-Bas''. * 1831. ''The Propensity to Crime''. * 1834. ''Astronomie élémentaire''. * 1835. ''Sur l'homme et le développement de ses facultés, ou Essai de physique sociale''. 2 volumes. * 1838. ''De l'influence des saisons sur la mortalité aux différens âges dans la Belgique''. * 1839. ''Catalogue des principales apparitions d'étoiles filantes''. * 1842. ''A Treatise on Man and the Development of His Faculties''. * 1843. ''Sur l'emploi de la boussole dans les mines''. * 1845–1851. ''Sur le climat de la Belgique''. 2 volumes. * 1848. ''Du système social et des lois qui le régissent''. * 1848. ''Sur la statistique morale et les principes qui doivent en former la base''. * 1850. ''Mémoire sur les lois des naissances et de la mortalité à Bruxelles''. * 1853. ''Mémoire sur les variations périodiques et non périodiques de la température, d'après les observations faites, pendant vingt ans, à l'observatoire royal de Bruxelles''. * 1864. ''Histoire des sciences mathématiques et physiques chez les Belges''. * 1867. ''Météorologie de la Belgique comparée à celle du globe''. * 1867. ''Sciences mathématiques et physiques au commencement du XIXe siècle''. * 1869. ''Sur la physique du globe en Belgique''. * 1870. ''Anthropométrie, ou Mesure des différentes facultés de l'homme''.