ADOLPHE QUETELET

in 1835 first applied the normal distribution to biological and behavioral traits rather than merely to measurement error, describing the concept of "the average man"; he also invented the Quetelet Index which today we usually refer to as the Body Mass Index (BMI).

Lambert Adolphe Jacques Quetelet, b. 22 February 1796 in Ghent, French Empire, (now Belgium), d. 17 February 1874 in Brussels, Belgium

from Wikipedia:

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. He collected data about many such variables.

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) because he disagreed with Quetelet's notion that a theory of society could be derived from a collection of statistics.

...

In his 1835 text on social physics, in which he presented his theory of human variance around the average, with human traits being distributed according to a normal curve, he proposed that normal variation provided a basis for the idea that populations produce sufficient variation for artificial or natural selection to operate.

In terms of influence over later public health 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.

https://en.wikipedia.org/wiki/Adolphe_Quetelet

from Sur l'homme et le developpement de ses facultés, essai d'une physique sociale (1835) [On man and the development of his faculties: an essay on social physics]:

The constancy with which the same crimes repeat themselves every year with the same frequency and provoke the same punishment in the same ratios, is one of the most curious facts we learn from the statistics of the courts; I have stressed it in several papers; I have repeated every year: There is an account paid with a terrifying regularity; that of the prisons, the galleys, and the scaffolds. This one must be reduced. And every year the numbers have confirmed my prevision in a way that I can even say: there is a tribute man pays more regularly than those owed to nature or to the Treasury; the tribute paid to crime! Sad condition of human race! We can tell beforehand how many will stain their hands with the blood of their fellow creatures, how many will be forgers, how many poisoners, almost as one can foretell the number of births and deaths.

Society contains the germs of all the crimes that will be committed, as well as the conditions under which they can develop. It is society that, in a sense, prepares the ground for them, and the criminal is the instrument ...

This observation, which seems discouraging at first sight, is comforting at closer view, since it shows the possibility of improving people by modifying their institutions, their habits, their education, and all that influences their behaviour. This is in principle nothing but an extension of the law well-known to philosophers: as long as the causes are unchanged, one has to expect the same effects.

http://www-groups.dcs.st-andrews.ac.uk/history/Extras/Quetelet_crime.html

from Instructions populaires sur le calcul des probabilités (1828) [Popular instructions on the calculation of probabilities]:

The more advanced the sciences have become, the more they have tended to enter the domain of mathematics, which is a sort of centre towards which they converge. We can judge of the perfection to which a science has come by the facility, more or less great, with which it may be approached by calculation.

It seems to me that the theory of probabilities ought to serve as the basis for the study of all the sciences, and particularly of the sciences of observation.

Since absolute certainty is impossible, and we can speak only of the probability of the fulfillment of a scientific expectation, a study of this theory should be a part of every man's education.

Chance, that mysterious, much abused word, should be considered only a veil for our ignorance; it is a phantom which exercises the most absolute empire over the common mind, accustomed to consider events only as isolated, but which is reduced to naught before the philosopher, whose eye embraces a long series of events and whose penetration is not led astray by variations, which disappear when he gives himself sufficient perspective to seize the laws of nature.

http://www-groups.dcs.st-andrews.ac.uk/history/Biographies/Quetelet.html

from Recherches sur le Penchant au Crime aux Différens Âges (1831) [Research on the propensity for crime at different ages]:

It seems to me that that which relates to the human species, considered en masse, is of the order of physical facts: the greater the number of individuals, the more the influence of the individual will is effaced, being replaced by the series of general facts that depend on the general causes according to which society exists and maintains itself. These are the causes we seek to grasp, and when we do know them, we shall be able to ascertain their effects in social matters, just as we ascertain effects from causes in the physical sciences.

http://www-groups.dcs.st-andrews.ac.uk/history/Biographies/Quetelet.html

from Adolphe Quetelet as statistician, by Frank Hamilton Hankins (1908):

Quetelet's personality is represented as most winning. Modest and generous, convinced but respectful of others' opinions, always calm and considerate, a man of broad learning and an attractive conversationalist, he won and kept friends wherever he went. A man of excellent tact as well as of tremendous enthusiasm, he readily enlisted support for many schemes of cooperative scientific endeavor. A man of wide intellectual interests, and at the same time, endowed with a prodigious capacity for labor, he contributed to the advancement of several sciences, aroused anew the entire intellectual life of his country and stimulated the activity of artists and scientists throughout the world. Until the attack [stroke] of 1855, he is represented as always animated and genial, fond of wit and laughter. [quoting another author:] "Rabelais was almost as dear to him as Pascal."

His home life was of marked beauty and serenity. He found great pleasure in his two children, and the astronomical ability of his son [who succeeded him as Director of the Brussels Observatory] was a source of great pride to him. Quetelet was himself a modest musician, and his wife an accomplished one. Friends were regularly entertained at dinner on Sundays, and Sunday evenings were usually given over to music and charades. Personally acquainted with the leading scientists of his time, he exercised the most generous hospitality in the home at the Observatory. Distinguished men, coming to Belgium from any of the European capitals or centers of learning, brought letters of introduction to Quetelet and were always assured a gracious reception by him. One of the speakers at his funeral said of him, "as a man of science he was admired; in political affairs he was respected; in private life he was beloved."