Bertillon was educated as a physician before he turned his attention to statistics, but he invariably applied his statistics techniques to problems of a social nature. Clark writes :-
Jacques Bertillon was one of the most prolific and influential quantitative social scientists in France near the turn of the century. His work grew out of a tradition pioneered by Adolphe Quetelet and developed by Bertillon's grandfather, Achille Guillard, and father, Louis-Adolphe Bertillon.Some of Bertillon's early statistical work involved comparative studies of divorce rates and suicide rates between different countries which he published in Annales de démographie internationale; he became the editor of the journal in 1882. In La Nature he published articles such as Ouverture des cours d'anthropologie Ⓣ (1877), Statistique des bègues en France Ⓣ (1880), Influence du mariage sur la tendance au suicide Ⓣ (1880), and Nains et Géants Ⓣ (1880). Also in 1880 he published a major work entitled La Statistique humaine en France Ⓣ. In 1883 Bertillon's father, Louis-Adolphe, died and Jacques Bertillon succeeded him as director of the Bureau de Statistique Municipale in Paris; he held this post for thirty years until 1913. In the same year of 1883 he published another major work Étude démographique du divorce et de la séparation de corps dans les différents pays de l'Europe Ⓣ. In 1896 he published Cours élémentaire de Statistique administrative Ⓣ to improve the methods of collecting data by French government offices. Falkner, in the review  writes:-
It must have been an extreme modesty or a very generous conception of the limits of statistical science which lead the author to characterise his book as an elementary one. We should be inclined to designate it as a most elaborate treatment of the subject. The point of view which distinguishes his treatment is the administrative character of statistical investigation, and the object with which it was prepared was to place in the hands of those who present themselves as candidates for the public service in France, a suitable guide through the labyrinth off the statistical work of the government. It appeals, therefore, in the first instance to the French. It appeals to others through the fact that its pages give a precise and definite account of the statistical activity of a typical modern nation and through its admirable treatment of the more general aspects of statistical work.A study of the causes of death led him to introduce the 'Bertillon classification'. He first introduced it at the Chicago Conference of the International Statistical Institute in 1893. His classification was adopted by the American Health Association in 1897 and then it was approved as the international standard by an International Commission in Paris in 1900. In 1895 he founded the Free College of Social Sciences in Paris and he taught statistics and demography there for more than ten years. He was also Professor of Demography at the École d'Anthropolie. From 1879 he was a member of the Statistical Society of Paris and in 1897 he was elected president of the Society. During World War I he was head of medical-surgical statistics for the French army, collecting and studying the statistics of disease among the French soldiers, and he established an inventory of injuries and illnesses at all hospitals.
There were two topics which became the most important for Bertillon :-
Bertillon was a deeply patriotic Frenchman with strong social convictions. Through his statistical work, he became aware of the extent of two phenomena which he came to consider as the most serious social problems that France had to face: alcoholism and "depopulation." Attempting to develop a more thorough understanding of each of these phenomena, he undertook careful analyses of the statistics available on them.As to alcoholism he wrote several works perhaps the most significant being in 1904 when he published L'Alcoolisme et les moyens de le combattre jugés par l'expérience Ⓣ. His attempts to combat depopulation included publications such as the major book La dépopulation de la France, ses conséquences, ses causes, mesures à prendre pour la combattre Ⓣ (1911), the founding of the Alliance nationale pour l'accroissement de la population française Ⓣ in 1896, and the founding of the bi-weekly journal La femme et l'enfant in 1918. What did he think were the reasons for the decline in the population of France? He suggests that high taxation and small apartments both were factors in parents deciding to have few children. Among his suggestions to combat the decline was a proposal that parents should receive a cash bonus for their fourth child. The arguments that he put to the French government, mostly through the Conseil Supérieur de la Natalité, led to the passing of a law in 1920 which made it illegal to give information about methods of birth control. Of course, Bertillon was well known to members of the government being on various bodies such as the Higher Council of Statistics, which advised the government on statistical matters, and the Committee on Public Hygiene.
He also put forward arguments, backed up by statistical studies, encouraging men and women to marry :-
Marry if you want to live to a good age. The married man or woman has thrice as much chance of a good, long run of life as a bachelor or spinster. To you, Monsieur, I say marry and you will do well even from a selfish standpoint; but watch carefully over your wife's health as, even from this egotistical point of view, her loss will be a terrible misfortune; for your life depends in a great measure on her own. And to you, Mademoiselle, I give counsel to marry in your most selfish interest, as mortality among married women is less than among spinsters of the same age, at least after the age of 20 ... Mortality among widows is distinctly much greater than among married women of the same age. 'The sweet state of widowhood' is, on the contrary, fatal to young widows. Their death rate, from 20 to 25 years of age, is twice that of married women at the corresponding age. ... Married people lead a more regular life. They are more controlled, discreet though this control may be, and it must be discreet if it is to be useful. Their physical life, like their moral life, is healthier, quieter, and more natural. Other explanations may be assigned but, in my opinion, they are not worth this one.Certainly not all of Bertillon's arguments have been accepted. Riley, in , gives an example where Bertillon has failed to take into account certain relevant facts:-
Jacques Bertillon compared sickness and death rates from several countries in 1892, finding that sickness rates in the British friendly societies were higher than those in counterpart sick funds in France and Italy. He reasoned from analogy: mortality rates were similar in the three countries, hence morbidity rates should be similar. Since they were not, he expressed doubt about the reliability of the sickness rates reported for the British friendly societies. Bertillon also ventured a guess about why sickness rates were higher in English societies: those societies were richer and thus better able to pay benefits. ... But Bertillon is guilty of being systematically inattentive to the significant details of the thing he purported to study. Specifically, he neglected the following important differences, with the result that he grossly understated sickness rates in the continental societies.Riley then makes five points which Bertillon has overlooked, the first being:-
The French and Italian societies paid benefits only for the first six to nine months of an episode of sickness, rather than for an indefinite period, as most British friendly societies did, albeit often at a reduced rate. Hence they omitted protracted sicknesses, except in their early stages.We should also mention another important contribution made by Bertillon in collaboration with his brother Alphonse Bertillon who was in the Police Force. Together they developed anthropometry, an identification system based on physical measurements which was used by police to identify criminals. Later Bertillon invented the fingerprint system but it was his brother Alphonse who saw the practical implementation and use by the police.
Among the many honours given to Bertillon, let us note that the Vital Statistics Section of The American Public Health Association unanimously adopted the following at its meeting in New York City on 18 November 1921:-
Dr Jacques Bertillon, Paris, France.In  his death is reported as follows:-
Whereas, Dr Jacques Bertillon has served for over twenty years as the Secretary General of the International Commission which has recently made the third decennial revision of the International List of Causes of Death,
Whereas, Dr Jacques Bertillon is recognised the world over as the father of international nosologic nomenclature,
Whereas, Dr Jacques Bertillon, though in ill health, has recently carried through successfully the arduous labours connected with the third decennial session of the Commission already referred to,
Be it resolved, that the Vital Statistics Section of The American Public Health Association express to Dr Jacques Bertillon, Secretary General of the International Commission for the Revision of the International List of Causes of Sickness and Death, appreciation of his untiring efforts to procure comparable international statistics of sickness and mortality, and extend to him the good wishes of the Association for his rapid and complete recovery.
Paris July 7.- Dr Jacques Bertillon, the famous criminologist, died here today. Obituaries printed in the Paris newspapers this afternoon were written by the aged savant himself several days ago.
Article by: J J O'Connor and E F Robertson