**BIOMETRY (ANTHROPOMETRY).** —
I. ORIGINS AND DEFINITION
Biometry arose at the historical moment when the life sciences, in general, began to replace the qualitative method with the quantitative one, when the concepts of large or small, long or tall, light or heavy, dense or fluid were being rendered measurable. This was the direction taken at the end of the 16th century and even more so in the 17th, with the great works of Descartes and Francis Bacon of Verulam, if one does not wish to cite Galileo himself as the true founder of the new method of scientific inquiry. In this atmosphere, the quantitative method was also being introduced into the systematic study of living beings. Santorio Santorio of Capodistria (1561–1636) is perhaps the initiator of such research and founder of a genuine school that had a wide impact on all medicine of the time, especially in England (with the so-called iatromathematics). Thus began the measurement of the most diverse functions and characteristics of the healthy and diseased human organism, while concepts such as the normal (average) intensity of each biological phenomenon studied, variability, and reciprocal connections among them were introduced. Over time, the methods of metric survey were simplified, whereas, for example, Santorio had counted pulse frequencies with a special pendulum inspired by the work of his colleague Galileo. In this regard, mention should be made of the English physician John Floyer (1649–1734) with his two volumes of *Symptomatic Therapy*: his contribution remains interesting for the method, having constructed an apparatus to measure pulse frequency.Under other aspects, many authors’ names should be recalled whose works helped give biometry its identity as a science. Captain John Graunt (1620–74) formulated the first biological interpretations of major demographic phenomena, thus giving rise to a new chapter of science that measures births and deaths and reveals the laws of natural population development. To the Belgian Adolphe Quetelet (1796–1874) is owed the credit for founding modern anthropometry. However, the development of research was slow, and truly new contributions came from the Moravian monk Gregor Mendel (1822–84) and the Englishman Francis Galton (1822–1911), founder of the biometric school in English and of the famous journal *Biometrika*, later directed by K. Pearson and still published today.
From these precedents, the quantitative survey method has increasingly extended to the solution of the most varied biological problems, so that today one speaks of biometry as a science, distinguishable into human biometry (anthropometry), animal biometry, and plant biometry. Some authors, however, propose other subdivisions that are either merely formal or based on the technique employed in surveying and processing data. In a scientific context, a general definition of biometry might be formulated as “the discipline that statistically investigates the state, consistency, natural and social movement of populations, the forms, functions, and psychology of living organisms.” Thus, organisms are considered not only as forming populations but also from the standpoint of their individual characteristics. The conception is in reality very broad, and attempts have been made repeatedly to limit its scope, but this is erroneous if it leads to an arbitrary fragmentation of research, similar to what occurs in biology. Indeed, in the sense outlined, biometry proves to be biology itself treated according to the principles of modern statistics; the distinction is therefore based solely on the technical approach to survey and data processing, not on the nature of the problems studied, which are always biological. For this reason, it might be desirable—at least in theoretical, if not didactic, contexts—to dispense with the distinction between biometry and biology. The issue is formally only apparent, but in practice, the errors scattered in the literature can be explained because biometric research has often been conducted without adequate preparation in biological problems, or conversely, without sufficient knowledge of statistical technique, its possibilities, and its pitfalls.
Given this, biometry should be regarded as a true science and thus must aim not only at the discovery of truth but of truth in natural laws. Too often, metric surveys have been conducted without a precise biological objective to achieve: one might say when they are justified only by the empirical observation of measuring a dimension or an angle, etc., to study, for example, racial or group differences. But once differences are found (and they will always be found within the realm of life!), the rest has been neglected or entrusted to some intuitive interpretation. This is not the result of such inquiry. If anything, intuitive interpretation could most often be formulated a priori, before measurements, before any mass observation. Thus, what remains of the inquiry are mere differences, not constant or normal relationships, let alone biological laws toward which biometry can and must strive. Conceived in this way, biometry assumes a proper character as an experimental science. Its quantitative method should be regarded as a valuable working tool, not as an end in itself for the biologist. Moreover, it should be noted that the development of research requires neither advanced mathematics nor excessive abstraction from the practical biological problem, but rather a mindset suited to quantitative judgment, even of facts recorded qualitatively and merely cataloged. This has been demonstrated especially in research on the morphological variability of the human brain and, in the field of psychology, in the processing of results obtained from mental tests.
II. Principal Results
If one were to attempt a systematic and comprehensive treatment of all biometry, it would appear disjointed in its parts, perhaps unharmonious, with numerous discontinuities, precisely because of its failure to be incorporated into biology, of which it is an integral part as a science (if not in its technique). But this is only an apparent disharmony that would lead us down the path already taken by biologists in various specialized fields, with the rigorous methods of work and interpretation derived from the mathematical and statistical sciences, from the examination and investigation of the laws of growth of cells and tissues, to the biological interpretation of the natural movement of populations, to the study of biocenotic equilibria, to demogenetics, to the study of the variability of human, animal, and plant characteristics, to problems of sex from a biometric perspective, and to practical studies of yields in the fields of animal husbandry and plant cultivation. The main results obtained so far have shown that at the present time we should above all abandon the old procedure by which, once a more or less vague theory was formulated, all possible confirmations were sought in every field. Instead, we should devote ourselves to the direct solution of the many biological problems that present themselves daily, at the pure source of observation and experience, abandoning “the sublime pretensions of origins and principles, from which the entire science of nature was to be deduced” (from the inaugural address by Salvatore Tommasi for the academic year 1866 at the University of Naples).Schematically, the essential chapters of biometry (especially human biometry) deal with the following topics:
1. Evolution and selection of groups (laws of development, natality, mortality, historical theories on the doctrine of species, etc.);
2. Genetics (phenogenetics, hybridism, multiple factors, norm of reaction, human eugenics, etc.);
3. Demogenetics (which studies the nature of similarities and differences among natural groups or complexes of organisms and their respective lineages, according to A. Sacchetti, judging the inheritance of traits in accordance with the different systematic hierarchy of the group under examination);
4. Growth, mean, and variability of traits (which includes morphological, physiological, and psychological traits of all categories of individuals, hence the emergence, for example, of comparative criminology, psychometry of the deceased, and so on);
5. Practical classification of races (for which the biometric and demogenetic methods are widely employed);
6. Constitutions (within the so-called biotypology, according to Pende, which addresses many problems from an anthropometric perspective, such as the balance of circulating hormones, the morphological classification of types, the correlation between individual traits, etc.).