BIOMETRIA (ANTHROPOMETRY). -
I. ORIGINS AND DEFINITION
B. arose at the historical moment when, in the life sciences generally, the qualitative method was beginning to be replaced by the quantitative one, that is, when there was a tendency to make the concepts of large or small, long or tall, light or heavy, dense or fluid measurable. This was in fact the direction that emerged at the end of the sixteenth century and, even more so, in the seventeenth, with the great works of Descartes and Bacon of Verulam, if one does not wish to cite Galileo himself as the true founder of the new method of scientific investigation. In this atmosphere, the quantitative method was also being introduced into the systematic study of living beings. Santorio Santorio da Capodistria (1561-1636) was perhaps the initiator of such research and the founder of a genuine school that had a broad impact throughout the medicine of the period, especially in England (with the so-called iatromathematics). Thus people began to measure the most diverse functions and characteristics of the healthy and diseased human organism, while introducing the concepts of the normal (mean) intensity of each biological phenomenon studied, as well as those of their variability and reciprocal connection. With time, methods of metric measurement were also simplified, whereas, for example, Santorio had counted pulse frequencies with a special pendulum inspired by the work of his colleague Galileo. In this connection, mention should be made of the English physician Giovanni Floyer (1649-1734), with his two volumes of Symptomatic Therapy: as regards method, his contribution remains of interest, since he constructed an apparatus for measuring pulse frequency.From other points of view, many authors whose works helped to give b. its individuality as a science ought to be remembered. Captain Giovanni Graunt (1620-74) formulated the first biological interpretations of the principal demographic phenomena, thus giving rise to a new chapter of science that measures births and deaths and determines the laws governing the natural development of populations. The Belgian Adolfo Quetelet (1796-1874), on the other hand, deserves credit for founding modern anthropometry. However, the development of research was slow, and genuinely new contributions came from the Moravian monk Gregorio Mendel (1822-84) and the Englishman Francesco Galton (1822-1911), founder of the English biometric school and of the famous journal Biometrika, later directed by K. Pearson and still published today.
On the basis of these antecedents, the method of quantitative measurement has been extended ever more widely to the solution of the most diverse biological problems, so that today one speaks of b., as a science, distinguishable into human b. (anthropometry), animal b., and plant b. Some authors, however, propose other subdivisions which, in fact, are either merely formal or are based on the technique followed in measuring and processing the data. In scientific terms, a general definition of b. might be formulated as that “discipline which investigates statistically the state, composition, natural and social movement of populations, and the forms, functions, and psychology of living organisms.” Thus organisms are considered not only insofar as they form populations but also from the standpoint of their individual characteristics. The conception is in fact extremely broad, and consequently attempts have repeatedly been made to restrict the subject; but this is mistaken if it leads to an arbitrary fragmentation of research, as happens similarly with biology. Indeed, in the sense described, b. proves to be biology itself treated according to the principles of modern statistics; the distinction is therefore based solely on the technical approach to measuring and processing data, not on the nature of the problems to be studied, which are always biological. For this reason, it might perhaps be desirable that, at least in theory, if not for teaching purposes, the distinction between b. and biology should be abolished. The issue is only apparently formal; in practice, however, the errors scattered throughout the literature can be explained by the fact that biometric research has often been conducted without adequate preparation concerning the biological problem, or conversely without sufficient knowledge of statistical technique, its possibilities, and its dangers.
This being established, b. must be regarded as a genuine science and must therefore aim not merely at the pursuit of truth, but at truth in the natural laws. Far too often metric measurements have been undertaken without any precise biological objective to be attained: that is, when they were justified only by the empirical observation involved in recording a measurement or an angle, etc., in order, for example, to study racial or group differences. But once the differences had been found (we shall always find them within the sphere of life!), everything else was neglected or entrusted to some arbitrary intuitive interpretation. And this is not the result of such an investigation. If anything, the intuitive interpretation could most often have been formulated a priori, before the measurements and before any mass observation. Thus the investigation yields nothing but simple differences, not constant or normal relationships, and still less biological laws—whereas b. can and must strive toward these. Conceived in this way, it assumes the proper character of an experimental science. Its quantitative method must therefore be regarded as a precious working instrument, not as an objective of investigation for the biologist. It should also be noted that the development of research requires neither higher mathematics nor excessive abstraction from the practical biological problem, but rather a forma mentis suited to quantitative judgment, even when dealing with facts recorded qualitatively and merely catalogued. This has been demonstrated above all by research on the morphological variability of the human brain and, within psychology, by the processing of results obtained from mental tests.
II. PRINCIPAL RESULTS
If one attempted an organic and summarizing treatment of the whole of b., it would appear disjointed in its parts, perhaps disharmonious, with numerous breaks in continuity, precisely because of its aforementioned failure to be incorporated into biology, of which it is an integral part as a science (if not in its technique). But this disharmony is only apparent; it would lead us along the path already followed by biologists in the various specialized fields, with the rigorous method of work and interpretation that comes to us from the mathematical and statistical sciences: from the examination and investigation of the laws governing the growth of cells and tissues, to the biological interpretation of the natural movement of populations, the examination of biocentric equilibria, demogenetics, the study of the variability of human, animal, and plant traits, problems of sex from the biometric point of view, and the practical study of yields in the fields of animal husbandry and crop production. The principal results obtained thus far have shown that, at the present time, we ought above all to abandon the old procedure whereby, having formulated a more or less vague theory, one proceeded to seek all possible confirmations of it in every field. Rather, we should devote ourselves to the direct solution of the many biological problems that present themselves to us each day, drawing upon the purest source of observation and experience, and abandoning “the sublime pretensions of origins and principles, from which the whole of the science of nature was to be deduced” (from Salvatore Tommasi’s inaugural address for the year 1866 at the University of Naples).Schematically, the essential chapters of b. (especially of human b.) deal with the following subjects:
1. Evolution and selection of groups (laws of development, birth rate, mortality, historical theories concerning the doctrine of species, etc.);
2. Genetics (phenogenetics, hybridisms, multiple factors, reaction norm, human eugenics, etc.);
3. Demogenetics (which studies the nature of the similarities and dissimilarities among groups or natural complexes of organisms and their respective lines of descent, according to A. Sacchetti, assessing the heredity of traits in accordance with the different systematic hierarchy of the group under examination);
4. Growth, means, and variability of traits (including morphological, physiological, and psychological traits of all categories of individuals; hence, for example, there have arisen a comparative criminology, a psychometrics of the deceased, and so forth);
5. Practical classification of races (for which extensive use is made of the biometric and demogenetic method);
6. Constitutions (within the sphere of so-called biotypology, according to Pende, which addresses many problems from the anthropometric point of view, such as the equilibrium of circulating hormones, the morphological classification of types, the correlation among individual traits, etc.).