Biometry

BIOMETRY (from Greek bios—life and metron—measure), a branch of biology that uses methods of mathematical statistics to study heredity, variability, and a whole range of other biological phenomena associated with life processes (e.g., in physiology, medicine, biochemistry, etc.). The very word biometry (in English, biometry) was introduced into science by F. Galton in 1889; from this year begins the rapid development of biometry thanks to the works of Galton himself, and subsequently K. Pearson and their students, who grouped around the journal «Biometrika» published by Pearson. Being on the border of two sciences—mathematics and biology—biometry cannot be regarded as an independent science, because it has neither its own special object of study nor its own independent methods. Applying certain methods of variation statistics to corresponding biological phenomena (see), biometry is based on the theory of probability and, in particular, on the theory of errors. Any biological phenomenon that fluctuates in its manifestation and yields non-identical but variable results upon study (where the magnitude of these fluctuations can be measured) becomes an object of biometric analysis. Thus, at the basis of biometric study, as a statistical method, lie the measurement and counting of biological phenomena. In a whole range of other biological questions, especially in the study of heredity (see), phenomena of mass variability, and others, biometric analysis renders invaluable services to biology, bringing clarity and precision where previously rule of thumb and «eyeball» estimation reigned. Penetrating with its method of «number and measure» into the most diverse fields of biological knowledge, biometry fulfills Galileo's behest: to measure everything measurable and to make measurable that which is not yet amenable to measurement. But the position of biometry on the border of two such different sciences as mathematics and biology harbors the source of many errors and infatuations. For its correct application, it requires an equal degree of competence both in the field of biometry and in the corresponding branches of mathematics, and such a combination, unfortunately, is far from frequent. As a result, the history of biometry shows a number of cases where it led biology into a blind alley. The reason lay in the fact that the solution of biological problems using biometry was undertaken either by biologists who overestimated the power of biometric analysis and made excessive demands on biometry, or, conversely, by mathematicians who were very strong in mathematical statistics but incompetent in the biological side of the problems they undertook to solve (Galton, Pearson—especially in the field of heredity). Hence arose the fact that a essentially statistically correct description of a phenomenon received a completely incorrect biological interpretation in their works. In general, the entire history of biometry testifies to the fact that a formally mathematical attitude toward biometric analysis has more than once led biology onto a false path and, in any case, has contributed extremely little to the elucidation of biological phenomena. Immeasurably more fruitful was the direction of biometry (represented by Heinke, Johannsen, and others) which sees in the biometric method merely a tool that directs and controls the purely biological analysis of phenomena. In this regard, Johannsen's words are profoundly true: «Biological problems must be solved with the aid of mathematics, but not as mathematical problems»; see Variation statistics.