The problem of norm in biological and medical sciences

Abstract

The article reviews various approaches to the problem of morm definition and establishment. A wide variability of definitions and approaches as well as their specifical character related to divergence among disciplines is stressed by the author. The first part of the paper deals with history of the notion „norm” during development of biology, medical sciences and philosophy. Other parts deal with theoretical bases of normology, statistical criterions of biological norm, selected interpretations of the notion of biological norm and problems of norm in medicine. The author shows that evolution of the notion „norm” in biological and medical sciences may be divided into three stages. The first one was empirical. During this stage, confined mainly to antiquity, were undertaken attempts at establishing ideal norms of beauty in arts and aesthetics and on the other hand descriptions made of various physical anomalies percieved as examples of deviations from some „norm”. Such understandings of „norm” survived to our day. During this first stage such persons as Aristotle, Plato and later on Kant and Leibniz were dealing with the problem of normalacy. The second stage consisted of typological approaches to the probiem. Theoretical bases for such approaches were supplied by classical genetics and sophisticated statistical methods used in biology (biometrical methods). Typological concepts of norm were based mainly on abstract arithmetic means of biological characters and assumed stability of norms through time. During this stage appeared systems of constitutional typology (somatotypology), such as Kretschmer's or Sheldon's systems of classification, and racial typologies. Mathematical accuracy to the racial typology was given by J. Czekanowskis anthropological school. However, abstract numerical characteristics of the „types” fitted with enough accuracy only a small fraction of people. Typological systems were strongly criticised for their inaccuracy and abstract character leading to doubts about real existence of such norms. The author describes views of Williams, Durkheim, Kneucker and King in relation to the second stage. The third stage of the concept development is based on synthetic theory of evolution — notions of adaptation norm and norm of reaction. Statistical measure of normalacy is no longer arithmetic mean, but variance — expression ofi normal variability (Smith, Mayr, Johnston). The most convincing method of establishing biological norms for living systems becomes search for functional optimum for those systems. Grounds for such an approach were created by Bernard, Cannon, Seyle who constructed the theory of homeostasis. From populational concepts stems transient character of biological norms — they do not characterize a given frozen state but a temporal process. Hence norms change along with temporal changes of life. Furthermore, specific character of individual, group and general norms is emphasised. On grounds of notion of health and of ilness a problem of norm is dealt with in medical sciences. The author stresses that, as has been shown by Korolkov & Petlenko, in theoretical medicine it is necessary to pay more attention to results of theoretical biology based on the synthetic theory of evolution.