Evolutionary Physiology

a branch of physiology that studies the various functions of animals in the formative stage and in the course of historical development. Evolutionary physiology investigates the evolution of functions, that is, the processes by which the functions are formed and change under the influence of external and internal factors. It also deals with functional evolution in an attempt to answer why new functional relations arise and develop in a particular way.

The emphasis on evolution in Russian physiology is linked with the research of I. M. Sechenov, N. E. Vvedenskii, and I. P. Pavlov. The term “evolutionary physiology” was coined by A. N. Severtsov in 1914. The person most responsible for the creation of Russian evolutionary physiology is L. A. Orbeli, who devised the scientific method for studying it, defined the main objectives, and outlined (in the 1920’s) the direction in which it should develop.

Orbeli, A. G. Ginetsinskii, P. K. Anokhin, and others formulated a number of general principles of functional evolution: (1) in the course of development and increasing complexity of the level of organization and establishment of new relations in the organism, the old functional relations do not disappear without a trace but remain suppressed, masked by phylogenetically younger functions; (2) the controlling influence on the nervous system increases as the organism develops; and (3) the various functional systems mature at different times in the course of individual development (seeHETEROCHRONISM).

The study of the evolution of the central nervous system (A.I. Karamian) was closely linked with the investigation of the formation and development of conditioned reflexes in animals (E. M. Kreps, L. G. Voronin, D. A. Biriukov). Comparative and developmental physiology have long been successfully developed in Britain, the United States, Denmark, Czechoslovakia, and other countries, but the standardization of research methods and the establishment of evolutionary physiology as the modern stage of physiology, based on the historical principle, are the accomplishment of Russian science.

Evolutionary physiology makes use of the findings and advances of general physiology, biochemistry, comparative morphology, genetics, and other sciences, as well as the research methods of comparative, developmental, and ecological physiology. Comparative physiology makes it possible to compare and clarify the characteristics and specific regularities of the development of physiological functions in animals belonging to different taxonomic groups. Research on functions in the embryonic and postnatal stages of ontogeny has made it possible to establish the mechanisms governing the emergence and development of functions. Evolutionary physiology also makes use of clinical data, comparing symptoms of diseases with phenomena observed in the ontogenetic or phylogenetic development of the organism. Linked to clinical research are special experimental techniques that enable scientists to disconnect organs and tissues artificially from the mechanisms that control them, as well as from the different levels of the controlling mechanisms themselves. The development of the evolutionary trend in physiology has made it possible to uncover new patterns in the functional evolution of the brain and various systems of the organism and to reveal common principles underlying the evolution of the structure and functions of the sense organs, the evolution of the musculoskeletal system, and the maintenance of homeostasis in an organism. An important objective of modern evolutionary physiology is to determine the adaptative changes that occur in functions and to study higher nervous activity in humans as it forms and develops.

In the USSR, research in evolutionary physiology is primarily conducted at the I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry (Leningrad), the A. N. Severtsov Institute of Evolutionary Morphology and Animal Ecology (Moscow), the N. K. Kol’tsov Institute of Developmental Biology (Moscow), and other institutes administered by the Academy of Sciences of the USSR. All-Union conferences on evolutionary physiology and biochemistry have been held periodically since 1956. Research results are published in the Zhurnal evoliutsionnoi biokhimii i fiziologii (since 1965) and in other journals of physiology.