The Haeckel-Muller biogenetic law describes the ratio observed in living nature - ontogenesis, that is, the personal development of each living organism, to a certain extent it repeats phylogeny - the historical development of the entire group of individuals to which it belongs. The law was formulated, as the name implies, by E. Haeckel and F. Müller in the 60s of the 19th century independently of each other, and now it is almost impossible to establish the discoverer of the theory.
Obviously, the biogenetic law was not formulated all at once. The work of Müller and Haeckel was preceded by the creation of a theoretical basis for the law in the form of already discovered phenomena and other established laws of nature. In 1828, K. Baer formulated the so-called law of germline similarity. Its essence lies in the fact that the embryos of individuals belonging to the same biological type have many similar elements of the anatomical structure. In humans, for example, at a certain stage of development, the embryo has gill slits and a tail. Characteristic distinctive features in the morphology of species arise only in the course offurther ontogeny. The law of germline similarity largely determined the biogenetic law: since the embryos of various organisms repeat the stages of development of other individuals, they repeat the stages of development of the entire type in general.
A. N. Severtsov later made certain amendments to the Haeckel-Muller law. The scientist noted that during embryogenesis, that is, the stage of embryonic development, there is a similarity between the organs of embryos, and not adults. Thus, the gill slits in the human embryo are similar to the gill slits of fish embryos, but in no way with the formed gills of adult fish.
It is important to note that one of the most significant evidence of Darwin's theory of evolution is considered directly biogenetic law. Its wording in itself hints at its own logical connection with the teachings of Darwin. The embryo, in the course of its development, passes through many different stages, each of which resembles certain stages in the development of nature, noted from an evolutionary point of view. Thus, each more and more complexly organized individual reflects in its ontogeny the development of all living nature from the point of view of evolution.
Psychology also has its own biogenetic law, formulated independently of the biological one. In fact, in psychology, it is not a formalized law that stands out, but the idea expressed by I. Herbart and T. Ziller about the similarity of the development of the child's psyche with that of humanity in general. Various scientiststried to substantiate this theory from different points of view. G. Hall, for example, resorted directly to the Haeckel-Muller law. He said that the development of a child, including psychologically, is set exclusively by biological prerequisites and repeats evolutionary development in general. One way or another, to date, the idea is not unambiguously proven. In psychology, there is still no biogenetic law as such.
