Many have come across such a concept as the biogenetic laws of development, but few can explain their meaning. Now this term is rarely used because of the criticism of modern scientists. What is the essence of biogenetic law? Briefly, this concept can be described as follows: each living organism in its development passes to a certain extent the same stages as its ancestors.
For the first time the biogenetic law was formulated by Charles Darwin in his famous work "The Origin of Species", published in 1859. However, its wording was rather vague. Ernst Haeckel, a famous German scientist who introduced such terms as ontogenesis, ecology, phylogenesis and some others, as well as his theory of the origin of multicellular organisms, gave a clearer definition of the concept of biogenetic law of development.
The formulation of Haeckel stated that the ontogenesis of an organism is a repetition of phylogenesis, that is, the historical development of organisms of the same species. Biogenetic law for a long time called the "law of Haeckel," as a tribute to a brilliant scientist.
Regardless of Haeckel, another German naturalist, Fritz Muller, formulated his own definition of biogenetic law in 1864.
Relationship with evolutionary theory
The modified definition of a biogenetic law, according to which one species can acquire traits of a species that existed previously, confirms evolutionary theory. Due to the reduction of the stages of ontogenesis and arkhallaksis, the body acquires some features characteristic of its long-time ancestors, but it cannot acquire all the signs peculiar to them. This confirms the second law of thermodynamics for living organisms (the impossibility of spontaneous reduction of entropy in an open system) and the law of irreversibility of evolutionary processes (the restoration of signs lost during the evolutionary process is impossible).
Biogenetic law in the form in which it was formulated by Ernst Haeckel, has been subjected to harsh criticism from researchers. Most scientists found the arguments of colleagues unprovable. At the end of the 19th century, when researchers wanted to find out what the essence of the biogenetic law was, they discovered some contradictions and inconsistencies with the truth. From observations and experiments it became clear that ontogenesis is not complete, but only partly repeats the stages of phylogenesis. An example of this is the neoteny phenomenon - the reduction of ontogenesis and the precipitation of its separate stages. Neoteny is characteristic of ambist larvae, the axolotl, which, due to their individual hormonal characteristics, reach puberty at the larval stage.
The concept of reverse neoteny, anabolism, is defined as the lengthening of ontogenesis, the appearance of additional stages in the development of the organism. With this form of ontogenesis, the embryo actually goes through the same stages of development as its adult ancestors. However, anabolic conditions do not exclude the possibility that, at a late stage of development, ontogenesis will not go the other way and the body will not acquire certain differences from adult individuals of its own species. That is, the complete repetition of all stages of development of the ancestors of the same species is impossible, since the ontogeny of the organism occurs under the influence of various factors (environmental exposure, spontaneous mutations in the genome), and not only through the implementation of genetic material.
The Russian biologist A. Severtsov introduced the term arkhallaksis, a change in ontogenesis in which the earliest stages of development of an organism differ from the phylogenesis of its ancestors. It is obvious that the recapitulation (repetition) of signs characteristic of adults of the same species is impossible, and the body acquires new signs that were not previously characteristic of its type.
It became clear from a number of scientific studies that the biogenetic law formulated by Haeckel has many exceptions and contradictions. The scientist was convinced that ontogenesis completely repeats phylogenesis. That was his mistake. In fact, phylogenesis is formed from a number of ontogeny of representatives of a particular species, and not vice versa. Now the term “biogenetic law” does not apply in the scientific literature.