Biogenetic Law: Ontogeny, Phylogeny, Cognitive Development

Ernest Haeckel, the famous German zoologist, philosopher and the artist reiterated the idea of Biogenetic law in the year 1860s after going through “The Theory of Evolution” by Charles Darwin. This law is basically the theory which states the various phases of an animal embryo which undergone the developmental stages & are the replay of the sequences of the past ancestral forms of their species. It clearly portrays the adult form of an ancestor post-evolution. The law carefully states the analysis of the different phases of an embryo that is responsible to fuel the entire process of diversification of life and also studies of history. The theory confirms that all species have evolution from some common ancestor.

Keyterms: Biogenetic law, Evolution, Embryo, Fuel, phylogeny, evolution stage, developmental stage, ontogeny

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What do you understand by Biogenetic Law?

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Biogenetic law can be explained as a theory of evolution and development proposed by a famous German Zoologist, Ernest Haeckel in 1860s. It is commonly stated as ontogeny reiterating phylogeny, the theory in which developments takes place in a chronological order when an embryo goes through several developmental stages from the past evolution forms to the current evolution stage.

Haeckel though praises Darwin’s concept of the ‘process of evolution’ but he disagreed with his concepts about embryology & evolution. Haeckel stated that it is a progressed development as the embryos have diverged more and more from one to another. Whereas, Darwin stated that the evolution was not progressive.

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Three Assumptions of Biogenetic Law

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Haeckel stated that, Biogenetic law is dependent on three assumptions.

• First, ‘the Law of Correspondence’, according to which each stage of the development within the higher animals corresponds to the adults stages of lower animals. Example: Humans to the fish (gill sits in the early human embryos have correspondence to the gill slits in adult fish)
• Secondly he states that the end of the process of normal development must include phylogenesis that must occur with the addition of new characteristics. At first, the embryos look similar in appearance but with further development the constraints disappears which results in subsequent evolution.
• Third, the ‘Principle of Truncation’ in which he explains that the continuous addition of new characters will add to the end of normal ontogeny. Eventually, the length of development of embryo will be much longer of the living organisms than gestation periods of extent species, which will result faster stages of development in higher organisms than in the lower organisms.

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Biogenetic Law: Ontogeny

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The Origination and the process of evolution of an entity from the stage of egg-fertilization to the stage of formation of an individual is known as Ontogeny. It also can be referred to the history of development from an entity within its lifetime. Ontogeny is very useful in various fields of studies including developmental biology, developmental cognitive neuroscience, developmental psychology and developmental psychobiology. It is also used in anthropology because “the process through which each of us embodies the history of our own making”.

Various aspects of Ontogeny include tissue growth, morphogenesis, the development of form & cellular differentiation.

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Biogenetic Law: Phylogeny

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The evolutionary history of a species is what we refer to as phylogeny. Phylogeny or Phylogenetics is the broad study of the evolutionary relationship in the biological entities- often individuals or species or genes. Major elements responsible for Phylogeny are briefed in the diagram given below:

Phylogenetics is very important as it develops our understanding of the evolution of species, genes, genomes and molecular sequences. It also helps us to predict how these sequences will change in future. Phylogeny is extremely useful in numerous applications like:

• Classification – more accurate descriptions of relatedness are provided. Phylogenesis also helps in the Linnaean classification of any new species.
• Identifying the origin of pathogens- the new species of pathogens which are related to and are subsequently the source of transmission which can further be helpful for public health policy.
• Conservation – conservation policies are there in cases of tough decisions about which species to prevent from getting extinct.
• Forensics – Assessment of DNA evidence are presented in court for the situations like crime, food contamination, father of a child is unknown and etc.
• Bioinformatics & computing – Various Algorithms are developed for the use of phylogenetics to develop software in other fields.

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Biogenetic Law: Applications

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Bio genetic law is used in some fields like:

• Field of Art – to create and recast the history of art
• Cognitive Development – phases like child’s cognitive development & biological evolution are considered similar to the development in evolutionary stages that are proposed in history.

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Things to Remember

• In 1860s, Ernest Haeckel proposed the theory of Biogenetic Law
• Haeckel’s biogenetic Law is based upon Darwin’s “Theory of Evolution”.
• In Biogenetic law, Ontogeny recapitulates Phylogeny which is called the recapitulation theory
• The recapitulation theory or law is used in various fields like Field of Art and Cognitive Development.
• Due to not much availability of Haeckel’s observations, his theory of biogenetic law was abandoned in early twentieth century

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