Biogenetic Law: Definition, Meaning, Ontogeny, Phylogeny, Applications

Biogenetic Law, also known as the theory of recapitulation, was introduced by German scientist Ernst Harckel after reading Darwin’s Theory of Natural Selection. It suggests that the development of an organism from fertilization to maturity retraces the evolutionary history of its species. This means that an animal embryo passes through various stages during its development that resembles the adult forms of its ancestors. This idea is also known as “ontogeny recapitulates phylogeny”, indicating a link between embryology and evolutionary biology.

This Story also Contains

1. Ontogeny
2. Phylogeny
3. Three Assumptions of Biogenetic Law
4. Applications Of Biogenetic Law
5. MCQs on Biogenetic Laws

Biogenetic law was influenced by Meckel-Serres law which was given by Etienne Serres based on the work of Johann Friedrich Meckel. Though science has advanced and partially rejected the theory, the concept still holds historical significance. It highlights how embryo development can show in evolutionary patterns. This has encouraged scientists to study embryos to understand the history of the species. According to the legislation, a detailed examination of an embryo's developmental stages stimulates the variety of life and historical research.

Ontogeny

Ontogeny is the beginning and development of an entity. It starts with fertilization and ends with the development of an adult. It suggests the path an organism followed during its lifespan. As individuals develop and species change, developmental processes can affect the following evolutionary stages. Ontogeny is used to describe how different cell types develop within an organism. It is important to understand ontogeny as it helps scientists trace genetic interactions, identify developmental abnormalities, and relate embryonic stages to evolutionary history.

Phylogeny

Phylogeny refers to the evolutionary history and relationships among species. It shows how organisms are related through common ancestors. These relationships are often represented using a phylogenetic tree, a diagram that shows connections based on physical and genetic similarity. In simple words, it is similar to a family tree. Closely related species show more similarities than distant ones.

Studying phylogeny is important to understand how species, genes, and traits have evolved over time. It helps scientists trace the origin of organisms and predict how they might change in the future. Phylogeny is very helpful and has application in various fields:

• Classification: Helps in classifying organisms more accurately by showing how closely they are related.

• Finding the origin of pathogens: Helps to trace the origin and spread of new diseases and viruses, useful for developing public health policies.

• Conservation: Helps in identifying the biodiversity that can go extinct based on their evolutionary uniqueness.

• Forensics: DNA analysis based on phylogenetic data can be used in cases involving criminal activity, tainted food, unidentified fathers of children, etc.

• Bioinformatics & computing: Used to create software and algorithms to analyze biological data using evolutionary relationships.

Three Assumptions of Biogenetic Law

Biogenetic Law, proposed by Haeckel, is based on how embryonic development reflects in evolutionary history. It helps explain why embryos of different species look similar in the early stages of development and how new traits appear as development progresses. Haeckel made the following assumptions:

• Law of Correspondence: It states that early developmental stages in higher animals resemble the adult stages in lower species. Example: Human embryos show gill slits in early development, similar to adult fish. This shows common ancestry.

• New Traits in Later Stages: Haeckel believed that as embryos grow, they pass through stages similar to other organisms and then develop new features that are unique to their own species. All embryos initially have a similar appearance, but differences appear as they grow and develop.

• Principle of Truncation: According to this, the development of higher animals becomes faster over time. Some early stages are short and more new traits are added. This means that although higher animals have longer gestation periods, the early stages appear more quickly compared to lower organisms.

Applications Of Biogenetic Law

Although modern science has revised many aspects of Haekel’s theory, these applications continue to provide perspectives in several fields such as science as well as humanities. It helps scientists trace changes during evolution and understand how traits are evolved. It also influences interdisciplinary studies connecting biology with art, psychology, and education. Here is list of applications of biogenetic law:

1. Evolutionary Biology: It provides a framework for studying how traits evolve by observing embryonic development.

2. Field of Art: In art history, the biogenetic principle has been used to trace the development of artistic styles.

3. Cognitive Development: Some researches related the development of a child’s mental and emotional growth to the evolutionary stages of human development.

Paleontology and Fossil Interpretation: It helps to interpret the fossil records by linking developmental stages in modern organisms and population to features of ancient species.

MCQs on Biogenetic Laws

Q1. The biogenetic law states that:

1. Ontogeny repeats phylogeny

2. Phylogeny repeats ontogeny

3. Both ontogeny and phylogeny are unrelated

4. Ontogeny is independent of phylogeny

Answer: 1) Ontogeny repeats phylogeny

Explanation:

The biogenetic law, proposed by Ernst Haeckel, suggests that ontogeny (the development of an individual organism) goes through stages that resemble the evolutionary history (phylogeny) of its species. For example, during embryonic development, humans exhibit features like gill slits, which are found in ancestral aquatic organisms like fish. Hence, the statement "Ontogeny repeats phylogeny" correctly summarizes the concept.

Hence the correct answer is option 1) Ontogeny repeats phylogeny.

Q2. In the context of the biogenetic law, ontogeny refers to:

1. The evolutionary history of a species

2. The development of an individual organism

3. The study of fossils

4. The process of natural selection

Answer: 2) The development of an individual organism

Explanation:

Ontogeny is the biological term for the entire sequence of events in the development of an organism, from fertilization of the egg to its mature form. In biogenetic law, ontogeny is compared to phylogeny (the evolutionary development of the species), implying that individual development mirrors ancestral evolution.

Hence the correct answer is option 2) The development of an individual organism.

Also Read:

• MCQs on Evolution

• Adaptive Radiation

• Genetic Drift