Neo Darwinism


The neo – Darwinism or modern synthesis as is known, introduced several changes in the way of thinking about evolution and processes evolutionary that occurred throughout history. He proposed a new definition of evolution emphasizing the genetic basis of evolution. It describes the fusion of Mendelian genetics with Darwinian evolution that resulted in a unified theory of evolution. This theory was developed by various evolutionary biologists during the 1930s and 1940s.


What is Neo-Darwinism?

Neo-Darwinism is an approach that was made on the theory of evolution that unifies the foundations on which natural selection was based and the newest discoveries in genetics .

  • What is Neo-Darwinism?
  • History
  • Postulates of Neo-Darwinism
  • Explanation of the theory
  • How it differs from Darwinism
  • Representatives of Neo-Darwinism
  • Examples

What is Neo-Darwinism?

Neo-Darwinism is a theory that consists of the introduction of a series of changes with respect to the way in which evolution and evolutionary processes were presented . He proposed a new concept of evolution referring to it as the changes that occurred in the frequencies of alleles within populations, seeing this process as the genetic basis of evolution.


It is based on the fact that organisms inherit some of their characters from their parents and then transmit them to subsequent generations. Each organism that exists has different characters and for this reason they will also have different survival options and several ways to reproduce , it is for this reason that organisms that have a better adaptation to the environment , will have more offspring and better characters.


Neo-Darwinian theory was developed around the 1930s and 1940s, and was written by Dobzhansky , Simpson , Mayr , Huxley , in the mid-1930s. The authors relied on genetic variability and natural selection , which were provided foundations by the Darwinian theory, but to which some modifications were made mainly due to the new knowledge that they already had on genetics and ecology .

Postulates of Neo-Darwinism

The postulates of the theory of Neo-Darwinism are the following:

  • All the biological diversity that exists comes from a single ancestral life form, from which life evolved along multiple and successive divergent pathways.
  • The evolution can be seen as a process of seed coming from ancestral forms derived forms including some modifications.
  • Evolution is based on mechanical or material factors and processes . Among the mechanisms Darwin accepted the inheritance of acquired characters from Lamark and did not accept any form of vitalism .
  • Darwin’s fundamental mechanism was natural selection, although he also accepted the mechanism of sexual selection, seeing it as a case of natural selection.
  • Evolution is a slow and gradual process, and for this reason selection and gradualism are considered to be fundamental parts of the theory’s features.

Explanation of the theory

In the theory of neo-Darwinism, four different forces of evolution were identified , which contribute to generate or produce the changes that occur in the frequencies of alleles . These forces were  derived random genetic , gene flow , pressure mutation and natural selection, the latter being the most important of all, it makes organisms have the ability to adapt to the environment in which they live.

It is a theory that considers that mutations , the different combinations that occur of genes and natural selection, are the main components that produce the evolution of species, being gene combinations a result of the separation of chromosomes , and of the different permutations that occur during meiosis , therefore, the theory states that mutations are closely related to the genetic variability of the population.

The genetic variability that occurs in species can originate by mere chance , although when it occurs by natural selection, adaptation characteristics can arise ; and chance can cause the end of certain individuals . In this way, when the selection is positive, it will be easier for some of the members of a population to have better and greater chances of survival , reproducing and giving rise to better adapted individuals, in case of being a hereditary factor.

How it differs from Darwinism

Darwinism is considered a nineteenth-century theory that was created simultaneously and independently in which island and tropical ecosystems are studied. Neo-Darwinism is a theory from the last century created by a group of American geneticists who explained the paradigm of evolution. Darwinism ignores population genetics and the existence of different genetic mutations. Neo-Darwinism, on the contrary, considers mutation as the primary source of genetic variability in populations.

Representatives of Neo-Darwinism

The main representatives of the theory of Neo-Darwinism are the following:

  • George John Romanes who first coined the term Neo-Darwinism to explain Alfred Russell Wallace’s theory.
  • Karl Pearson and Walter Raphael.
  • Thomas Hunt Morgan and Ronald Fischer.
  • Wallace and Weismann have been the most influential and important representatives in modern times and who were affiliated with a panselectionist school.


A clear example of neo-Darwinism could be observed for the first time in the birch butterfly and later also in other arthropods ; It is the so-called industrial melanism . This characteristic is defined as the predominant color change as a consequence of the environmental change caused by industrial activity.

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