Understanding Evolution: From Darwin to Neo-Darwinism

Mutation

If mutations are harmful, less fit individuals are eliminated by natural selection.

Synthetic Theory of Evolution

This modern theory of evolution, also called Neo-Darwinism, is currently the most accepted theory to explain the evolutionary processes of any population. Modern scientists argue that all biological organization, starting from the molecular level, has gone through an evolutionary process. Natural selection acting on genetic variation remains the way evolutionary changes manifest.

Development of the Theory of Evolution

In the late nineteenth century, the so-called primitive Neo-Darwinism, which is based on the principle of natural selection as the basis of evolution, found in the German biologist A. Weismann one of its main exponents. This hypothesis supports that the variations on which selection acts are passed according to the theories of heredity enunciated by Mendel, an element that Darwin could not resolve because, in his time, the Austrian monk's ideas were still unknown.

During the twentieth century, from 1930 to 1950, the modern Neo-Darwinian theory, or synthetic theory, was developed. It is called this because it arises from the merger of three different disciplines: genetics, systematics, and paleontology. The creation of this trend is marked by the appearance of three works. Its author, TH Dobzhansky, suggests that genetic variations involved in evolution are essentially minimal and heritable, according to Mendel's theories.

Population and Species

The unified theory of evolution states that living things are descended from a fundamental way of life.

Evolution of Species

To explain the evolutionary process of living beings, we refer to the species. The basic unit of biological classification is the species. A species is a group of individuals that have many characteristics in common and differ from others in one or more aspects. Individuals all come from common ancestors, are related by blood, and can interbreed to produce fertile offspring that resemble their parents.

When comparing the characteristics of living things with actual fossils, we can see that some species have changed; that is, there are differences. Moreover, you can find great similarities between some living things that exist today.

Fixist Theories

Fixism was defended by Plato and Aristotle, who believed that species were the product of a Creator and therefore were fixed, that is, unchanging, and did not evolve or change over time. Some scientists supported this idea, explaining that throughout the geological history of Earth, several catastrophes occurred that wiped out the flora and fauna.

Lamarck's Evolutionary Theory

Lamarck put forward a theory that nature, created by spontaneous generation, formed the first beings, which were subject to constant modification or transformation, according to the use and disuse of organs, so that the current species came from the existing ones.