In details


Lamarck: theory to explain the evolution of species

What is (definition)

Lamarckism is a theory developed by the French biologist Jean-Baptiste Lamarck in the early nineteenth century. This theory aims to explain the evolution of species. Lamarck published his theory in the year 1809 in the book “Zoological Philosophy”, which was of great importance to the biological sciences, as it served as the basis for Charles Darwin's work.

The two postulates of Lamarckism:

Through these two postulates, Lamarck intended to explain the evolution of all species from the beginning of life on planet Earth.

Law of use and disuse

According to Lamarck, an organ in the human body develops more and more as it is used more. On the other hand, by atrophying and even disappearing if little used.

Law of hereditary transmission of acquired characters

- This law complements the first. According to Lamarck, the characteristics acquired by a species, due to the use and disuse of the organs, are transmitted from generation to generation, that is, inherited. Changes in the environment induce changes in the organs of animals.

Classic example of giraffe neck

The example of the giraffe's neck is one of the most illustrative of Lamarck's theory. In the past, giraffes had a short neck. With food shortages at certain times, a change in behavior by these animals was necessary to ensure survival. In order to reach the tops of the trees and eat the leaves, the giraffes craned their necks. With each generation of giraffes, they were born with a slightly larger neck.

Lamarckism and Darwinism

Lamarck was right to say that organs can develop with use and atrophy with disuse. However, the theory that these traits are transmitted inherited proved to be incorrect by science, especially the theory of species evolution of the English naturalist Charles Darwin.

Darwin was able to demonstrate from the theory of natural selection that the strongest and most fit individuals of a species tend to reach adulthood more easily and generate new individuals with these developmental characteristics. Those weaker or with poor developmental characteristics tend to disappear over time. In this way, the fittest of the species survive, conveying their characters through heredity.