Lamarckism

The Lamarckism is an evolutionary theory by Jean-Baptiste Lamarck (1744-1829). Although they were important ideas for evolutionary knowledge, Lamarck’s ideas are no longer accepted by the scientific community.

In Lamarckist theory, it was believed that individuals were forced to change by pressure from the environment in which they lived.

Who was Jean-Baptiste de Lamarck?

The naturalist  Jean-Baptiste Lamarck was French and was responsible for the first theories that tried to explain the evolution of living beings.

It was Lamarck who created terms like “biology” and “invertebrates” that are still used today.

He started his scientific life in botany, but later dedicated himself to the study of invertebrates such as mollusks, and it was by observing them that he thought of Lamarckist theory.

In 1809, he published his ideas in French in the book Philosophie zoologique  (“Philosophy zoológica”, in free translation into Portuguese). However, Lamarck died without having his ideas recognized by the scientific community.

He founded the Lamarckist evolutionary theory based on two laws:

  • Law of use and disuse
  • Law of transmission of acquired characters

Law of use and disuse

Lamarck noted that some parts of the individual’s body could develop more if they were used more. Following this same thought, the less used parts would be stunted.

In the classic Lamarckian example of the neck of giraffes, he suggested that giraffes actually had a short neck, but that part of the body had to stretch and become strong to reach the treetops in times of food shortage.

Lamarckismo – Law of use and disuse – Giraffes stretching neck according to Lamarck’s theory

Law of transmission of acquired characters

This law stated that the beneficial characteristics acquired during an individual’s life were passed on to his descendants, who would pass on to all subsequent generations.

Thus, this law was closely linked to the first, since the acquired or stunted characteristics would be passed on from generation to generation.

 Importance of Lamarck’s ideas

Lamarck was an innovative scientist, he was the first to go against creationist or fixist ideas . As in science changes take time to be understood and incorporated, perhaps that is why he died without being recognized.

Although Lamarck was right that fossils were an important record of the evolution of living beings and that there was an adaptation of species to the environment, he erred in saying that these characteristics were transmitted to descendants.

The law of use and disuse can even be applied in some moments, such as gaining muscle mass in an athlete, however, this is not a characteristic acquired in order to make that individual better and more complex, but more adapted to the environment. that lives, and may even become simpler.

Lamarckism and Darwinism

Lamarckism is the evolutionary theory proposed by Lamarck 50 years before Darwinism that was proposed by Charles Darwin.

For Lamarck, the characteristics were developed as they became necessary for the individual and, once acquired, were passed on to the next generations. However, Darwin did not agree with this.

For Darwin, any living being could evolve from an ancestor, improving or losing characteristics, in order to adapt better to the environment. This theory was based on natural selection , where the environment selects characteristics that are more favorable to that individual’s permanence and eliminates the unfavorable ones.

With the knowledge and advances in genetics that followed, Darwinian theory was reformulated and the neo -Darwinian theory was formed , also called the synthetic theory of evolution.

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