LAMARCK'S THEORY OF TRANSFORMISM (WITH EXAMPLES) - BIOLOGY - 2024

The theory of transformism of Lamarck is the set of principles and knowledge formulated by Jean-Baptiste Pierre Antoine de Monet Chevalier de Lamarck in 1802, to explain the evolution of life.

Lamarck was a French naturalist who lived between 1744 and 1829. His work as a naturalist consisted of important research on natural sciences and history that led him to formulate the first theory of biological evolution to find answers about living things. He also founded the paleontology of invertebrates for the study of the past of fossils.

Lamarck's Theory, also called Lamarckism, states that the great variety of organisms is not, as was believed until then, “always the same” but that living beings begin as very simple forms that change over time.

This means that they evolve or transform to adapt to the environment in which they live. As changes occur in the physical environment, living beings acquire new needs that generate transferable modifications from one generation to another.

Basis of your research

- Living organisms are organized bodies produced on Earth by nature over a large amount of time.

- The simplest forms of life constantly arise.

- Life, whether animal or vegetable, in its perpetual evolution, gradually develops more specialized and diversified organs.

- Each organism has the reproductive and regenerative capacity of living beings.

- Over time, conditions caused by changes in the Earth and assimilation of various maintenance habits of organisms give rise to the diversity of life.

- The product of this diversity are the "species" that materialize the changes in the organization of living bodies. (O'Neil, 2013).

Lamarck argued that, observing nature, the existence of many different forms and habits among animals is undeniable. This diversity allows to consider innumerable conditions in which beings of each group of organisms (or race) have responded to the changes to satisfy their needs.

Laws

With these premises he formulated two basic laws:

- In every animal, the frequent use of its organs strengthens its functions while the constant disuse of the same weakens its power until they disappear.

- Genetics is responsible for perpetuating, through future generations, the modifications that organized bodies have had to undergo to meet their needs in the face of changes in their environment.

Rationale for your research

Circumstances create needs, they create habits, habits produce modifications due to the use or not of certain organs or functions, and genetics is in charge of perpetuating these modifications.

The qualities of each generation come from their own inner effort and their new abilities are passed down to their descendants.

Examples illustrating the principles of this theory

Example 1

Originally, giraffes had necks like that of horses. They usually live in areas where drought is frequent, therefore, the need to acquire the water reserves of the plants created the habit of feeding on the tender shoots of the treetops.

Over time, many generations of giraffes needed to meet this need, which caused the length of their neck to change.

Longer-necked giraffes passed on this trait to their descendants, and each generation was born with a longer neck than their parents. This process continued until the neck of the giraffes reached the current length.

Example 2

Due to prolonged dry spells, low-level rivers do not offer the bulky elephant the ease of taking a bath. Nor is it possible for this huge animal to bend over to reach the water from a small well with its mouth. For this reason, successive generations developed a long trunk to be able to drink and refresh their body.

Example 3

Iguanas are usually slow and feed on insects that are very agile, moved by the need to feed, successive generations developed the independent use of each of their eyes to capture their food faster.

Example 4

The defense mechanism of many animals to avoid being eaten is another example of evolution. In their struggle to survive, they develop physical changes that scare off their predators. Such is the case of the puffer fish that, in the presence of the enemy, inflates its body. Inherited animal habits, like this one, are infinite in nature.

Example 5

The birds adapt, generation after generation, the size of their beaks and legs to better manipulate the type of branches they need to build their nests according to the habitat that corresponds to them. (www.examplesof.net, 2013).

Zoological philosophy

In 1809, Lamarck published a book called Zoological Philosophy that was well known in France and England, but its principles were not taken into account in his day.

His approach had opponents, such as August Weismann (a German evolutionary theorist), who did an experiment to try to discard the principle of Lamarckism.

He cut off the tails of successive generations of mice to show that their offspring were not born without tails. Indeed, the new generations were born with the tail inherited from their parents. This was a misinterpretation of Lamarck's theory.

In the first place, the action of cutting the tail was unnatural (it was not produced by nature). Second, for mice in captivity, it was a circumstance that did not create a need, did not create habits in those mice to maintain life. Therefore, it did not produce modifications in the genetics that were transmitted, in time, to their descendants. (Beale, 2016).

Despite its detractors, even today, a part of the members of the scientific community consider important the study in detail of Lamarck's theory of biological evolution.

The basis of Lamarckism is usually summed up as "the inheritance of acquired characters." This means that the species are descended from each other and that the new generations are gradually more complex and better adapted to the environment than the previous ones. (Richard W. Burkhardt, 2013).

References

1. Beale, GH (04-11-2016). Retrieved from global.britannica.com.
2. en.wikipedia.org. (last modified on 12 March 2017, at 00:17). Lamarckism. Retrieved from en.wikipedia.org.
3. en.wikipedia.org. (last modified on 5 April 2017, at 03:11.). Jean-Baptiste_Lamarck. Obtained from.wikipedia.org.
4. es.wikipedia.org. (Last modified Apr 4, 2017 at 10:46 am). Obtained from es.wikipedia.org.
5. O'Neil, DD (2013). Retrieved from anthro.palomar.edu.
6. Richard W. Burkhardt, J. (08 of 2013). Retrieved from dencbi.nlm.nih.gov.