Lamarck’s Theory and the evolution of species

Does God exist or is everything a product of the evolution of species? Lamarck provides his theory.

For centuries, the question of how the different forms of life have arisen has been a question that has fascinated mankind. Myths and legends have been created around this question, but also more complete theories have been developed. more complete and systematic theories have also been developed..

The Lamarckian theory is one of the most famous attempts to propose an idea of the evolution of species in which there is no divine intelligence directing the process.

Who was Lamarck?

The person who proposed what we know today as Lamarck's theory was Jean-Baptiste de LamarckHe was a French naturalist born in 1744. In his time, the study of living beings was a totally different discipline from what biology is today, and that is why it held ideas about the functioning of natural processes in which the divine intervened, something that would be scandalous by today's scientific standards.

Lamarck made biology largely independent of religion by proposing a theory of evolution in which the divine intervened. by proposing a theory of evolution in which intelligences from beyond had no role..

What did Lamarckism consist of?

Before the English naturalist Charles Darwin proposed the theory of evolution that would forever change the world of biology, Lamarck's theory already proposed an explanation of how the different forms of life had been able to appear without the need to resort to one or more gods.

His idea was that although the origin of all forms of life could be created spontaneously (presumably by the direct work of God) but that, after this, evolution was produced as a product of a mechanical process resulting from the physical and chemical properties of the matter from which the organisms and their environment are formed.

The basic idea of Lamarck's theory was the following: the environment changes, life forms struggle to adapt continuously to the new demands of their habitat, and these efforts modify their physical bodies.These efforts modify their bodies physically, and these physical changes are inherited by their offspring. In other words, the evolution proposed by Lamarck's theory was a process that is based on a concept called inheritance of acquired characteristicsThe parents transmit to the offspring the traits they acquire from how they relate to the environment.

Let's see how this hypothetical process worked using the most famous example of Lamarck's theory: the case of giraffes stretching their necks.

The example of giraffes and Lamarck

At first, an antelope-like animal sees its environment becoming drier and drier, so that grass and shrubs become increasingly scarce and it needs to resort to feeding on tree leaves more frequently. This causes neck stretching to become one of the defining habits of everyday life for some members of their species.

Thus, according to Lamarck's theory, pseudo-antelopes that do not struggle to reach the leaves of trees by stretching their necks tend to die. leaving few or no offspring, while those that stretch their necks not only survive because their necks are longer, but this physical characteristic (longer neck) is passed on to their offspring.

In this way, with the passage of time and generations, a form of life appears that did not exist before: the giraffe..

From simplicity to complexity

If we move from the foreground of describing the process by which one generation passes on its acquired characteristics to the next, we see that the explanation by which Lamarck's theory attempts to account for the diversity of species is quite similar to the ideas of Charles Darwin.

Lamarck believed that the origin of species was embodied in a very simple form of life that generation after generation gave way to more complex organisms. These late species carry the traces of the adaptive efforts of their ancestors.The forms in which they could adapt to the new situations are more diverse and give way to a greater variety of life forms.

Where does Lamarck's theory fail?

If Lamarck's theory is considered an outdated model, it is, in the first place, because today it is known that individuals have a limited margin of possibilities when it comes to modifying their bodies through their use. For example, necks do not lengthen by the simple fact of stretching them, and the same happens with legs, arms, etc.

In other words, the fact of using certain strategies and body parts a lot does not make them adapt their morphology to improve the fulfillment of this function, with a few exceptions.

The second reason why Lamarckism fails is because of its assumptions about the inheritance of acquired capacities. Those physical modifications that do depend on the use of certain organs, such as, for example, the degree of arm musculation, are not transmitted to the offspringThe fact is that what we do does not modify the DNA of the germ cells whose genes are transmitted during reproduction.

Although it has been proven that some forms of life transmit their genetic codes to others by a process known as horizontal gene transfer, this form of modification of the genetic code is not the same as that described in Lamarck's theory (among other things because in his time the existence of genes was not known).

In addition, a type of gene has recently been discovered whose function is to reset the epigenome of life forms that are being created in their zygote stagethat is, to ensure that there are no acquired changes that can be inherited by the offspring.

Differences with Darwin

Charles Darwin also tried to explain the mechanisms of Biological evolution, but unlike Lamarck he did not limit himself to placing the inheritance of acquired characters at the center of this process.

Instead, he theorized about the way in which the pressures and demands of the environment and of coexisting life forms eventually cause certain traits to be passed on to offspring, certain traits are passed on to offspring with greater frequency than others.In this way, the progressive accumulation of such traits over time would lead to a good part of the individuals of the species, or even almost all of them, eventually possessing that characteristic.

Thus, the progressive accumulation of these changes would lead to the creation of different species over time.

The merits of Lamarckism

The fact that this naturalist rejected the idea that miracles play an important role in the creation of all species caused Lamarck's theory of evolution to be ignored or belittled until the time of his death. In spite of this today Lamarck is widely recognized and admired, not because his theory was correct and not because his theory was correct and served to explain the process of evolution, since Lamarck's theory has become obsolete, but for two distinct reasons.

The first is that the way in which Lamarck conceived evolution can be interpreted as an intermediate step between classical creationism, according to which all species have been created directly by God and remain the same through the generations, and Darwin's theory, the basis of the theory of evolution, which is the current foundation of the science of biology.

The second is simply the recognition of the difficulties that this naturalist had to face in devising and defending the Lamarckian theory of evolution in its historical context at a time when the fossil record of life forms was scarce and chaotically classified. Studying something as complex as biological evolution is not at all easy, because it requires a detailed analysis of very specific aspects of life forms and the construction of a highly abstract theory that explains the kind of natural law behind all these kinds of changes.