Lamarck’s theory and evolution of species

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

the Lamarck’s theory this is one of the most famous attempts to come up with an idea of ​​the evolution of species in which there is no divine intelligence to direct the process.

Who was Lamarck?

The person who proposed what we know today as Lamarck’s theory was Jean-Baptiste de Lamarck, Was a French naturalist born in 1744. In her day, the study of living things was a completely different discipline from what is today biology, and that is why she had ideas about how natural processes work in which the divine intervened, which would be scandalous by current scientific standards.

Lamarck made biology largely independent of religion propose a theory of evolution in which the intelligences of the 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 offered an explanation of how different life forms could have appeared without the need for one or more gods.

His idea was that although the origin of all life forms could be created spontaneously (presumably by the direct work of God), but after that evolution occurs as the product of a process. Mechanical fruit of the physical and chemical properties of the material with which organisms are formed and their environment.

The basic idea of ​​Lamarck’s theory was: the environment is changing, lifestyles are struggling to constantly adapt to the new requirements of their habitatThese efforts change their body physically, and these physical changes are inherited by the offspring. In other words, the evolution proposed by Lamarck’s theory was a process based on a concept called inheritance of acquired characteristics: parents pass on to their children the traits they acquire from the way 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 surroundings become drier and drier, so the grass and shrubs begin to become scarce and have to resort to feeding on the leaves of trees more often. This makes neck stretching one of the defining habits of daily life for some members of their species.

Thus, according to Lamarck’s theory, pseudo-antelopes that don’t struggle to access tree leaves by stretching their necks tend to die leaving little or no offspring, while those who stretch the neck survive not only because the neck is elongated, but this physical characteristic (the longer neck) is passed down to their inheritance.

This way, over time and generations, a way of life that did not exist before appears: the giraffe.

From simplicity to complexity

If we move from the foreground to the description of the process by which one generation transmits its acquired characteristics to the next, we will see that the explanation by which Lamarck’s theory seeks 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 way of life which, generation after generation, gave way to more complex organisms. These late species bear traces of the adaptation efforts of their ancestorsThus, the ways in which they might adapt to new situations are more diverse and give way to a greater variety of life forms.

What’s wrong with Lamarck’s theory?

If Lamarck’s theory is considered an outdated model, it is, in the first place, because we know today that individuals have a limited margin of possibility when it comes to modifying their body with its use. For example, necks don’t lengthen just by stretching, and the same goes for legs, arms, etc.

In other words, the fact of using specific strategies and body parts does not require them to adapt their morphology to improve the performance of this function, with a few exceptions.

The second reason Lamarckism fails is because of its assumptions about the inheritance of acquired abilities. Physical changes that depend on the use of certain organs, such as the degree of muscle building in the arms, they are not transmitted to the offspringAutomatically, because what we are doing does not alter the DNA of germ cells the genes are passed on during reproduction.

Although some life forms have been shown to pass their genetic codes to others through a process known as horizontal gene transfer, this form of genetic code modification is not the same as 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 that this is the function of has recently been discovered. restart the epigenome of developing life forms in their zygote phaseThat is, make sure that no acquired changes can be inherited by the offspring.

The differences with Darwin

Charles Darwin also attempted 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 how the pressures and demands of the environment and the lifestyles that coexist with each other cause that, in the long run, some traits are passed to offspring more frequently than others, What over time would make so that a good part of the individuals of the species, if not almost all, end up possessing this characteristic.

Thus, the gradual accumulation of these changes would mean that over time different species would be created.

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 despised until the time of his death. Despite this today Lamarck is widely recognized and admired not because his theory was correct and served to explain the process of evolution, since Lamarck’s theory has become obsolete, but for two different reasons.

The first is that the way that Lamarck conceived evolution can be interpreted as an intermediate stage between classical creationism that all species were created directly by God and remain the same across generations, and Darwin’s theory. , 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 this naturalist had to face in conceiving 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 for this you need to analyze very specific aspects of life forms in detail and build with it a very abstract theory that explains the type of natural law behind all this kind of situation. change.

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