Jean-Baptiste Lamarque: contribution to biology. Pros and cons of the Lamarck theory

The first comprehensive theory of evolution was proposed by Jean-Baptiste Lamarque. Contribution to the biology of the scientist was based on the thoughts and principles that already existed in the scientific circles of the time. The most important of these was the idea of scala naturae, as well as the idea that species can change in different environments.

Scala naturae, the "great chain of being," goes back to Aristotle and, probably, to an earlier period. This is a hierarchical classification system, in the lower part of which are the simplest organisms, and at the top - the most complex.

Ideas of species change in the early 19th century were quite common - they did not become a breakthrough in Lamarck. For example, Buffon, his mentor, expressed his own ideas about this, although they were all very vague.

Path to biology

Lamarck went to science in a thorny path, for a long time serving in the army, and four years of studying medicine, before his brother talked him out. He became a disciple of the leading French naturalist Bernard de Jussie, focused on botany, and in 1978 published a three-volume collection of the French flora, which was impressive enough to draw the attention of Buffon, who took him under his wing and provided a place in the French Academy of Sciences and the Royal Botanic Gardens . After the French Revolution, the gardens were transformed into the National Museum of Natural History in 1793, in which Lamarck received the position of professor of invertebrates (despite the fact that this was not his specialty), which he held until his death.

The merit of Jean-Baptiste Lamarck in biology is not limited to the theory of evolution. Many of his achievements are taken for granted - the word "biology" is his invention, like the systematic categories of "vertebrates", "invertebrates", "insects", "shells", "arachnids", "echinoderms", "annelids."

The teachings of Jean-Baptiste Lamarck were presented in three publications. He became interested in evolution, sorting in the Museum of Natural History a collection of fossil and modern mollusks of Bruges, the previous keeper of the exhibits of the department of invertebrates. Lamarck noticed that they are similar, and, putting off their distribution in time, could trace a straight line from ancient samples to the newest. This caused other thoughts, which he set forth in the book of 1801 "Studies of the organization of living bodies."

Jean-Baptiste Lamarck: Contribution to Biology

But the real details of the explanation of the evolutionary process appeared in his main work of 1809, The Philosophy of Zoology. In 1815, the first volume of the textbook "The Natural History of Invertebrates" was published, where Lamarck's ideas were also presented.

The concept of the "great chain" became the cornerstone of Lamarckism. But he went beyond his contemporaries, trying to justify its mechanism, and not take it as self-evident. He suggested that animal life contains a built-in ability, innate quality becomes increasingly complex, which would explain the existence of a natural hierarchical classification. This can be illustrated not as climbing a ladder, but as moving on an escalator.

But then a classic creationist argument arises: if we evolved from monkeys, then why do monkeys still exist? The solution lies in the fact that biogenesis - the formation of a new life - occurs constantly. In other words, there are many escalators (one for each category of life), each of which has its own starting point. People are the oldest organisms, and worms are the newest.

But there is a second problem. Hierarchical classification, such as "worms-fish-reptiles-birds-mammals-primates-man" for, for example, felines does not work. At this level, the hierarchy becomes a meaningless exercise, and here comes the most famous part of Lamarckism: the inheritance of acquired characteristics. This concept is simple.

The giraffe lives in a savannah with tall trees. This induces a "need" in the giraffe, and it changes its behavior to reach higher branches. According to Lamarck, this additional use of the neck will lead to its growth due to the increased flow of "vital fluid". The new condition of the neck is an acquired characteristic, and it can be transmitted to the offspring, which is why it is about inheriting the acquired characteristics.

The converse is also true: if the organ is not used, then the fluid flows through it less, and it atrophies. For example, this explains why the cave dwellers have no eyes.

Inheritance of acquired characteristics

Another example is the membrane between the fingers of many waterfowl animals, such as frogs, sea turtles, otters and beavers. To swim, the animals need to push out water, which is due to the membranes, resulting in them getting more "life fluid", as Jean-Baptiste Lamarck believed.

Contribution to the biology of the scientist includes a basic concept of the inheritance of acquired characteristics. This did not become a physiological discovery ("life fluid" was never found). It was a purely naturalistic and mechanistic view, which at that time proved revolutionary. There was no need for God as the leader of evolution. The concept also went against the notion that organisms can only be changed in a certain way.

Thus, there are two fundamental principles of Lamarckism. The first of these is the idea of natural, linear progress on the scale of complexity. However, the path to excellence is extremely tortuous: organisms adapt to local conditions, which led to a variety of forms, even at the same level of complexity.

Knowing what Lamarckism is, you can critically evaluate the pros and cons of Jean-Baptiste Lamarck as a researcher from a modern point of view.

Any philosopher of science will say that setting the right tasks and correctly asking questions is half the scientific research. It was in this respect that Jean-Baptiste Lamarck distinguished himself: his contribution to science was that he understood four main problems of the natural history of the time:

1. Why do fossil forms differ from those that have reached us?
2. Why are some organisms more complex than others?
3. Why is there such a variety?
4. Why are organisms well adapted to their environment?

The disadvantages of Jean-Baptiste Lamarck are that he failed in providing any correct explanation, although not through his own fault. Anyone in his place would stop on such a set of ideas, rather than on natural selection or mutations.

Jean-Baptiste Lamarck: The Mistakes of Theory

Lamarck argued that the fossil forms are different, because they, as they climbed the escalator of evolution, were replaced by more complex ones. Now we know that fossil forms belong to different parts of phylogeny, and, therefore, are different.

There is no such thing as a scale of complexity. Complex forms arise in individual taxa as a result of their unique circumstances. The most typical example of complexity - multicellularity - is unique and is not the result of a widespread tendency.

Diversity is not a product of constant biogenesis. Everything points to the only source of life. Variety is the result of speciation.

There is no such thing as a "vital fluid". Organisms are adapted to their environment, as they have passed through the inexorable millstones of natural selection.

In natural selection, as it is understood today, the entire population of giraffes with variable neck size is taken into account. Those with a longer neck can reach higher branches of trees, and thus have access to more food. This gives them more energy and an advantage in reproduction, which in the long run will lead to the production of more offspring. If we assume the genetic basis of the length of the neck, then, most likely, a longer progeny will be born, which over many generations will supplant the short-necked.

In the Lamarckian giraffe it is necessary to reach higher trees, and therefore its neck lengthens, and this is passed on to the offspring.

Now the fallacy of the second core of the theory, created by Jean-Baptiste Lamarque, is obvious.

Useful mutations are an exception, not a rule

The scientist's contribution - the idea of progress on a scale of complexity - is also not confirmed even at the molecular level. Motu Kimura and Tomoko Ohta, the founders of the currently dominant neutral and near neutral theories of molecular evolution, have shown that mutations are overwhelmingly neutral - they have no effect on the adaptability of the organism. The second theory states that many of the neutral mutations will have an effect too small to be truly noticeable. The remaining mutations are harmful, and only a small number of them are actually useful.

If there was a predetermined line of movement towards perfection, then all mutations would be beneficial, but this is not supported by evidence.

Thus, not a single Lamarck concept has been confirmed.

Panacea for theology

The idea of "vital fluids" did not spread, so Lamarckism and evolution were challenged until Darwin's "Origin of Species" conquered the world. Darwin showed the reality of evolution. Nevertheless, he failed to convince everyone of natural selection.

The idea of inherited acquired features, which even Darwin used, became a synonym for Lamarckism, as well as a whole series of theories that arose in opposition to natural selection. In scientific circles, neo-Lamarckism as a whole defeated Darwin's theory. Theology, which half a century ago vehemently opposed Lamarckism, now fully accepted it only because the action of the "vital fluid" can easily be attributed to the creative deity who intelligently designs adaptation to the environment, which turned out to be more convenient than the "chance" of natural selection.

In 1900, neolamarcism and selectionism were crushed by the rediscovery of genetics and the emergence of a mutational theory.

Militant Lamarckism of Lysenko

In Russia, one of the black chapters in the history of biology and science as a whole unfolded: Lysenkoism. Trofim Lysenko was a mediocre scientist with enormous political influence, which he used to climb to the top of Soviet biological science, and by 1930 became the head of the Academy of Agricultural Sciences. Here he dictated his own idea of evolution by dictatorial methods - the "Michurinsky method", a kind of Neolamarcism, and persecuted geneticists who disagreed with this position. Michurinism became a "new biology", which was well suited for collectivization, because it mixed politics with pseudoscience. Lysenkoism was officially ended in 1964.

Epigenetics - a new Lamarckism?

Thus, with the theory alternative to natural selection, the question was closed. However, in 2013, Jean-Baptiste Lamarck, whose contribution to biology - Lamarckism - turned out to be untenable, got a chance for rehabilitation. Then a work was published according to which mice, trained to be afraid of the smell of acetophenone, transferred this ability by inheritance. The New Scientist magazine called the work a confirmation of the inheritance of the acquired features of Lamarck. True, the effect is based on epigenetics - changing the work of genes, rather than genes themselves, which does not contradict natural selection. Thus, the evolutionary doctrine of Jean-Baptiste Lamarck can once again be rehabilitated.