History of the transformism

The transformism is a biological theory whose history goes up at the time where Jean-Baptiste de Lamarck stated his famous theory on the evolution of the species.

It indicates today indifferently any theory implying a variation (or transformation) species during the geological history. One can in that oppose it to the Fixisme, and thus to the Créationnisme and his various alternatives (theory of punctuated creations, for example)

The Revolution transformist in France (1800 - 1882)

In addition to the scientific problems of the great age of the ground causing several inevitable conflicts with the literal interpretation of the Bible, another great irresolute problems at that time were the question of the Fossile S and the extinction of forms of life. Indeed, with the intensification of the studies, it had become obvious that many species Fossile S were different from the species alive from today. But the problems become inevitable when one discovered at the 18th century of the Mammifère S fossilized, such as the Mastodonte S in North America and the Mammouth S in Siberia.

For several natural theologists deists the extinctions were inconceivable, because the concept of plenitude did not agree with these last, God having created all the possible alive species would not allow that one of them disappears. For the other naturalists mainly theists, the problems of the extinctions were not clearer, since God could not intervene on ground and modify or create anything. It had then is to postulate a law established as of the creation of the world explaining the constant extinction of old species and appearance of new species during geological time or quite simply to deny these last. One then tried several assumptions during XVIIIe and of the XIXe century.

A very popular explanation wanted that the extinctions of species were caused by the Flood or any catastrophe. However, the fact that several disappeared species were watery discredited this theory. Despite everything it is in a similar way, the Catastrophisme, that several naturalists, such as Georges Cuvier (1769-1832) or Louis Agassiz (1807-1873), tried to explain the phenomenon of the extinctions. One second explanation was that the presumedly extinct species could survive elsewhere in some still unexplored area of the sphere. Finally, some explained the extinctions by saying that they had been the work of the man especially in the case of the mammoth and the mastodon. It should have been waited until Jean-Baptiste de Lamarck (1744-1829) states his theory transformist so that a new assumption comes to fall under the history. Indeed, Lamarck was him also concerned with the problem of the extinctions. And it is by introducing the geological data and the factor time, due to the great age of the ground, which it encircled the fault of natural theology. According to him, one could not maintain any more the idea according to which the organizations were created perfectly adapted to their environment, since the ground had continuously changed. Consequently, the species, having to be in balance with their environment to survive, were to also change, because the adaptations, under such conditions of geological changes, could be maintained only if the organizations adjusted themselves constantly with the circumstances, i.e. evolved/moved. It thus rejected the concept of preadaptation for an adaptation by transmission of the assets. By the fact even, the extinctions became a pseudo problem since finally the fossilized species that one believed extinct still existed, they had quite simply changed in such proportions that one did not recognize them any more, except when one could follow in an uninterrupted series of fossils an evolution proceeding in an extremely slow way.

And it is precisely in this manner that several historians explain the reversal of positions that Lamarck carries out between its Speech opening for its annual course on the invertebrates in 1799 and that of 1800. Indeed, Lamarck, then essentialist, adopted positions creationists in its work during about thirty year before radically modifying, around 55 years, its vision of the world, and with becoming the first enthusiastic defender of the transformism in France, theory at that time radically revolutionary and with counter-current. What could explain the reversal of paradigm of Lamarck in 1800?

According to Ernst Mayr (1904-2005), the fact that at the end of the years 1790, Lamarck agreed to take in hand the collection of invertebrates of the Muséum of Paris, with died of his/her friend Jean-Guillaume Bruguiere (1750-1798), and that this impressive collection contained at the same time recent molluscs and others fossilized. At the time of these studies on this collection, Lamarck realized that several current species of moulds and molluscs had astonishing resemblances to certain fossil species considered extinct.

Indeed, it was often possible to arrange the fossils of the old and recent layers of the tertiary sector according to a time series ending in a current species. If the material were complete, it was even possible to virtually establish phyletic series without rupture. The conclusion became inevitable that many phyletic series had undergone a slow and gradual change during time.

Thus, for Lamarck, the evolutionary change was thus the only logical answer to the problem of the extinctions. It had thus the merit to be the first to work out a systematic scientific theory of the evolution of the life which formulates, by postulating the origin of life on ground following a spontaneous generation, a gradual progression of the organizations simplest towards most complex or organized - that is to say the man in the vision of Lamarck - to explain the transformations of the living beings. Thus, the linear image of the Large chain of the Beings, for first once, is replaced by those of a buissonnant tree, because Lamarck postulates two principal evolutionary trunks, one for the vegetable kingdom, the other for the animal kingdom. However, the process of connection for Lamarck is a process of adjustment and not, like in the case of Charles Darwin (1809-1882) and of the later evolutionists, a process able with him to only produce diversity at the species.

Lamarck considered that one needed a theory in order to explain two well-known phenomena in Biologie. The first was that the animals show a graduated series of improvement, energy of the simplest animals until those equipped with the organization most complex. The other phenomenon which it tried to explain was the astonishing diversity of the organizations. In its zoological Philosophie , that it published in 1809, Lamarck distinguishes extremely well what separates its design from that of creationism and the Créationnisme. He thus formulates two laws which, actually, are only two supposed intuitive assumptions to give an account of the fundamental mechanism of the evolutionary process.

Law Lamarckienne

The first law was the capacity of the being alive, following the more frequent and constant use of an unspecified body, to develop little by little this body according to employment that one holds for him, and on the other hand, to gradually deteriorate faculties of a body if this last is not used. Thus while simplifying, the function creates the body. It is interesting to note that this law of use and disuse of a body was a usually allowed observation at the time of Lamarck, and that it did nothing but exaggerate it. In its second law, Lamarck postulates its famous thesis of the Hérédité of the assets which consists of the possibility of transmitting to our descent the organic changes or morphological assets during our life in connection with the first law. Lamarck used, to support its theory of the evolution, of the examples now famous, such as the lengthening of the neck of the giraffe due to a use constant or the atrophy of the eyes of the moles under the influence of the medium.

Following the development of its theory, Lamarck, in addition to solving the problem of the extinctions, foot-note which its transformist explanation was logical for another reason still. Indeed, one knew that the ground had always changed, during his long existence. But, since a species was to be in harmony with the environment to survive and its environment changed constantly, the species were also to then change in order to maintain balance. Lamarck had just discovered the fault of natural theology and the Créationnisme by introducing the factor of the geological time of the ground. It was possible to imagine that God had created living organisms perfectly adapted to their environment, but only in one static world. However, how of the species could they remain perfectly adapted to an environment continuously changing? Only, if they changed while adapting to the medium.

France due to await the appearance of the theory transformist of Lamarck so that a true debate on the evolutionism bursts. Contrary to Buffon (1707-1788) which moderated its positions, Lamarck was not afraid of the confrontation. Unfortunately, it undergoes of them hard the consequences when it passed, without answering, the last years of its life hammered by the attacks of Vat discrediting its theory. However, fortunately for the transformism, the death of Lamarck did not mark the end of the evolutionism in France, because in 1825, the zoologist Etienne Geoffroy Saint-Hilaire (1772-1844), founder of the Tératologie, science studying the monsters of nature, declares himself, in the line of Lamarck, evolutionist.

Although the transformism of Saint-Hilaire is different from the transformism of Lamarck with which one should not confuse it, one always finds there the idea of the heredity of the assets. Geoffroy Saint-Hilaire will take part in the transformism mainly in what one will call the controversy of the “crocodiles” of Caen against Cuvier, celebrates it at the time paleontologist champion of creationism.

See too

political Direction of the word: absorption of the opposition

External bonds

Theory of the evolution
Origin of life

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