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Lamarck, Chevalier de (1744–1829)

LAMARCK, CHEVALIER DE
(17441829)

Jean Baptiste Pierre Antoine de Monet, Chevalier de Lamarck, the French biologist and formulator of the first comprehensive theory of evolution, was born at Bazentin-le-Petit, a village in northeastern France. As a youth he studied briefly for the priesthood, but later withdrew to follow the family tradition of army service. While in Paris recovering from an injury and intermittently studying medicine, he met Jean-Jacques Rousseau, through whom he became interested in botany. This interest led to investigations that culminated in the publication of a large work on the flora of France, which brought Lamarck immediate fame and election to the Academy of Sciences. From 1783 to 1793 he held a small post at the Jardin du Roi, which was reorganized and expanded along lines proposed by Lamarck to include a museum of natural history and twelve professorial chairs. The last of these, for the study of invertebrates, went almost by default to Lamarck himself. Hence, at the age of fifty he began his indefatigable labors as a zoologist. These labors led to his conclusion, at some time between 1794 and 1802, that a transmutation of animal species had taken place. He expounded his views in a succession of important works: Système des animaux sans vertèbres (Paris, 1801), Rechėrches sur l'organisation des corps vivans (Paris, 1802), Philosophie zoologique (2 vols., Paris, 18091830, translated by H. Elliot as Zoological Philosophy, London, 1914), and Histoire naturelle des animaux sans vertèbres, (7 vols., Paris, 18151822). The significance of Lamarck's contribution was scarcely appreciated by his contemporaries. When he died at the age of eighty-five, blind and poor, he had become a forgotten man. His body was buried in a pauper's grave whose exact location is unknown.

System of Nature

Lamarck aspired to produce a large-scale "system of nature" set in a deistic framework. He held that nature, "the immense totality of different beings," is neither eternal nor self-explanatory. It is the creation of a "Supreme Author" who brought matter into being and instituted the world order by means of laws that govern whatever happens. Within nature, change is universal. But nature in toto is unchangeable and "should be regarded as a whole constituted by its parts, for a purpose which its Author alone knows." This whole, however, is as distinct from the Creator as a watch is from the watchmaker. Hence, nature has productive powers of its own that the sciences can properly interpret in mechanical and materialistic terms. The system that Lamarck originally planned was to have included sections on physics, chemistry, meteorology, geology, and biology. Some of his writings did, in fact, discuss all these topics, but what appeared can hardly be said to form a unified scheme. His attention was increasingly occupied by his reflections on living things, the science of which he named biology in 1802.

Evolution

Lamarck effected a breakthrough to an evolutionary conception of nature by bringing together several lines of thought. His geological studies convinced him that Earth had endured for an immense span of time, during which it had undergone many changes of a gradual sort, especially in its surface features. His observation of fossils supported the conclusion that animal life had existed for a large part of geological time and had also undergone gradual changes. Hence, species must be mutable, and their apparent stability is due to man's limited time perspective. Furthermore, organisms are simply physical bodies whose parts are highly organized. Thus, Lamarck was opposed to vitalism. "Every fact or phenomenon observed in a living body," he held, "is a physical fact or phenomenon, and a product of organization" (Histoire naturelle des animaux sans vertèbres, Vol. I, p. 53). Accordingly, he accepted the conclusion that a "spontaneous generation" of organisms had occurred. Animals and plants represent two independent lines stemming from two distinct types of spontaneous generation that utilized chemical materials differently. These materials are wholly inanimate and display none of the characteristic properties observed in the organisms they constitute.

Perfecting Power in Nature

The history of living things on Earth reveals a steady increase in the complexity of their organization, a process by which they have also been perfected. "Nature has produced all the species of animals in succession, beginning with the most imperfect or simplest, and ending her work with the most perfect." Man is the being who exemplifies the highest excellence of bodily organization, and he thereby provides "the standard for judging the perfection or degradation of other animal organizations." Lamarck's thought at this point was influenced by the idea of the "great chain of being," the infinitely graded series of forms from highest to lowest, which was a doctrine congenial to eighteenth-century deism. Since, in his evolutionary approach, the series came into existence from the bottom, Lamarck attributed it to a perfecting power inherent in nature. The postulating of this perfecting power is the feature of Lamarck's evolutionism that separates it most sharply from that of Charles Darwin.

Causes of the Power of Evolution

If the environment were unchanging, the perfecting power of nature would produce a simple, linear sequence of organisms. But the environment is ceaselessly changing, and, as a result, evolution is "deflected" from a linear path into the "branching" pattern actually found among plants and animals. The mechanism by which the branching pattern is formed consists of a group of causal factors often mistakenly supposed to be the whole of Lamarck's theory, instead of just a part of it.

The causal factors are specified in several "laws"two in Philosophie zoologique and four in Histoire naturelle des animaux whose purport can be summarized as follows. The organs and habits by which animals maintain their adaptation to the environment are controlled by bodily fluids that are constantly in motion. Animals whose structure is so elementary that they have no faculty of feeling are acted on mechanically by environmental changes. New motions of the internal fluids are set up, and these give rise to adaptive alterations in the organs and habits. The case is different with animals whose structure is complicated enough to enable them to feel wants or needs (besoins ). When the environment of these animals changes, new needs are felt, and each need, "exciting their inner feeling (sentiment intérieur ), forthwith sets the fluids in motion and forces them toward the point of the body where an action may satisfy the want experienced" (ibid., p. 185). If a suitable organ already exists at that point, it is immediately incited to action. If not, the felt need gradually causes the organ to be generated, "provided the need be pressing and continuous." Everything thus acquired by an individual animal during its lifetime is preserved by heredity (génération ) and transmitted to that individual's progeny. The operation of these causal factors, superimposed on the general perfecting tendency of nature, accounts for all that has happened in evolution.

Man

Man's place in this theory was a topic that Lamarck understandably treated with caution. He stressed man's "extreme superiority" over other living things because of his possession of reason, although anatomically he differs only in degree from monkeys and apes. Is it not plausible to suppose that the differences have been "gradually acquired" over a long period of time? "What a subject for reflection," Lamarck commented, "for those who have the courage to enter into it!" He himself dared in a short section of Philosophie zoologique to outline a hypothetical explanation of how apelike beings might "at length be transformed" into manlike beings, able to walk upright, to use tools, and to develop "the marvelous faculty of speaking." Throughout the process, changed habits would produce new wants and new capacities, until true human beings appeared. "Such are the reflections which might be aroused, if man were distinguished from animals only by his organization, and if his origin were not different from theirs." At this point Lamarck's courage apparently gave out.

Assessment

Despite the comprehensiveness of his outlook, Lamarck failed to formulate a unified theory of evolution. Therefore, he had to conclude that the diversification of plants and simple animals was due to mechanical factors alone, whereas in the case of complex animals an important psychological and teleological factor was operative. He held that no species had ever been totally extinguished, in spite of what the fossil evidence indicated, because he believed that the plan of the Supreme Author of the universe would not allow such wastage. His acceptance of the perfecting tendency obliged him to affirm that there are really two animal series: the grand one from simple to complex, and the particular, branching series that have deviated from it. Above all, his theory demanded not only that modifications acquired by parents during their lifetime should affect their offspring, but also that they should affect the same parts in the offspring as in the parents and should become a permanent hereditary feature in that line of descent, regardless of later modifying factors. Modern genetic research has shown strong, although perhaps not conclusive, reasons for believing that such an "inheritance of acquired characteristics" cannot occur. None of these difficulties, however, can detract from the greatness of Lamarck's contribution. "He first did the eminent service," Darwin remarked, "of arousing attention to the probability of all change in the organic world being the result of law, and not of miraculous interposition."

See also Darwin, Charles Robert; Darwinism; Evolutionary Theory; Laws of Nature; Rousseau, Jean-Jacques; Vitalism.

Bibliography

Cannon, H. G. Lamarck and Modern Genetics. Springfield, IL: Thomas, 1960.

Gillispie, C. C. "The Formation of Lamarck's Evolutionary Theory." Archives internationale d'histoire des sciences 35 (1956): 323338.

Gillispie, C. C. "Lamarck and Darwin in the History of Science." American Scientist 46 (1958): 388409.

Landrieu, Marcel. Lamarck. Paris: Société Zoologique de France, 1909.

Packard, A. S. Lamarck, the Founder of Evolution. New York: n.p., 1901.

Russell, E. S. Form and Function. Cambridge, U.K.: Murray, 1916. Ch. 13.

Wilkie, J. S. "Buffon, Lamarck and Darwin." In Darwin's Biological Work, edited by P. R. Bell, 262307. Cambridge, U.K.: Cambridge University Press, 1959.

T. A. Goudge (1967)

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