Lamarck, Jean Baptiste Pierre Antoine De Monet De

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Lamarck, Jean Baptiste Pierre Antoine De Monet De

(b. Bazentin-le-Petit, Picardy, France, 1 August 1774; d. Paris, France, 28 December 1829)

botany, inveterate zoology and paleontology, evolution.

Lamarck was the youngest of eleven children born to Marie-Françoise de Foundations de Chuignolles and Philippe Jacques de Monet de La Marck. His parents were among the semi-impovershed lesser nobility of northern France; his father, following family tradition, served as a military officer. It was primarily economic and social considerations which led his parents to select the priesthood ads his future career. Lamarck, at about age eleven, was sent to the Jesuit school at Amiens; he was not, however, interested in a religious career and much preferred the military life of his father and older brothers. When his father died in 1759, Lamarck left school in search of military glory. Within a few years he was fighting with a French army in the Seven Years’ War. After the war was over, he spent five years (1763–1768) at various French forts on the Mediterranean and eastern borders of France. It was during this period that he began botanizing; his military transfers served to acquaint him with highly diverse types of French flora.

In 1768 Lamarck left military service because of illness and after several years found a job in Paris bank. He subsequently studied medicine for four years and became increasingly interested in meteorology, chemistry, and shell collecting.

Lamarck’s personal life was marked by tragedy and poverty. He had three or four wives and eight children. In 1777 he began a liaison with Marie Rosalie Dlaporte, marrying her, fifteen years and six children later, as she was dying. In 1793 he married Charlotte Victoire Reverdy, by whom he had two children; she died in 1797. The following year he married again; Julie Mallet died childless in 1819. There is some indication that he married for a fourth time, but no documents to support this can be found. Lamarck’s health began to fail in 1809, when he developed eye problems; in 1818 he became completely blind but was able to continue his work by dictating to one of his daughters. When he died in 1829, the family did not have enough money for his funeral and had to appeal to Académie des Sciences for funds. His belongings, including his books and scientific collections, were sold at public auction; he left five children with no financial provisions. Of these, one son was deaf and another insane; his two daughters were single and without support. Only one child, Auguste, was financially successful as an engineer; he was the only one of the off spring to marry and have children.

Botany . Lamarck’s recognition by the French scientific community resulted from the publication of his Flore francoise in 1779 (not 1778 as the title page says). His innovation was the establishment of dichotomous keys to aid in the identification of French plants; by eliminating large groups of plants at each stage through the use of mutually exclusive characteristics, the given name of any plant could be rapidly determined. This “method of analysis,” as Lamarck called it, was much easier to use in identifying plants than Linnaeus’ artificial system of classification, which was based on sexual differences among plants or the natural methods of classification then developing in France with the work of Adanson, Bernard de Jussieu, and Antoine Laurent de Jussieu. Landmarck’s new approach and his criticisms of Linnaeus impressed Buffon, who arranged to have the Flore published by the government. The first of the three volumes contained a theoretical “Discours préliminaire” which, among other things, explained the method of analysis and a lengthy exposition of the fundamentals of botany. The other two volumes listed all known French plants according to his method of classification and provided good descriptions of each species. The Flore was one of the first French works to include the Linnaean nomenclature as well as that of Tournefort. Written in French rather than Latin, the Flore was an immediate success and the first printing was sold out within the year; in 1780 the work was reprinted. Lamarck had various plans for a new edition but was unable to carry them out for lack of funds. Finally, in 1795, the Flore was reprinted; although it did not differ from the first edition, it was called a second edition. In 1802 Lamarck, who was too busy doing other things, turned the preparation of a new edition over to A. P. de Candolle, who published what is called the third edition in 1805. Candolle made major revisions, replacing Lamarck’s system of classification with that of A. L. de Jussieu and revising the section on the fundamentals of botany to include new scientific discoveries. Ten years later this third edition was reprinted and another volume was added to include species previously unknown or overlooked.

Lamarck’s other major work in botany was his contribution to the Dictionnaire de botanique, which formed part of the larger Encyclopédie méthodique. He wrote the first three and a half of eight volumes; they were published in 1783, 1786, 1789, and 1795. Lamarck composed a long “Discours préliminaire,” articles on all aspects of botany including classification and the structures of plants, and articles describing specific plants and their classifactory groupings. The companion piece to the Dictionnaire, the Illustration des genres, appeared in three volumes in 1791, 1798, and 1800. It included about 900 plates, descriptions of general arranged according to Linnaeus’system of classification, and a listing of all known species in these genera. Lamarck himself had identified several new genera and species; he published these discoveries as articles in various publications from 1874 to 1792.

In addition to devising a new and useful method of the identification of plants and doing systematic botany, Lamarck demonstrated a number of theoretical and philosophical interests in his botanical works. In the “Discours préliminaire” of the Flore Lamarck made his first attempt to formulate a natural method of classification for the vegetable kingdom. His aim was to discover the position every vegetable species should occupy in a graduated unilinear chain of being on the basis of comparative structural relationships. Unable to achieve this, he had to settle for a natural order at hte level of genera and even this was very tentative. Although he shared a common assumption of the time, that a natural classification would begin with the most complex and descend to the simplest organism, he found that in practice it was easier to work in the opposite order. This order would later be an essential feature of his evolutionary theory. Lamarck intended to develop his natural method in a work which was to be entitled Théātre universel de botabique The proposed work was to include all members of the vegetable kingdom, not just those found in France; it was never written.

In the “Discours préliminaire” of the Flore, Lamarck showed the orientation of a naturalist philosopher concerned more with the broad problems than the little facts, as he called them. He conceived of nature as a whole composed of living and nonliving things, the former divided into plants and animals. It was the view of the whole, it processes, and interrelations which really interested him.

Lamarck, in the same work, demonstrated his awareness of the important influence of the environment, especially climate, on vegetable development. He noted that two seeds from the same plant growing in two very different environments would become two apparently different species. Lamarck was particularly conscious of the changes plants undergo in artificial cultivation and he referred to such changes as degradations, the term he first used in describing evolutionary processes in 1800. In 1779, however, Lamarck still believed in fixed species and thought of the environment as the factor responsible for the production of varieties; by 1800 he had extended these views on the production of varieties to the origin of all organisms below the level of classes.

In 1779 Lamarck also demonstrated his genetic approach to a subject; the present is understood by tracing the historical steps that produced it, beginning with the most primitive level and working up through time to the more complex. Lamarck shared with the Philosophers a belief in thee idea of progress in human knowledge, which is clearly seen in his brief history of botany. Increasing progress over time is almost inevitable if circumstances are favorable. He was later to apply such a conception to natural as well as human history.

In the Dictionnaire de botanique Lanmarck developed the theoretical and philosophical ideas he had advanced in the Flore. Thee “Discours préliminaire” was an expanded version of the history of botany from the Flore and it showed even more fully Lamarck’s belief in the idea of progress in his search for natural method of vegetable classification. Following some suggestion from A. L. de Jussieu, he decided that a hierarchical arrangement could be established only for the larger groupings or classes of plants. A focus on classes rather than genera or species would later be an important part of his evolutionary theory. Lamarck’s new views were set forth in the article “classe,” in which he listed the classes of plants, arranged from the most compled to the least complex; placement on the scale was determineed by relative structural complexity. To complete the realm of living organisms, Lanmarck presented a parallel series of descending classes for the animal kingdom. In pointing out the similarities between plants and animals, he laid the foundations for his biology. In another table the nonliving natural productions were also arranged in order of decreasing complexity. Lamarck held that all mineral substances were produced by organic beings as they and their waste products decayed over time and their debris underwent successive transformations until the simple element level was reached. The fact that Lamarck drew up these tables of comparison shows his concern with seeing nature as a whole.

During the 1790’s, Lamarck’s interest and studies turned away from botany to new fields. After 1800, when he began advocating his theory of evolution, he wrote only one work specifically dealing with botany. His two-volume Introduction é la botanique (1803) formed part of the fifteen-volume Historie naturelle des végétaux; the rest of the work was written by Mirbel. This study of the vegetable kingdom was in turn part of the larger eighty-volume Cours complet d’histoire naturelle pour faire suite á Buffon eidted by castel. Lamarck’s Introduction was his only botanical work to include his evolutionary theory. He stressed that for the vegetable kingdom a natural order of classification beginning with the simplest class and ending with the most complex class reflected the order which nature had followed in producing these groups in time. Although this was his last botanical work, Lanmarck did not stop thinking about the vegetable kingdom. He discussed it in all of his evolutionary works and drew a number of example from it.

Institutional Affiliations . Lamarcl’s election to the Académie des Sciences as an adjoint botanist was engineered by Buffon in 1779. He was promoted to an associate botanist in 1783 and became a pensioner in 1790. The Academy was suppressed in 1793, during the Terror; it was reorganized two years later as part of the Institut National des sciences et des Arts. From 1795 until his death, Lamarck was a resident member of the botanical section. Until his health failed, he attended meetings regularly and prepared a number of reports on works submitted to the Academy.

In the 1790’s Lamarck took an active role in the newly formed Société d’Histoire Naturelle, which included the prominent French naturalists of the time. He helped edit several of its publications and contributed a number of articles on botany and invertebrates to them.

Lamarck’s most significant institutional affiliation was with the Jardin ddu Roi, which had become an important scientific center in the second half of the eighteenth century under the leadership of Buffon. From 1788 until 1793, Lamarck held various minor botanical positions there. During the French revolution, when all the institutions of the ancien régime were being subjected to critical examination, suggestions were made for the reorganization of the Jardin ddu Roi, among them a memoir by Lamarck. in 1793, when the academies were suppressed as privileged institutions of the old order, the Jardin du Roi was transformed into the Muséeum National d’Historie Naturelle. The botanical positions were filled by others and Lamarck was made a professor of Zoology for the study of “insects and worms,” a group of animals which he renamed “invertebrates.” While this represented a rather drastic shift in fields for him, Lamarck was not unhappy about it, for he had been developing an interest in these animals. His new duties consisted of giving courses and classifying the large collection of invertebrates at the museum. He also took an active part in the administration of the new institution. Lamarck’s own work benefited from contacts with his colleagues and their scientific investigations at the museum.

Chemistry . The first long works that Lamarck published after thee reorganization of the museum dealth not with invertebrates but with chemistry, a subject in which he had been interested for many years. He had begun to study chemistry in the 1770’s, when the four-element theory (earth, air, water, and fire) was generally accepted in France. He continued to believe in the four elements throughout his life despite in the four elements throughout his life despite the work of Lavoisier and the chemical revolution; for this reason his chemistry has often been dismissed as worthless speculation. Yet Lamarck took it very seriously, and it was an important part of his ideas about nature and evolution.

Lamarck’s first work in the field, Recherches sur les causes des principaux faits physiques, was begun in 1776. It was submitted to the Académie des sciences in 1780 and received an unfavorable report; it was finally published in 1794, after teh Academy had been suppressed. Lamarck devoted two other ful-length studies to chemistry: Ré;futation de la théorie pneumatique (1796) and Mé;moires de physique et d’histoire naturelle (1797). He also published two articles in 1799; they were reprinted at the end of his Hydro-géologie (1802), which contained a long chapter relating his chemical theories to his geological theories. Although Lamarck’s chemical views were ignored, he continued to hold them; they appear with signs of increasing paranoia in his major evolutionary works. They play the most prominent role in Recherches sur l’organisation des corps vivans (1802), the first full-length exposition of his evolutionary theories.

In Lamarck’s four-element theory, differences between compounds depended on both the number and proportion of the elements and the relative strengths of the bonds between the elements in the constituent molecules. Furthermore, each element had a natural state in which it demonstrated its real properties and several modified states in which it was present in compounds. The most important of the four elements in Lamarck’s chemistry was fire, which existed in three main states: a natural one and two modified forms, which were fire in a state of expansion (or caloric fire) and fixed fire. Using these three main states and their many internal modifications, Lamarck attempted to account for a great number of chemical and physical phenomena such as sound, electricity, magnetism, color, vaporization, liquefaction, and calcination. Later, in his theory of evolution, he added life as another phenomenon to be explained by activity of fire. For Lamarck, fire not only explained many processes, it also was a constituent principle of compounds. HE attempted to show how chemical substances in their various states depended on differing amounts of fixed fire. One temporary form of fixed fire was phlogiston.

Lamarck belived that only living beings could produce chemical compounds. Plants combined free elements directly to produce a number of substances of varying complexity. These is turn were elaborated by the different animals eating the plants, the more complex substances being produced by those animals with the most highly organized physiological structure. The process of compound formation involved modification of the elements away from their natural state and the more complex the substance, the greater the modification. once the forces of life were removed, by death or the elimination of waste products, the compounds began to disintegrate. The natural tendency of all compounds, therefore, was to decompose until the elements returned to their natural state, in the process producing all known inorganic substances. For the mineral kingdom there was a chain of being with continous degradation from the most complex to the simplest; this chain was composed of individuals rather than species or types of minerals. Lamarck’s first statement of his theory of evolution in 1800 showed a similar thought pattern: degradation and irrelevance of species.

In his chemistry, Lamarck showed a speculative orientation and an emphasis on nature as a whole with many interrelated parts and processes. His distinction between the living and the nonliving was crucial to his biology and his view of the mineralogical chain of being was basic to his geology. His chemistry was also later to be very important in his theory of evolution. It was used to provide a materialistic definition of life and to explain its maintenance, appearance (both through reproduction and through spontaneous generations), and the way in which living organisms gradually evolve, including the emergence of the higher mental faculties. Fires, as understood by Lamarck, was the key element in all of these explanations.

Meteorology . Lamarck’s work in meterology was similar in may respects to that in chemistry. although one of his earliest scientific interests, he did not publish anything until the late 1790’s; he experienced the same general lack of reception of his work in chemistry. Meteorology was the first scientific area in which Lamarck prepared a memoir and one which was well received by the Academy. The manuscript of this unpublished memoir (Muséum National d’Historie Naturelle, Paris, MS 755–1) shows that as early as 1776, Lamarck was interested in the effects of climate on living organisms. It is highly probable that Lamarck’s interest in chemistry resulted from his concern with certain aspects of meteorology. His general approach to science is also evident in this early manuscript: his emphasis is on the general principles, and he manifests disdain toward those devoted solely to the collection of little facts. The extent to which Lamarck saw his Meteorology as part of his whole view of nature is indicated later in his Hydrogéologie, in which he states that a terrestrial physics would include three subjects: meteorology, hydrogeology, and biology. He orginally intended to write a work dealing with these areas but decided to postpone the sections on meterology and biology until he had done further research.

Lamarck continued his study of metorology in the 1780’s, while he was involved in botanical studies; his awareness of the importance of climate for plants has already been mentioned. In 1797 he began publishing articles on meteorology and attempting to provide theoretical explanations for factors causing weather change. Three years later he started publishing the Annuaire météorologique. It has often been said that Lamarck wrote these volumes with the sole intention of earning money, but he showed too great an interest in them and in defending his theories for that to have been the case. It was surely no coincidence the he was assembling his meteorological studies at the same time he was elaborating his theory of evolution (the last Annuaire was published in 1810). Since climate was an important factor in his theory, it would be important to seek the laws regulating changes in climate and therefore perhaps be able to predict or understand changes in organisms more fully.

Lamarck’s metorology was devoted to a search for those laws of nature which regulate climatic change. The search was more important than the speculative theories he devised, for it indicates certain connections with the Enlightement; he assumed that there must be simples discoverable laws governing weather changes. He also had grounds to think that such laws must exist because of Frabklin’s success in identifying lightning and terrestrial electricity; he greatly admire Franklin. In addition, a number of his contemporaries were studying meterological phenomena, improving instruments, and theorizing. Lamarck was familiar with their work and used it as a point of departure for his own.

As in botany, Lamarck was attracted to his history and progressive development of meteorology. One might also say that he was concerned with a natural classification of meteorological phenomena. Finally, his theoretical considerations indicate an important though pattern; he tried to explain all meteorological change as the result of one general cause (the moon) with irregularities product by local circumstances.

Lamarck did have one public success with his meteorology. He recommended that the French government establish a central meteorological data bank. Following this suggestion, Chaptal established such a program in the ministry of the interior in 18700. One of Lanmarck’s concerns was that the daily observations from all parts of France be made in accordance with standardized procedures and instruments. The project and Lamarck’s work in meteorology ended in 1810, when Napoleon ridiculed Lamarck’s Annuaire.

Invertebrate Zoology and Paleontology . When the Muséum d’Histoire Naturelle was established in 1793 and Lamarck made professor of “insects and worms,” he had the tasks of organizing the museum collection and giving courses, beginning in the spring of 1794. His only previous connection with the invertebrates was his interest in shell collecting. He was, however, a good friend of his colleague, Jean-Guillaume Bruguiére, who was considered an expert on invertebrates, especially the mollusks. When Bruguiére died in 1798, Lamarck finished his Histoire des vers for the Encyclopédie méthodique. Lamarck’s published works in the field include a number of articles, in which he identified new genera and species and put forth some theoretical considerations, and books, the most important of which were Systéme des animaux sans vertébres (1801) and his seven-volume major work, Histoire naturelle des animaux sans vertébres (1815–1822).

Lamarck developed a system for the natural classification of invertebrates based on the anatomical findings of Cuvier. As in botany, the natural order consisted of classes arranged in a linear fashion from most complex to least complex. Such a series provided clear examples of degradation in anatomical structure and physiologic function, as one system after another disappeared. Lamarck spoke of this degradation well before he advocated his theory of evolution, and that theory was first put forth as one of degradation. His study of invertebrates also helped him refine his definition of life, for the simplest organisms indicated the minimum conditions necessary for life. The origin (generation) of these simplest animals raised problems whose answer seemed to be spotaneous generation.

Burkhardt has pointed out (1972) that Lamarck came to be regarded as an expert in conchology and the successor to Bruguiére. Lamarck made an important contribution to the classification of shells in his “Prodrome d’une novelle classification des coquilles” (1799), in which he established 126 genera. Any attempt to classify shells immediately raised the problem of what to do with fossil forms. According to Burkhardt, the pressing question of the late 1790’s was whether there any similarities between living and fossil forms. If the answer were no, the way was open to a belief in extinction, especially extinction brought about by some catastrophe. The issue being debated involved vertebrates as well. Cuvier and others were making impressive discoveries of large mammalian fossils which seemed to have no living analogues. There were some people at the museum, however, who were discovering analogues. Alexandre Brongniart and, slightly later, Faujas de Saint-Fond and étienne Geoffroy Saint-Hilaire were investigating similarities between some fossil and living reptiles.

several naturlists, including Faujas, expected Lamarck’s investigations of shells from living and fossil forms to resolve the issue. His work did reveal a number of analogues. The question then became on eof explaining the similarities and differences. Although the existence of analogues would rule out the possibility of a general catastrophe, more limited violent events could have produced some species extinction which would account for the failure to find analogues in many cases. There were, Burkhardt suggests, two other ways to explain the differences: migration or evolution. Lamarck, unable for philosophical reasons to entertain the possibility of extinction and unconvinced of migration as plausible way to account for all the differences, chose an evolutionary explanation sometime in late 1799 or early 1800. differences between living and fossil forms existed precisely because organisms had undergone change over time; Lamarck regarded this position as one of the strongest arguments against extinction. The study of fossil forms led Lamarck to conceive of nature as existing in time. Lamarck has often been called the founder of invertebrate paleontology. His most important work on the subject was Mémories sur les fossiles des environs de Paris (1802–1806). The “Introduction” to this work discusses the significance of fossils for a theory of the earth.

Geology . Lamarck’s geology was closely connected with his work in other fields. His Hydrogéologie, which grew out of a 1799 memoir presented to the Academy and his work in invertebrate paleontology, was published in 1802. He originally intended it to be a much broader work, as the manuscript shows (Muséum National d’Histoire Naturelle, Paris, MS 756–1, 2). It was to have been a terrestrial physics including meterology, geology, and biology, a term he coined. He had not only a sense of the interrelation of fields but, within geology, a vision of the whole. He saw all of nature working according to similar principles: general natural tendencies producing gradual change over long periods of time, with local circumstances explaining the irregularities. His approach to geology was similar to that in other sciences: concern with the general principles and contempt for those who interested themselves too much with the specifics.

Although Lamarck’s geological views were not original (he was strongly influenced by Buffon and Daubenton, among others), they were an important part of his conception of nature. His preoccupation with marine fossil shells had a decisive influence on his choice of geological theories. Since such shells had to have been laid down in water, he needed a theory to explain how this was possible. As in his meteorology, he used the moon as the main cause, in this case of a constant slow progression of the oceans around the globe. The main geological force was water acting according to uniformitarian principles over millions of years. The substances of the mineral kingdom were produced by the progressive disintegration of organic remains; water operated on these products to produce geological formations such as mountains. Lamarck’s uniformitarianism and great geological time scale have led some to say that he was his own Lyell. Some historians have thought that Lamarck’s perception of a slowly changing environment and the resulting necessity of organisms to change or become extinct (a possibility he could not accept) led him to his theory of evolution.

Theory of Evolution . Before beginning a discussion of Lamarck’s theory of evolution, it is important to point out that he never used the term “evolution” but, rather, spoke of the path or order which nature had followed in producing all living organisms. “Evolution” is used here only as a shorthand form for Lamarck’s longer phrases.

Lamarck’s first public presentation of his theory of evolution was in his opening discourse for his course on invertebrates at the museum in 1800; it was published the following year at the beginning of his Systéme des animaux sans vertébres. The evolutionary views sketched in the discourse leave much to be desired in terms or organization and explanation. They are, however, very much a part of a total view of nature, many aspects of which Lamarck had long accepted. Natural products consisted of living and nonliving things; in two branches of living organisms, Lamarck pointed out the “degradations” in structural organization of the larger classificatory groupings or “masses” as one moved down the series from the most complex to the simplest. He indicated his lack of clarity about the new views he was proposing by using the term “complication” interchangeably with “degradation.” Nature, after having formed the simplest animals and plants directly, produced all others from them with the aid of time and circumstances. In 1800 Lamarck did not explain how spontaneous generation occurred or how unlimited time and varied circumstances produced all other organisms. He did suggest that for animals, changing circumstances and physical needs led to new responses which eventually produced new habits; these habits tended to strengthen certain parts or organs through use. Gradually new organs or parts would be formed as acquired modifications were passed on through reproduction.

The great expansion of Lamarck’s ideas occurred between 1800 and 1802, when the Recherches sur l’organisation des corps vivans was published. Much of the work was devoted to documenting the “degradations” in organization of the larger groupings of animals, from mammals to polyps. He was, however, more aware of the need to turn this series over so that it would correspond to the order of production in nature and time and thus be a really natural method of classification. Once he began to think in terms of increasing levels of complexity, he needed a mechanism to propel; change; otherwise one would have only polyps in the world. He therefore began to talk of a natural tendency in the organic realms toward increasing complexity. Lamarck is not clear or consistent about the manner in which this natural tendency operates; often it seems to function like a moving escalator. At other times it can best be understood by a stairlike construction where descent is more directly tied to the historical past although Lamarck never suggests any dates marking the appearance of particular forms of life.

Lamarck’s conception of a natural tendency toward increasing complexity provided a perfect complement to his views of the mineral kingdom with the opposite natural tendency. In both cases a long time span allowed nature to do her work and local circumstances explained irregularities. Among living beings, irregularities included all organisms below the level of the “masses,” which usually meant classes but sometimes was extended to orders and families, never to genera and species.

In 1802 many of the additions were designed to explain in more detail why and how evolution happened; Lamarck’s chemistry was essential to those explanations. He had to face the crucial problem of what happened at the lower ends to the vegetable and animal series. Rejecting the vitalist views of such contemporaries as Bichat, Lamarck defined life in physical terms. Life resulted from a particular kind of organization and a general tension maintained by the stimulation of the subtle fluids of his chemistry, especially modified forms of fire.

Spontaneous generation of animals, which Lamarck held was analogous to fertilization, occurred when heat (or calroic), sunlight, and electricity acted on small amounts of unorganized, moist, gelatinous matter to produce the simplest animals. He later specified that the simplest animals. He later specified that the simplest plants were spontaneously generated when the same physical substances organized moist, mucilaginous matter. The first traces of organic organization formed by the subtle fluids were simple structures capable of containing certain fluids, such as water, and more complex substances. From this point on, the natural tendency of organic movement toward increasing complexity could take over. In plants and simple animals, the physical cause of this tendency was the constant agitation of the contained fluids by the subtle fluids of the environment (especially the matter of heat), which were not containable and could penetrate the living organism. The result of this agitation was the gradual hollowing out of passages and tubes and the eventual formation of organs and then primitive systems.

Animals with circulatory systems were less directly dependent on the environment because, Lamarck believed, the matter of heat was constantly disengaging from the blood and thus providing an internal stimulus for greater development. Such was the materialistic explanation he gave for the origin of the larger groupings of plants and animals. All differences below that level were explained by variations in the movement of the containable and subtle fluids due to different circumstances, especially the temperature of the environment, and to changing life styles resulting in new habits. Through the use of parts, containable fluids were concentrated and the formation of new organs was accelerated. With new organs and systems, new faculties appeared. Acquired changes were preserved through inheritance.

In 1802 Lamarck death briefly with the upper limit of the animal series—man. He cautiously suggested that man was the result of the same processes that had produced all other living organisms. The major obstacle to the inclusion of man in the evolutionary process was his higher mental faculties. At the end of the Recherches, Lamarck offered a possible solution to this problem. Using his chemistry and comparative anatomy, he attempted to provide a materialistic explanation for the functioning of the nervous system. Following Haller’s distinction, he maintained that while all animals exhibit irritability, only those with a nervous system experience sensibility or feeling. The degree to which an animal possessed the latter faculties depended on the level of complexity of the nervous system and the movement of the nervous fluid, which was a modified form of fire, similar to electricity. This subject of the evolution of the higher mental faculties underwent major development in the Philosophie zoologique (1809).

This work is the best-known and most extensive presentation of Lamarck’s theory of evolution. An expanded version of the 1802 Recherches, it is divided into three sections. The first is a more eleborate analysis of the evidence for increasing levels of “complication” observed in the major classificatory groupings of animals and plants. It also presents in more detail Lamarck’s two-factor theory of evolution: the natural tendency toward organic complexity as a way of explaining the hierarchical organization of the “masses” and the influence of the environment as the factor responsible for all variations from this norm. In the second part of the Philosophie zoolgique, Lamarck developed his views on the physical nature of life, its spontaneous production resulting in simple cellular tissue, and its characteristics at the simplest level, the lower ends of the plant and animal series. While these two parts were very important in summarizing many of his evolutionary views, they do not differ significantly from the positions of 1802.

The third part contains the most important additions to the earlier theories. In this section Lamarck deals in great detail with the problem of a physical explanation for the emergence of the higher mental faculties. Some of the eighteenth-century materialists, such as Maupertuis, had attempted to avoid the question of emergence by making thought a property of matter. Some religious figures went to the other extreme and limited thought to man and his soul. Lamarck’s breakthrough was tying a progressive development of higher mental faculties in a physical way to structural development of the nervous system. He had already advanced explanations for the evolution of new structures and systems, and the theories on the nervous system were an extension of these earlier views. Higher mental faculties could emerge precisely because they were a product of increased structural complexity, and in all this a physically defined nervous fluid was crucial. For Lamarck one of the most important events in the evolutionary process was the brian, because at the point animals began to form ideas and control their movements.

There has been great misunderstanding of Lamarck’s concept of sentiment intérieur, or inner feeling, as a directing factor in the functioning and evolution of higher animals. Lamarck never believed that the giraffe has a longer neck because it consciously wanted one. Rather, he observed that higher animals were capable of voluntary motion which might become habit (as in a search for food or avoidance of danger) and of involuntary motion, or what we would call reflex action. Lamarck attempted to account for such behavior through the mechanism of the sentiment intérieu, an internal physical feeling resulting from agitation of the nervous fluid. The brain of an animal with an internal physical need, such as hunger, would direct the nervous fluid so as to cause muscular motion to satisfy that need. If this action were constantly repeated, new organs would eventually result. On the other hand, a sudden, strong stimulus, such as a loud noise, would produce a reflex action because of a particular perturbation of the nervous fluid.

The concept of the sentimetn intérieur included not only the direct interaction with the physical world but also the more sophisticated level. It could be affected, particularly in human beings, by ideas or moral sensations. Such a view was in keeping with an extension of Condillac’s sensationalist psychology and epistemology, especially as expressed by Cabanis and the Idéologues. Moral and aesthetic reactions were thus as physically caused as instinctive or reflex ones; the only difference was that between primary or secondary causation. It is not surprising that Lamarck has many references to Cabanis on the relationship between physique and morale. Lamarck felt he had provided a materialistic account for all the activities involving the nervous system, including instinct, will, memory, judgment, understanding, and imagination. He further developed these views in his last publication, Systéme analytique des connaissances positives de l’homme (1820).

Next to the Philosophie zoologique, Lamarck’s best-known work dealing with evolution is the 1815 “Introduction” to his impressive seven-volume Historie naturelle des animaux sans vertébres (1815–1822). In this work he summarized his evolutionary views in four laws. The first law concerns his principle of the natural tendency toward increasing organic complexity as observed in the larger groupings of the plant and animal series. The other three laws explain how changes occurred and account for irregularities below the class level. The second law deals with the way new organs evolve by the indirect influence of the environment of an animal. The use-disuse principle, or third law, accounts for changes in the body as a result of new habits; this principle was not new with Lamarck but was generally accepted. The last law, dealing with the inheritance of acquired characteristics, was necessary after positing a slow, gradual evolution; without it Lamarck would have been unable to explain cumulative change and the emergence of new structures. Too much energy has been spent attacking this last laws; because it represents an assumption not believed today, it has been said that this disproves Lamarck’s whole theory of evolution. The historical context of Lamark’s thought has been forgotten. Most of his contemporaries believed in the inheritance of acquired characteristics, so much so that they rarely felt and need to offer proof of it. The above summary of the four 1815 laws shows that the basic features of Lamarck’s evolutionary theory remained relatively unchanged from 1802.

Lamarck has been credited with introducing a branching family tree into evolutionary theory. It is true that in his major evolutionary works he often spoke of branching below the level of the “masses,” but he regarded these branchings as exceptions to the general rule of increasing structural complexity. In the Philosophie zoologique, Lamarck argued for a unilinear series of classes in each kingdom. In an addition at the end of the work, however, he presented a branching arrangement for animal classes in what is now a well-known diagram. It is significant that he was never able to integrate this new order with his evolutionary theory. The same discontinuity occurs in the 1815 “Introduction” in the body of the work he assume a linear series of the “masses,” and in a supplement he presents a diagram of branching classes (different from the 1809 version) which he labels as the presumed order of formation. These evolutionary trees were Lamarck’s acknowledgment of advances in comparative anatomy and natural classification. That he could not include them with his two-factor theory shows his strong lifelong commitment to a philosophical idea: the chain of being and its modified version of a hierarchical unilinear series of classes in the two kingdoms.

The above example indicates a very important aspect of Lamarck’s evolutionary theories. They were put forth by a philosopher-naturalist and not a positivist scientist. From his earliest scientific work, Lamarck was always more interest in the broad picture of nature and in general interrelations than in the details. While he did give scattered examples to support his theories, he was never systematic, always promising more evidence in a forthcoming work and never producing it. Lamarck felt that his theories were so obvious that they did not need extensive proof. In addition he was paranoid with respect to the French scientific community because of their attitudes toward his work in chemistry; he was convinced that he never could own over his enemies, so he did not try. With all his work in botany and invertebrate zoology, he would have had abundant examples if he had wanted them. He always separated his theories and his detailed classificatory work. Although he spent years carefully determining, describing, and classifying species, in his evolutionary views he maintained that species were almost irrelevant, exceptions to the general natural law of evolution.

Origins of Lamarck’s Theory . Lamarck was fifty-five when, in 1800, he made his first public statement of evolution. Until the late 1790’s he had believed in the fixity of species. Thus the question has always been why he changed his mind. Various answers have been and still are being put forth. They range from different influences from his own work to the particular influence of individuals. Among the former explanations, Lamarck’s work in geology, invertebrate classification, paleontology and the problem of extinction, and chemistry have all been seen as the crucial factor. Individuals who have been held to have exerted the decisive influence on Lamarck’s change of mind include Lacépéde, Cabains, Cuvier, and such earlier speculative thinkers as Buffon, Diderot, De Maillet, and Robinet. A study of the origins of Lamarck’s theory of evolution must be broadened beyond the issue of the fixity of species. He also changed his views on other issues. Not only should we look at the changes, but we should also look at the continuities. Many aspects of Lamarck’s evolutionary theory are found in his earlier works in different fields; some components of the theory, however, are new. Burkhardt, who recognizes the importance of continuities, has recently studied certain factors which he thinks were the immediate causes of Lamacrk’s evolutionary thought. In an article (1972) he presents a convincing argument to show that Lamarck changed his views on two important subjects (spontaneous generation and the mutability of species) between the spring of 1799 and the spring of 1800 and that in both cases the changes came about as a result of confronting the question of extinction. In the section on invertebrate paleontology, we summarized Burkhardt’s position. Lamacrk was faced with the extinction question in his study of fossil shells. Since an acceptance of extinction would have violated his view of nature, and since the migration theory was not really a satisfactory explanation, Lamarck was left with the choice that species change gradually with time.

Lamarck’s acceptance of the possibility of spontaneous generation came via a more circuitous route but one which was also related to the study of invertebrates and to the extinction question. Burkhardt suggests that Lamarck’s study of the invertebrates led him to a new definition of life. For Lamarck, the simplest organism demonstrated the minimum conditions necessary for life; lacking any specialized organs, they depended entirely on the movement of subtle fluids in the environment to maintain their organic movements. The next logical step was to move to a belief in spontaneous generation. If the subtle fluids could maintain this simple from of life, why could they not also create it when the circumstances were right? The extinction issue came in when Lamarck realized that these organisms were killed in bad whether. The only way he could account for their reappearance was by spontaneous generation. A belief in spontaneous generation was necessary for a theory of evolution, unless one wished to invoke a creator. Thus, according to Burkhardt, Lamarck’s changing positions on these two issues were the crucial events which led to his theory of evolution.

While accepting the changes described above, we should also look at some of the continuities in Lamarck’s thought. The continuities have been mentioned in each section of the article, but we will try to summarize them here. Lamarck had been interested in trying to develop a natural method of classification from the time of his earliest work in botany. Well before 1800, he had constructed a series of classes. In his theory of evolution, the natural method was the path nature had followed in producing the different groups of organisms. In Lamarck’s work prior to 1800, we see his stress on nature as a whole whose processes and interrelations are more important than the details. The chemistry provides the key to these connections and perhaps a model for understanding the realm and order of living organisms. Finally, Lamarck’s belief in the idea of progress may have prepared him for the application of such an idea to nature.

Lamarck’s Reputation . When Lamarck died in 1829, he left few followers; generally he was ignored. The official eulogy prepared by Cuvier for the Academy condemned Lamarck’s speculations and theories in all fields as being equally unacceptable faint praise; was offered for his contributions to biological classification. While he was ignored by his countrymen, he did receive some attention in England from the generation before Darwin. But it was really Darwin’s theory of evolution which ensured Lamarck’s fame. The question of the extent of Lamarck’s influence on Darwin is still debated. It was mainly Darwin’s enemies and detractors who revived Lamarck for a variety of reasons, ranging from scientific to religious to nationalistic (on the part of the French). Toward the end of the nineteenth century, a famous controversy developed between Darwinians and the so-called neo-Lamarckians; the latter used Lamarck’s views selectively and often changed many of them to suit their purposes. Neo-Lamarckism had strong proponents in France, Germany, England, America, and more recently in the Soviet Union. With the wide acceptance of Darwinism as modified by modern genetic theory, much of Lamarckism has died out, although some still apply it to seemingly purposive biological behavior.

Aside from his legacies and the battles fought in his name, Lamarck deserves an important place in the history of science. He made significant contributions in botany, invertebrate zoology and paleontology, and developed one of the first thoroughgoing theories of evolution .


I. Original Works. A more complete bibliography may be found in Landrieu (see below). Lamarck’s most important published works are Flore françoise, 3 vols . (Paris, 1779; 2nd ed ., 1795; 3rd ed ., 1805, in collaboration with A. P. de Candolle, 4 vols .; repr. of 3rd ed. with 1 vol. supp., 1815); Dictionnaire de botanique, vols. I-Ill and first half of IV of 8 vols . (Paris, 1783-1795) in Encyclopédie méthodique, C. J. Panckoucke, ed ., 193 vols . (Paris, 1782-1832); Illustration des genres, 3 vols . (Paris, 1791-1800), also in Encyclopédie méthodique; Recherches sur les causes des principaux fairs physiques, 2 vols . (Paris, 1794); Réfutation de la theorie pneumatique (Paris, 1796); Memoires physique et d’histoire naturelle (Paris, 1797); “Prodrome d’une nouvelle classification des coquilles,” in Memoires la Société d’histoire naturelle, I (Paris, 1799), 63-91; Annuaires meteorologiques, I1 vols . (Paris, 1800-1810); Système des animaux sans vertébres précédé du ’Discours d’ouverture du tours de zoologie de l’an VIII’ (Paris, an IX [1801]); Hydrogeologie (Paris, an X [1802]), English t rans. by A. V. Carozzi, Hydrogeology (Urbana, Ill ., 1964); Recherches sur l’organisation des corps vivans precede du ’Discours d’ouverture du tours de zoologie, l’an X’ (Paris, an X [1802]); Memoires sur les fossiles des environs de Paris (Paris, 1809), originally published as separate articles in Annales du Museum national d’histoire naturelle (Paris, 1802-1806); see Landrieu for vol. and page references; Introduction a la botanique, 2 vols . (Paris, 1803), part of Lamarck and B. de Mirbel, Histoire naturelle des Vegetaux, 15 vols . (Paris, 1803); Philosophie zoologique, 2 vols . (Paris, 1809; repr. Paris, 1830; New York, 1960), English trans ., Zoological Philosophy (London, 1914; repr. New York-London, 1963); Histoire naturelle des animaux sans vertebres, 7 vols . (Paris, 1815-1822); and Systeme analytique des connaissances positives de I’homme (Paris, 1820).

Posthumous works include “Discours d’ouverture des tours de zoologie donnes dans le Museum d’histoire naturelle, an VIII (1800), an X (1802), an XI (1803), et 1806,” A. Giard, ed ., in Bulletin sciemifrque de la France et de la Belgique, 40 (1906), 443-595; The Lamarck Manuscripts at Harvard, William Wheeler and Thomas Barbour, eds . (Cambridge, Mass ., 1933); “La biologic, texte inédit de Lamarck,” Pierre Grassé, ed ., in Revue scientifrque, 82 (1944), 267-276; and Inédits de Lamarck d’aprés les manuscrits conservés à la Bibliothéque centrale du Museum national d’histoire naturelle de Paris, Max Vachon, Georges Rousseau, and Yves Laissus, eds . (Paris, 1972).

Some unpub. MSS remain in the Muséum d’Histoire Naturelle’s collection; consult Max Vachon, Georges Rousseau, and Yves Laissus, “Liste compléte des manuscrits de Lamarck conservés à la Bibliothéque centrale du Museum national d’histoire naturelle de Paris,” in Bulletin Muséum national d’histoire naturelle, 2nd ser ., 40 (1969), 1093-1102 .

II. Secondary Literature. See Jean-Paul Aron, “Les circonstances et le plan de la nature chez Lamarck,” in Revue générate des sciences pures et appliquées, 64 (1957), 243-250; Franck Bourdier, “Esquisse d’une chronologie de la vie de Lamarck” (with the collaboration of Michel Orliac), unpub. memorandum, 3e section, école Pratique des Hauteétudes, 22 June 1971; Richard W. Burkhardt, Jr., “Lamarck, Evolution and the Politics of Science,” in Journal of the History of Biology, 3 (1970), 275–298; and “The Inspiration of Lamarck’s Belief in Evolution,” ibid., 5 (1972); Leslie J. Burlingame, “The Importance of Lamarck’s Chemistry for His Theories of Nature Evolution or Transformism,” in Actes du XIII Congrés international d’histoire des sciences, sect. IX A (Moscow); Dominique Clos, “Lamarck botaniste, sa contribution à la méthode dite naturelle,” in Mémoires de l’Académie des sciences, inscriptins et belles—lettres de Toulsous 9th ser., 8 (1896), 202–225; Georges Cuvier, “éloge de M. de Lamarck,” in Mémoire de l’Académie Royale des sciences de l’Institut de France, 2nd ser., 13 (1831), i—xxxo; Henri Daudin, Cuvier et Lamarck. Les classes zoologiques t l’idée de série anmale (1790–1830), 2 vols. (Paris, 1926), and De Linné à Jussieu. Méthode de la classification et idÉe de série en botanioque et en zoologie (1740–1790) (Paris, 1926), pp. 188–204; Charles C. Gillispie, “The Formation of Lamarck’s Evolutionary Theory,” in Archieves Internationales d’histoire des scinces, 9 (1956), 323–338; John c. Greene, The Death of Adam; Evolution and Its Impact on WEstern Thought (Ames, Iowa, 1959), pp. 160–171; Emile Guyéot, Les scines de la dive aux XVIIe et XVIIIe siécles (Paris, 1957), pp. 408–439; M. J. S. hodge, “Lamarck’s Sciences of Living Bodies,” in British Journal for the History of Science, 5 (1971), 323–352; Marcel Landrieu, Lamarck, le fondateur du transformisme, sa vie, son oeuvre (Paris, 1909), which is 21 of Mémoires de la Soiété Zoologique de France; Ernst Mayr, “Lamarck Revisited,” in Journal of the History of Biology, 5 (1972), 55–94; I. M Poliakov, Lamark i uchenia ob evolyutsii organicheskogo mir (“Lamarck and the Theory of the Evolution of the Oreganic Workd”) (Moscow, 1962); Georges Rousseau, “Lamarck et Darwin,” in Bulletin du Musèum national d’histoire naturelle, 5 (1969), 1029–1041; Joseph Schiller, ed., Colloque international Lamarck (Paris, 1971); and “Physiologie et classification dans l’oeuvre de Lamarck,” in Histoire t bilogie, 2 (1969), 35–57; J. S. Wilkie, “Buffon, Lamarck and Darwin: The Originality of Darwin’s Theory of Evolution,” in P. R. Bell, ed., Darwin’s Biological Work; Some Aspects Reconsidered (New York, 1959), pp. 262–307.

Highly recommended for background reading: Arthur O. Lovejoy, The Great Chain of Being (Cambridge, Mass., 1936); Jacques Roger, Les sciences de la vie dans la pensée française du XVIIIe siécle (Paris, 1963).

Leslie J. Burlingame

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