Lamarck, Jean-Baptiste de Monet (b. Aug. 1, 1744, Bazentin-le-Petit, Picardy, France--d. Dec. 18, 1829, Paris) was the pioneer French biologist who is best known for his idea that acquired traits are inheritable, an idea known as Lamarckism, which is controverted by Darwinian theory.

Lamarck was the youngest of 11 children of a baron and lieutenant of infantry. Intended for the priesthood, he was sent to a Jesuit school at Amiens, but after his father died he took the opportunity to enlist in an infantry regiment, serving several years (1761-68). He became interested in plants while stationed on the Riviera and, following his resignation from the army, embarked upon the study first of medicine and then of botany. He soon devoted himself entirely to botany under the French botanist Bernard de Jussieu at the Jardin du Roi (the royal botanical gardens) in Paris.

Drawing on nine years of field study and collecting, Lamarck published a three-volume flora of France in 1778. Botany had become universally popular, and a wide public greeted his Flore frangaise ("French Flora") as a useful manual of identification. It did not adhere slavishly to the methods of the Swedish botanist Carolus Linnaeus and won for Lamarck appointment to the Academy of Sciences, which at that time was restricted to 42 members. Count Georges de Buffon, the leading naturalist of the day, engaged him as tutor to his son during two years of travel in central Europe visiting botanical gardens and other learned institutions. He devoted the years following to voluminous botanical writings for the Encyclopidie mithodique ("Methodic Encyclopaedia"), successor of the famous Encyclopidie founded by Denis Diderot, and to working as curator of the royal herbarium.

The revolution of 1789 was devoted to remaking institutions of intellect as well as of politics, and so the royal collection of natural history was discontinued. Lamarck addressed a memoir to the National Assembly condemning the random cabinets for display of curiosities built up by well-meaning amateurs and urged instead that collections be applied to the progress of science through the establishment of a great museum of natural history. Within such a collection objects "ought to be arranged in methodical or properly systematic order," not for display at random: each division of nature (animal, vegetable, and mineral) should be subdivided by classes, and those in turn by orders, and so to genera, with a written catalogue that would be the basis for systematic knowledge. Lamarck was one of the originators of the modern concept of the museum collection, an array of objects whose arrangement constitutes a classification under institutional sponsorship, maintained and kept up to date by knowledgeable specialists. When the Jardin des Plantes (National Museum of Natural History) was founded in 1793, Lamarck was placed in charge of the invertebrates, of which he had already made an important collection. He seems to have been the first to relate fossils to the living organisms to which they corresponded most closely.

By the end of the 18th century, enough had been learned in the sciences of chemistry and physiology to persuade the most acute inquirers that new understandings might be attained through patient search for clues to fundamental relationships. Lamarck had been satisfied with and indeed excited by the looser, less critical notions of natural rhythm and the sense of cosmic unities entertained by 18th-century writers. To Lamarck it seemed that the new chemistry of Antoine Lavoisier led away from grand facts into a labyrinth of details. Lamarck feared that science would cease to be a coherent system whereby all men might understand the world and their place in it, becoming instead the confined domain of a few specialists. So he conceived a plan for a series of treatises, elaborating a unified view of physical processes, chemistry, geology, climate, and life.

The first of these was a two-volume speculative treatment of matter and energy, Recherches sur les causes des principaux faits physiques, et particulihrement sur celles de la combustion (1794; "Research on the Causes of Principal Physical Facts, and Particularly on Those of Combustion"), followed in 1796 by Rifutation de la thiorie pneumatique, ou de la nouvelle doctrine des chimistes modernes ("Refutation of the Pneumatic Theory, or of the New Doctrine of Modern Chemists"), in which he opposed his own theory of combustion to the views of Lavoisier and Count Antoine de Fourcroy. Neither of Lamarck's works was calculated to appeal to the mood of caution then coming to govern most serious scientific work, and Lamarck did not know how to dramatize his views for a wider public.

His Hydrogiologie (1802; Hydrogeology) offered a history of the earth interpreted as a series of inundations by a global sea, each accompanied by organic deposits building up the continents. Among the insights that were highly advanced for his day was Lamarck's recognition that the type of fossil occurring in a deposit would permit inferences as to whether the deposit had been built up as deep-marine sediments or as coastal deposits. The book also revealed an extraordinary perception of the vastness of geologic time. "Time is insignificant and never a difficulty for Nature. It is always at her disposal and represents an unlimited power with which she accomplishes her greatest and smallest tasks." This treatise was also neglected, to Lamarck's deepening sorrow. Increasingly, science was being conducted through networks of mutual criticism in which evidence and data were employed to secure wide acceptance of essential facts before general theories were attempted. Scorning these procedures, Lamarck was transformed into a scientific outcast and gradually became an embittered solitary.

Systematic biology of the invertebrates. In 1800 he announced a revision of the classification of lower animals that had been left in a confused state by Linnaeus. He was able to penetrate superficial resemblances in form, as between certain worms and mollusks, through discriminating analysis of the functions and complexity of essential organs. This work he placed on an empirical foundation, "having at my disposal the magnificent collections of the Museum and another fairly rich, which I have myself made in the course of nearly thirty years' work." Published as Systhme des animaux sans verthbres, ou table giniral des classes ("System of Invertebrate Animals, or General Table of Classes") in 1801, Lamarck's first major work on the invertebrates reflected current research, most notably the anatomical studies of Cuvier, and established the basic arrangement for these animals that served as a guide to inquiry throughout the 19th century and is still largely accepted. These systematic studies of invertebrates were climaxed by the publication of his life's work, Histoire naturelle des animaux sans verthbres ("Natural History of Invertebrate Animals"), from 1815 to 1822, a complete vindication of his proposal to establish museum collections as the basis for revisionary work in systematic biology.

Lamarck imagined a vast sequence of life forms extending like a series of staircases from the simplest to the most complex. Impelled by "excitations" and "subtle and ever-moving fluids," the organs of animals became more complex and took their place on successively higher levels. This was the summary view of the relationship between physical energy and the overall organization of life set forth in Recherches sur l'organisation des corps vivants (1802; "Research on the Organization of Living Bodies") and the Philosophie zoologique (1809; Zoological Philosophy). In the latter work he stated two "laws" that he held to govern the ascent of life to higher stages: first, that organs are improved with repeated use and weakened by disuse; second, that such environmentally determined acquisitions or losses of organs "are preserved by reproduction to the new individuals which arise." Thus, in a celebrated example, the forelegs and neck of giraffes have become lengthened through their habit of browsing. With the publication of Charles Darwin's Origin of Species 50 years later, these views of Lamarck became the centre of interest and controversy. Lamarckism was discredited by most geneticists after the 1930s, except in the Soviet Union, where, as Lysenkoism, it dominated Soviet genetics until the 1960s. As originally formulated, however, Lamarckism was part of an elaborate surmise about processes for whose operation Lamarck had no direct evidence. To apply excerpts from so general a course of speculation to questions made much more precise through the application of Darwinian theory a century or more later--especially within the field of genetics, of which Lamarck had no conception--necessarily entails radical alterations of his meaning. From a lifelong, direct exposure to plants and animals Lamarck gained an intuitive sense of the dynamic quality of life, the close interdependence of physical and vital processes upon which the modern science of biology rests. Indeed Lamarck was the first to use the word biology, in 1802. But in the history of that science he may best be considered a forerunner rather than a founder, except in the systematic biology of the invertebrates, for which he established not only the best procedures of inquiry but also the kind of institution within which these inquiries have since been most successfully pursued.

Lamarck died blind and in poverty.

Excerpt from the Encyclopedia Britannica without permission.