Jean-Baptiste Lamarck

Jean-Baptiste Lamarck (1744-1829), French botanist and invertebrate zoologist, who formulated one of the earliest theories of evolution.

Lamarck was born in Bazentin-le-Petit, the 11th child of a minor noble. The family was not wealthy, and Lamarck’s elder brothers followed their father into military careers, but for financial reasons he was sent to a Jesuit school in Amiens, destined for the Church. After his father’s death in 1759, Lamarck joined the army. Aside from active duty he began collecting plants and developed an interest in botany. In 1768 he was forced to leave the army after a prank among fellow officers left him requiring surgery to his neck. While recovering in Paris, he studied medicine, also the way to a life in natural science. The pursuit of natural science, in particular collecting specimens for display in a cabinet, and discussion at the salons, appealed to many of the intelligentsia and affluent classes. In such an environment Lamarck continued his botanical studies and developed an interest in meteorology, chemistry, and geology (particularly fossil shells), hoping for a professional scientific career.

Under the patronage of the naturalist Georges Louis Leclerc Buffon, who secured the necessary government funding, Lamarck published Flore François (1779; “Plants of France”). This book provided an easy reference guide for amateur botanists, but also took issue with some of the problems of the artificial classification schemes of Carolus Linnaeus. The success of the book, and his friendship with Buffon, led to Lamarck’s election to the Academy of Sciences. He became an associate botanist in 1783, but he conducted his most significant research after beginning to work at the Jardin du Roi (King's Garden) in 1788. During the French Revolution, when the garden was reorganized (1793), Lamarck's ideas helped to frame the structure of the new Museum of Natural History. Ironically, under the new system Lamarck was obliged to give up botany and became professor of insects and worms, a division he named “invertebrate zoology”. This proved a pivotal appointment. Lamarck’s later research on the “degenerate” or “imperfect” creatures, that is, those equipped with the minimum required to sustain life, and located at the lower end of the theoretical Échelle des êtres (chain of being), was key to his evolutionary theories.

At the turn of the 19th century, natural science was moving towards independent disciplines and away from the grand theories made popular by writers such as Buffon in the 18th century. Thus Lamarck's contributions to meteorology, botany, chemistry, geology, palaeontology, and biology (a word he coined in 1802), which he sought to unite in a comprehensive explanatory system of “terrestrial physics”, were received in silence. On the contrary, his impressive seven-volume work, Histoire Naturelle des Animaux sans Vertèbres (1815-1822; “Natural History of Animals without Backbones”) met with praise. Despite the painstaking nature of this work, it is Lamarck’s theoretical observations on evolution, referred to in the early 19th century as transformism or transmutation, which have had a lasting impact.

Like his contemporaries such as Georges Cuvier (who later changed his mind) and Geoffroy Saint-Hilaire, Lamarck believed that animals were arranged on the continuous chain of being or scala naturae (scale of nature). Man, the most perfect creation, was at the head of the chain, followed by the mammals, birds, reptiles, and fish to the lowliest creatures. Moving downward, each animal became progressively more degenerate with respect to man. However, as a result of his work with invertebrates, Lamarck reversed his conception of the chain, reading it from the bottom to the top. According to Lamarck, once life arose (by “direct” or “spontaneous” generation), the arrangement of all subsequent forms of life resulted from time, and the operation of environment on the organization of organic beings. From the simplest forms of life, more complex forms emerged. Lamarck did not believe in the extinction of species, or indeed that forces in nature other than those in evidence in his own time had shaped the Earth. Without extinction, he argued that mutability of species was essential to account for the fossil record.

These ideas were initially presented in Lamarck's major theoretical work, Philosophie Zoologique (1809; “Zoological Philosophy”). He continued their elaboration for the rest of his life. The final treatment of his hypothesis was included in the multi-volume work on invertebrates. Lamarck elucidated the biological laws he believed controlled transmutation and led to the progressive impulse to ascend the chain of being: environmental influence on organ development and change in body structure based on use and disuse of parts. Most famously the “inheritance of acquired characteristics” allowed the diversification of animals to meet the changing needs of their environment; for example, the length of a giraffe’s legs and neck being the result of subsequent generations stretching to reach ever-higher leaves. Lamarck's ideas suffered from his poor writing style and unfocused arguments. His theory of transmutation suffered at the hands of Cuvier, who championed his own ideas of fixed species from a more powerful scientific and political position. Cuvier disparaged Lamarck’s suggestion that animals consciously willed their bodies to change over time; in effect this was a misreading by Cuvier. Lamarck died blind and in poverty with little scientific recognition of his ideas. In the second half of the 19th century, after Darwin had made the concept of evolution by natural selection part of mainstream science, many scientists reconsidered Lamarck’s ideas on the inheritance of acquired characteristics. His name became attached to any theory of inheritance in which the environment plays an active role—the so-called theories of soft inheritance. Lamarckism continued in an isolated way in the 20th century, most notably in Russian genetics under T. D. Lysenko.