Jean-Baptiste Lamarck. Dictionnaire encyclopédique methodique: Planches de botanique. Paris: 1785.  Anthony R. Michaelis Collection, gift of J. Philip Gibbs, Jr. 





Although Erasmus Darwin was one of the first to write about evolution in a serious way, the more influential and systematic of the theory’s early proponents was the French naturalist Jean-Baptiste Lamarck (1744-1829). Lamarck used the metaphor of a ladder of progress to explain the tendency of organisms to become more complex over time, primarily through environmental influences which cause animals to adapt to the specific locations in which they live. According to Lamarck’s theory, characteristics change through a use and disuse model. The use of an organ by an animal will cause it to develop and enlarge in subsequent generations, whereas disuse will cause it to weaken and diminish until it finally disappears altogether. Charles Darwin discusses Lamarck’s work in the introduction to Origin of Species and praises him as a “justly-celebrated naturalist”, but it is clear that he finds the use/disuse theory unconvincing: “To this latter agency he seems to attribute all the beautiful adaptations in nature; - such as the long neck of the giraffe for browsing on the branches of trees.”   Darwin also disagreed with Lamarck’s implication that the changes in species were due to positive progression, which implied a divine presence. 

The volume shown in Darwin’s Ancestors is a section of the Encyclopédie méthodique entitled Planches de botanique. Lamarck was given the task of writing the botanical section of the encyclopedia, which was a continuation of the original Encyclopédie by Diderot. The first part of Lamarck’s section was published in 1783, with subsequent sections being introduced through 1788. The volumes were the product of Lamarck’s work as keeper of the herbarium at the Jardin du Roi (later Jardin des Plantes), a botanical garden in Paris. The concern with botanical taxonomy which is present in the Planches de botanique contributed to Lamarck’s later thoughts on the evolution of species.


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