Lamarckianism

ALSO KNOWN AS: Lamarkism

SIGNIFICANCE: Although some aspects of Lamarckianism have been discredited, the basic premises of nineteenth century French biologist Jean-Baptiste Lamarck’s philosophy have become widely accepted tenets of evolutionary theory. Lamarckianism became intellectually suspect following fraudulent claims by the Soviet scientist Trofim Lysenko that he could manipulate the heredity of plants by changing their environment; by the 1990’s, however, scientists had become more willing to acknowledge the influence of Lamarckianism in evolutionary biology.

Lamarckianism Defined

The term “Lamarckianism” has for many years been associated with intellectually disreputable ideas in evolutionary biology. Originally formulated by the early nineteenth century French scientist Jean-Baptiste-Pierre-Antoine de Monet, chevalier de Lamarck (1744-1829), Lamarckianism had two components that were often misinterpreted by scholars and scientists. The first was the transformist theory that animals gradually changed over time in response to their perceived needs. Many critics interpreted this to mean that species could adapt by wanting to change—in other words, that giraffes gradually evolved to have long necks because they wanted to reach the leaves higher in the trees or that pelicans developed pouched beaks because they wanted to carry more fish. Where Lamarck had suggested only that form followed function—for example, that birds that consistently relied on seeds for food gradually transformed to have beaks that worked best for eating seeds—critics saw the suggestion of active intent or desire.

The second component of Lamarckianism, that changes in one generation of a species could be passed on to the next, also led to misinterpretations and abuses of his ideas. In the most egregious cases, researchers in the late nineteenth and early twentieth centuries claimed that deliberate mutilations of animals could cause changes in succeeding generations—for example, they believed that if they cut the tails off a population of mice, succeeding generations would be born without tails. During the twentieth century, the Soviet agronomist Trofim Lysenko claimed to have achieved similar results in plants. Such claims have been thoroughly disproved.

Who Was Lamarck?

Such gross distortions of his natural philosophy would probably have appalled Lamarck. Essentially an eighteenth century intellectual, Lamarck was one of the last scientists who saw himself as a natural philosopher. He was born August 1, 1744, in Picardy, and as the youngest of eleven children was destined originally for the church. The death of his father in 1759 freed Lamarck to leave the seminary and enlist in the military, but an injury forced him to resign his commission in 1768. He sampled a variety of possible vocations before deciding to pursue a career in science.

His early scientific work was in botany. He devised a system of classification of plants and in 1778 published a guide to French flowers. In 1779, at the age of thirty-five, Lamarck was elected to the Académie des Sciences. Renowned naturalist Georges-Louis Leclerc, comte de Buffon, obtained a commission for Lamarck to travel in Europe as a botanist of the king. In 1789, Lamarck obtained a position at the Jardin du Roi as keeper of the herbarium. When the garden was reorganized as the Museum National d’Histoire Naturelle in 1794, twelve professorships were created; Lamarck became a professor of what would now be called invertebrate zoology.

Lamarck demonstrated through his lectures and published works that he modeled his career on that of his mentor, Buffon. He frequently went beyond the strictly technical aspects of natural science to discuss philosophical issues, and he was not afraid to use empirical data as a basis for hypothesizing. Thus, he often speculated freely on the of species. Philosophie zoologique (Zoological Philosophy, 1914), now considered his major published work, was issued in two volumes in 1809. In it, Lamarck elaborated upon his theories concerning the evolution of species through adaptation to changes in their environments. An essentially philosophical work, Zoological Philosophy is now remembered primarily for Lamarck’s two laws:

First Law: In every animal which has not passed the limit of its development, a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ and gives it a power proportional to the length of time it has been so used; while the permanent disuse of any organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappears.

These two tenets constitute the heart of Lamarckianism.

During his lifetime, Lamarck’s many books were widely read and discussed, particularly Zoological Philosophy. It is true Lamarck’s ideas on the progression of life from simple forms to more complex forms in a great chain of being met with opposition, but that opposition was not universal. He was not the only “transformist” active in early nineteenth century science, and his influence extended beyond Paris. Whether or not Lamarck directly influenced Charles Darwin is a matter of debate, but it is known that geologist Charles Lyell read Lamarck, and Lyell in turn influenced Darwin.

Lamarckianism’s fall into disrepute following Lamarck’s death was prompted by social and political factors as well as scientific criteria. By the 1970’s, after a century and a half of denigration, Lamarckianism began creeping back into evolutionary theory and scientific discourse. Researchers in microbiology have described processes that have been openly described as Lamarckian, while other scholars began to recognize that Lamarck’s ideas did indeed serve as an important influence in developing theories about the influence of environment on both plants and animals.

Key terms

• acquired characteristica change in an organism brought about by its interaction with its environment
• Lysenkoisma theory of transformation that denied the existence of genes
• transformist theory of evolutiona nineteenth century theory that animals gradually changed over time in response to their perceived needs

Bibliography

Burkhardt, Richard W., Jr. The Spirit of System: Lamarck and Evolutionary Biology, Now with “Lamarck in 1995.” Cambridge, Mass.: Harvard University Press, 1995.

Burkhardt, Richard W. "Myth 8 - That Darwin Rejected Lamarck's Ideas of Use and Disuse and of the Inheritance of Acquired Traits." Cambridge University Press, 30 May 2024, www.cambridge.org/core/books/abs/darwin-mythology/that-darwin-rejected-lamarcks-ideas-of-use-and-disuse-and-of-the-inheritance-of-acquired-traits/6CE6AD684EED065ECA7B4E88F2FB6B21. Accessed 5 Sept. 2024.

Dempster, W. J. The Illustrious Hunter and the Darwins. Lewes, England: Book Guild, 2005.

Fine, Paul E. M. “Lamarckian Ironies in Contemporary Biology.” Lancet1, no. 8127 (June 2, 1979): 1181-1182.

Lamarck, Jean-Baptiste de Monet de. Lamarck’s Open Mind: The Lectures. Gold Beach, Oreg.: High Sierra Books, 2004.

‗‗‗‗‗‗‗. Zoological Philosophy: An Exposition with Regard to the Natural History of Animals.

Lanham, Url. Origins of Modern Biology. New York: Columbia University Press, 1971.

Persell, Stuart Michael. Neo-Lamarckism and the Evolution Controversy in France, 1870-1920.

Steele, Edward J., Robyn A. Lindley, and Robert V. Blanden. Lamarck’s Signature: How Retrogenes Are Changing Darwin’s Natural Selection Paradigm. Reading, Mass.: Perseus Books, 1998.