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A Year: Day to Day Men: 1st of August, Solar Year 2018

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August 1, 1744 was the birthdate of French naturalist Jean-Baptiste Chevalier de Lamarck.

Jean-Baptiste Lamarck began as an essentialist who believed species were unchanging; however, after studying the mollusks of the Paris Basin, he grew convinced that transmutation or change in the nature of a species occurred over time. He set out to develop an explanation. On May 11th of 1800, Lamarck  presented a lecture at the National History Museum in which he first outlined his newly developing ideas about evolution.

Although Lamarck was not the first thinker to advocate organic evolution, he was the first to develop a truly coherent evolutionary theory. He stressed two main themes in his biological work: The first was that the environment gives rise to changes in animals. He cited examples of blindness in moles, the presence of teeth in mammals and the absence of teeth in birds as evidence of this principle. The second principle was that life was structured in an orderly manner and that many different parts of all bodies make it possible for the organic movements of animals.

Lamarck employed several mechanisms as drivers of evolution, drawn from the common knowledge of his day and from his own belief in chemistry. He used these mechanisms to explain the two forces he saw as comprising evolution; a force driving animals from simple to complex forms, and a force adapting animals to their local environments and differentiating them from each other. He believed that these forces must be explained as a necessary consequence of basic physical principles, favoring a materialistic attitude toward biology.

Lamarck argued that organisms thus moved from simple to complex in a steady, predictable way. The second component of Lamarck’s theory of evolution was the adaption of organisms to their environment. This could move organisms upward from the ladder of progress into new and distinct forms with local adaptations. It could also drive organisms into evolutionary blind alleys, where the organism became so finely adapted that no further change could occur. Lamarck argued that this adaptive force was powered by the interaction of organisms with their environment, by the use and disuse of certain characteristics.

Lamarck constructed one of the first theoretical frameworks of organic evolution. While this theory was generally rejected during his lifetime, Stephen Jay Gould, paleontologist and evolutionary biologist, argues that Lamarck was the “primary evolutionary theorist”, in that his ideas, and the way in which he structured his theory, set the tone for much of the subsequent thinking in evolutionary biology, through to the present day.

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