Oct 26 2010

Despised Theories (1): Lamarkism

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ean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (1744 – 1829) was a French naturalist and an early proponent of the idea that evolution occurred and proceeded in accordance with natural laws. Lamarck is however remembered today mainly in connection with a discredited theory of heredity, the inheritance of acquired traits (“Lamarckism”) He was also one of the first to use the term “biology” in its modern sense.

The Chevalier.

After serving in the army, Lamarck became interested in natural history and writing a multi-volume flora of France. After years spent working on plants and believing that species were essentially unchanging he began to investigate invertebrates (another term he coined). Working with mollusks he grew convinced that transmutation or change in the nature of a species did occur over time and set out to develop an explanation, which he outlined in his 1809 work, Philosophie Zoologique. In this work he encapsulated his theories into two “laws”:

  • In every animal that 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.
  • All the acquisitions or losses wrought by nature on individuals, through the influence of the environment through the influence of the predominant use or permanent disuse of any organ are preserved by reproduction to the new.

Lamarck saw spontaneous generation as ongoing, with the simple organisms thus created being transmuted over time and becoming more complex and closer to some notional idea of perfection.

Like Hans Driesch’s work a century later, Lamarck believed in a teleological (goal-oriented) process where organisms became more perfect as they evolved. Teleological explorations try to interpret the purpose, or “end reason” behind things. It is most often contrasted with metaphysical naturalism or physicalism, the position that everything that exists is no more significant than the sum total of its physical properties.

Most modern geneticists reject most teleological implications by nature, although as the geneticist J.B.S Haldane (1892-1964) observed:

Teleology is like a mistress to a biologist: he cannot live without her but he’s unwilling to be seen with her in public.

Lamarck’s defenders believe he is unfairly vilified today. They note that he believed in organic evolution at a time when there was no theoretical framework to explain evolution. He also argued that function precedes form, an issue of some contention among evolutionary theorists at the time.

Darwin not only praised Lamarck in the third edition of The Origin of Species for supporting the concept of evolution and bringing it to the attention of others, but also accepted the idea of use and disuse, and developed his theory of pangenesis partially to explain its apparent occurrence. Like many of his contemporaries Darwin believed in the inheritance of acquired characteristics simply because before the discovery of the cellular mechanisms for genetic transmission the idea was the most plausible.

Nowadays, the idea of passing on to offspring characteristics that were acquired during an organism’s lifetime is called Lamarckism. Lamarckism would go on to a long life in thousands of high school biology classes, serving as an example of “what not to do.” This view was, until very recently, thought to be inconsistent with modern genetics, certainly until the discovery of epigenetic (post-genomic) inheritance.

3 responses so far

3 Responses to “Despised Theories (1): Lamarkism”

  1. Andrea says:

    Your passion for the redemption of Lamarck is clearly evident.

    You already know how medicine advances, one death at a time, so it may take awhile for science to take him seriously once again.

  2. Jerome says:

    Interestingly, on my biology exam tomorrow, I am expected to identify Lamarckism as “what not to do.” It was interesting learning about it in class, though I am sure that if it were a genetics class, we would have gone more into the subtleties of his theory and its application today.

  3. [...] leave a role for alternate theories of variation, such as those proposed by the French naturalist Jean-Baptiste Lamarck (1744-1829). Lamarck postulated that an organism could pass on characteristics that it acquired [...]

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