



Jean-Baptiste Lamarck (1744–1829) was one of the most prolific scientific figures of the 18th century, prior to Darwin. After being awarded for bravery in the Pomeranian War (1757 – 62), Lamarck developed a passion for science, in particular botany. Later he became the Chair of Botany at the Jardin des Plantes in Paris and a Professor of Zoology. Lamarck discovered and named over 3,000 species and has had over 200 species named after him! So it's clear that Lamarck was massively influential for his time and has a strong legacy, but why am I writing about him today?

Darwin was not the first biologist to contemplate evolution. Lamarck was the first person to create a fully-developed theory for the transformation of species and how an organism can adapt to an environment. Although Lamarck provided many examples for his theory, the most famous example is how the giraffe developed a long neck. Lamarck proposed that ancestral giraffes ate leaves from the lower branches of trees, however, the giraffes would continually stretch their necks to reach leaves higher up the trees. This would cause the giraffes necks to increase in length and this trait would be passed onto offspring through the inheritance of acquired characteristics. This theory was accepted throughout the 19th Century and well into the 20th Century, however, it was effectively dismissed by a series of experiments conducted by August Weisman. In his experiments, Weisman cut off the tails of mice in five subsequent generations and in approximately a thousand offspring no tail shortening was observed. Darwin's theory of evolution and Mendelian inheritance have substantially shaped how evolution is viewed today.





In modern science, the idea of a trait changing in response to the environment could be inherited is not so far-fetched in light of developments seen in the field of epigenetics. Epigenetics is the study of changes in organisms caused by modification of gene expression rather than the alteration of the genetic code itself.





The easiest way, I find, to think about epigenetics is - imagine a row of light switches, but the light switches are switched on and the room is very bright. In fact, the room is too bright for you so you turn off some of the light switches and the room becomes less bright and you feel more comfortable. In epigenetics, the row of light switches is DNA, the switches are the genes and the light is the physical trait. When the switch is on, the gene is expressed and the trait is present. Now for a real example, the arctic fox. In the winter and autumn months, the arctic fox has a white coat for camouflage purposes in its snowy environment, while, in the summer and spring it has a darker coat due to the lack of snow. Here, the arctic fox’s coat colour is the light in our earlier scenario, and the presence of snow is turning the switch on or off. Here changes in gene expression result from environmental factors, i.e the presence of snow. Epigenetic changes could provide increased genetic variation within a population, which would be advantageous in fluctuating environments.

Whether and to what extent epigenetic processes affect evolution is a matter of debate. The reason I wanted to discuss Lamarck was because his story inspires me. You are probably reading this and thinking "What? How does this whistle-stop tour of evolutionary history inspire someone!?". Lamarck did something that I can only aspire too, he had an original thought (the inheritance of acquired characteristics). Although it was debunked quite effectively, due to advances in science, aspects of his ideas resonate in evolutionary and biological processes studied today. I personally see Lamarck's story as not one of failure but one of attitude. Always question the world around you, be curious and most of all don't give up. To even fathom a theory of inheritance in the 18th Century, before Medilian genetics was common knowledge, is truly ground-breaking and that's why Jean-Baptise Lamarck is still being talked about today!

Let me know in the comments below what you think of Jean-Baptiste Lamarck's story. Does it inspire you? Are there any other scientists who have inspired you as Lamarck inspired me?





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Further Reading

Bowler, Peter J. Evolution: the history of an idea. Univ of California Press, 1989.

Mayr, Ernst. The growth of biological thought: Diversity, evolution, and inheritance. Harvard University Press, 1982.

Moazed, Danesh. "Mechanisms for the inheritance of chromatin states." Cell 146.4 (2011): 510-518.

Ptashne, Mark. "On the use of the word ‘epigenetic’." Current Biology 17.7 (2007): R233-R236.

Youngson, Neil A., and Emma Whitelaw. "Transgenerational epigenetic effects." Annu. Rev. Genomics Hum. Genet. 9 (2008): 233-257.