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Evolution Explained Part 12 – Lamarck

This is Part 12 of a series of approximately sixty posts that outline evidence, support, and explanations for evolution. Receive updates and notification of all posts from dennismitton.com by selecting the follow button on the sidebar of any page. Thanks!

 

Copyright Dennis Mitton


Jean-Baptiste Lamarck

Lamarck EvolutionThe stage is set for a discussion about the development of evolutionary ideas. I’ve written about the philosophy of science, scientific theories, and uniformitarianism.

There were rumblings in dark corners and back hallways that maybe the Church had it wrong. Hutton, the Scottish geologist, was largely responsible for the rumor and paid a price. By the late 1700’s, it was figured out that the earth isn’t the center of the universe. Some thought the universe to be unimaginably old. And while catastrophism is useful to describe local events, geology trudges forward with repeated and slow cycles. And what about all these fossils? How to explain them?

Enter Frenchman Jean‑Baptiste Lamarck.

Lamarck was born in the middle of the eighteenth century. He lived in Paris and started out in the family career as a soldier. Wounded as a young man, he was rewarded with a state stipend small enough to force him into a new career. He studied medicine for four years with little interest and then went to work as a botanist. He took a low paying position at the Royal Botanical Garden and then, after the king and queen lost their heads on the chopping block, Lamarck was appointed to a professorship at the newly named National Museum of Natural History. While there, and with the whole of nature preserved before him, he began to codify his ideas about the development of new traits.

Rejecting catastrophism (for which Couvier never forgave him) he saw all life forms represented in a straight vertical line moving increasingly toward ‘perfection’. Single-celled life rested on the bottom with all other organisms rising spontaneously and continuously as the line inched toward humankind, the pinnacle of creation. Each organism took their seat on the line per their level of complexity and perfection, loosely defined by comparison to man. Each organism experienced a continual push, driven by felt needs, to achieve perfection. This tacit inner drive was a god-given life force within all living things that pushed them toward betterment. Without an understanding of mechanisms of descent and change this idea fit in well with current philosophies. Culture – especially French culture – had left behind medieval ideas about the roles of kings and church and peasants. New ideas heralded purpose and betterment through science and education. Men strove to build better societies. They explored better government (look at what those ‘Americans’ across the Atlantic are doing…) Educated thinkers believed that each man can and should strive to improve himself. It’s no surprise that scientists in this nascent field believed that an innate drive toward perfection existed in all organisms.

The Inheritance of Acquired Traits

Lamarck saw this drive expressed in two ways. The first mechanism is the inheritance of acquired traits. Lamarck famously – or infamously – argued that the blacksmith builds strong muscles as he plies his trade all day. That strength is incorporated into his seed and passed to his children. The giraffe, always striving for food in the upper reaches of the tree, stretches its neck and, in so doing, passes that stretched neck to its offspring. Note that Lamarck saw no room for speciation. He believed that ‘nature’ spontaneously erupts with new species and that each individual acquired traits passed on to offspring. He largely rejected the concept of species altogether viewing it as an unnecessary and arbitrary abstraction. Instead, he viewed each individual of every organism as a self-contained entity striving toward greater perfection.

What is most interesting about the ideas – later shown to be wrong – are that, for the first time, scientists were looking at natural mechanisms without the need for a creator. While true that many of these scientists were Christians or deists, their god was at best a remote watchmaker unencumbered with thoughts about managing this little part of the universe. Acquired Traits was also an important step in our understanding of nature as it expressed a change in response to environmental pressures. The elephant’s trunk elongates in response to more and better access to food and water. It’s not quite Darwin’s natural selection but it gets close.

Lamarck Evolution
Lamarck’s Giraffes stretching their necks…

The other concept Lamarck is remembered for is his codification of use and disuse. He argued that if a trait or characteristic is not used, it would, over time, fade away. In the same way, like the blacksmith’s biceps or the crab’s claw, anything that grew in size or importance would also pass on to the offspring. He was close but with no understanding of genetic mechanisms, he couldn’t know that traits become more prominent within a population through selection.

Largely ridiculed since the development of modern evolutionary theory, Lamarck was a visionary and a true scientist. He worked hard to shed the strangling cloak of religious thought and sought natural answers for what he saw in the world around him. Though his ideas were finally proved to be incorrect he should be considered one of the first evolutionists believing in change as a response to environmental pressures.

New Lamarckianism?

There is evidence that Lamarck might not have been all wet. While the genetic basis for evolution and reproduction are well understood, we see that – at least in mice – certain events or environments place a fork in the road for a mother’s offspring. The conditions can effectively change gene expression in her pups. The mechanisms aren’t clearly understood and this kind of computer programming IF→THEN statement doesn’t exactly qualify as a Lamarckian mechanism but it’s certainly interesting. No doubt there will be much more to come.

See here at the MIT Technology Review
Jerry Coyne says Nae to epigenetics here at Why Evolution Is True
Lamarck at Wiki.


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Published inEvolution Explained

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