The Plastic Brain


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Has Lamarckism Evolved by Darwinian Selection?

I have had a long-standing interest in Lamarckism. Unlike Creationism, Lamarckism is a testable, scientific theory of evolution. Like Creationism, it has been rejected by the vast majority evolutionary biologists. However, I delight in the possibilities that arise from a competing theory. What if it were true? The thought of over-turning dogma, even something I love as much as Darwin’s theory of Natural Selection, makes me giddy.

And so, I have always had a soft spot for anything with a whiff of Lamarckism. Which I why I was surprised that I had not heard of Ted Steele before. This is especially galling as he hails from my home town of Adelaide.

From Steele’s Wikipedia entry:

Ted Steele developed the theory of reverse transcription from the somatic (body) cells to the germline (reproductive cells). This reverse transcription process enables characteristics or bodily changes acquired during a lifetime to be written back into the DNA and passed on to subsequent generations. This is what used to be known as neo-Lamarckism.[1] Steel’s theory provided the first mechanism to explain Lamarckian evolution: when successful somatic (body) cell changes occur due to environmental changes, copies of the copious new messenger-RNA that have been produced by the successful cells are picked up by harmless retroviruses acting as gene shuttles and transported across the tissue barrier – theWeismann Barrier – to the germline. Finally, the new genetic information is integrated into the DNA by a process involving reverse transcription. This process of writing or translating new information into the DNA provides the essential precursor to acquired changes being passed on to progeny; to the next generation, thereby demonstrating Lamarckian inheritance of acquired characters. Darwinian natural selection then goes to work on the progeny and subsequent generations: those fit for survival do so and those not fit die out. This recombination of Darwin and Lamarck by Steele has been described as meta-Lamarckism[2].

This would suggest that Darwinian evolution has selected for genomes that allow this sort of process to go on, and that it may, in fact, be advantageous.

I’m happy to concede that Lamarck didn’t work out the theory of evolution, but neither did Darwin. Although I suspect Darwin’s natural selection of inherited variation will remain the core of evolutionary theory, it’s fun to see a bit of Lamarckism thrown into the mix. Who knows what else is yet to be added?


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Anti-Darwin Logic

I am having a fine old time whetting my teeth on the anti-Darwinism classic “The Neck of the Giraffe: or Where Darwin Went Wrong” by Francis Hitching.

My favourite bit of logic so far centres on the paradox of transitional species.

Part 1: If man has evolved from monkeys, where is the transition species? Why are there no half-monkey, half-man species around today? -> If evolution worked by Darwinian mechanisms, there would be extant transition species

Part 2: If so-called transition species are alive today, then they can’t be transitions after all, since they have “obstinately refus[ed] to evolve” between the time that speciation occurred until now. -> If the are extant transition species, then evolution cannot work by Darwinian mechanisms

There is a slight logical contradiction between Part 1 and Part 2. Can you find it?


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The Elucidating Adventures of Charles and Harriet

Charles: Hello young tortoise. I am going to become rather famous, you know. I shall pen the seminal work On the Origin of Species by Means of Natural Selection.
Harriet: That is rather impressive. But I shall outlive you by many years, and I shall go on the meet Steve Irwin.
Charles: Touché.

Charles: Would you like to go on an amazing voyage with me, young lad?
Harriet: I thought you’d never ask. Only, I’m not a..oh, well, never mind.