Happy birthday, Lamarck

Happy birthday, Jean-Baptiste! On this day, August 1, in 1744 Jean-Baptiste Pierre Antoine de Monet, the Chevalier de Lamarck, was born. Had he lived he would now be a sprightly 278 years old. It is time for my annual birthday post. He was the first evolutionary biologist. In addition to world-class work in invertebrate taxonomy he argued for common descent and put forward a mechanism to account for adaptation. No not inheritance of acquired characters – everyone always knew that it was true. The mechanism was Use and Disuse. Organisms tried to solve their problems by using (or disusing) their organs, and the resulting changes would be adaptive and of course would be passed on to the next generation. Lamarck also believed that, in addition, there was an overall force in descent of organisms in nature leading to an increase of complexity.

Is Lamarckism dead now? Well, yes and no. Let me explain …

There are people who have evolutionary theories that they think are Lamarckian. A prime example is Dr. Eva Jablonka, an evolutionary biologist at the Cohn Institute for the History of Philosophy of Science and Ideas at Tel Aviv University. She declares herself a Lamarckian, invoking epigenetic changes of DNA as her mechanism (see her Wikipedia page).

Does that mean she believes that, in addition to the known physical laws, that there is an inherent complexifying force in nature? I don’t think so. And does she believe that use and disuse of organs, together with epigenetic inheritance, explains adaptations? I can’t see that she does.

She does identify her views as Lamarckian in her web page at the Third Way of Evolution website (here). She is also a member of the Extended Evolutionary Synthesis group (see here). She has written many books, and you can easily find YouTube videos of lectures where she advocates views she calls Lamarckian. For a critical review of her arguments, see Bruce Walsh’s book review in volume 50, number 5, 1996 in Evolution (here).

Leaving aside her main concerns, which are to vindicate the importance of epigenetic phenomena in evolution, and to place them in the context of other forms of non-Mendelian inheritance, we can ask whether Lamarck would recognize her views as his own. I can’t see that he would. “Lamarckian” evolutionary phenomena may be repeatedly invoked by a generation of skeptics of the Modern Evolutionary Synthesis. But in their view evolutionary changes that involve epigenetic variations in populations come from natural selection acting on those variations. By contrast, use and disuse is different: a kind of directed mutation. Lamarck’s theory invoked, in effect, directed mutation, and did not depend on selecting among variations in the population.

Lamarck is being invoked against the Modern Synthesis. But his theories of change are not.