Wed 8 Nov 2006
Jean-Baptiste Lamarck proposed, way back in 1801, that the effect of the environment and an organism’s response to it was the mechanism for change over time and generations. His theory was disputed and derided by Georges Cuvier who could not admit to change in organisms – that they were integrated wholes incapable of change in form or function. Cuvier was a giant of scientific thought and prestigue in many other fields, so his influence was so great that even Lamarck’s patron, Buffton abandoned his support of Lamarck.
Poor Lamarck, who died in poverty and obsurity, is finally being vindicated by a branch of science called epigenetics. It turns out that many mechanisms of gene expression and phenotyping are heritable and reversable after all! These mechanisms operate without necesarily effecting the genome of the organism itself. Many of these mechanisms are related to the effect on the organism by its environment and the stresses it undergoes.
Lamarck’s theory proposed as his first law that time and circumstances cause the organs and structures of an organism to be strengthened or atrophied by use and disuse. His second law was that these variations are heritable. Dispite Darwin’s credit to Lamarck in the preface to The Origin of Species, the theory of natural selection completely eclipsed Lamarck’s theory sixty years after Lamarck first postulated it in 1801. The final nail in Lamarck’s theory was Mendel‘s discovery of genetics in the 1860’s. Genetics provide the mechanism by which both the discrete and continuous variation in an organism develops over genereations – the randomizing force of combination and continuation which gives natural selection the ability to filter the “fittest” organisms to survive in their particular environment.
Since then, the combination of natural selection and genetics was so overpowering that Lamarck’s views were considered only a scientific historical footnote and a dead end theory, like cold fusion. All questions of the development of speciation and adaptation to the environment were by natural selection. Any other view was heresy.
The Baldwin Effect was discovered by James Mark Baldwin around the turn of the century, showing that learned behaviours can be passed on to offspring as an improved ability to learn that class of knowledge or response. This important discovery remained obscured until recently when it was publicized and became widely circulated.
Research published in The-Scientist.com on the “Dutch Hunger Winter” shows that the grandchildren of those who experienced prepubescent starvation have significantly reduced birthweight. This article also details several other studies with similar results.
Science Magazine had a special edition in 2001 detailing the many areas of research then going on which show that there are several mechanisms for Lamarckian inheritance, including the gene expression effects of protiens and RNA, and how they can effect the development of an organism.
March 2006 Environmental Health Perspectives magazine had a special edition covering the epigenetic field. One of the articles showed how the long held belief that epigenetic effects were erased at each generation was incorrect, and that some effects are hertiable over four generations, and perhaps more. These discoveries have many implications on disease. For example, studies on gene suppression or activation by methelation of Cytozine, one of the bases of DNA and RNA can have great diagnostic value in diagnosing cancers.
Discover Magazine‘s November 2006 issue’s cover article DNA is not destiny shows how parental behavior, DNA methalation and a host of other environmental effects change the behaviour, phenotyping and susceptability to disease of mice and other animals, and that at least some of these changes are heritable.
The knowledge that the environment changes the expression of genes, and that these changes in expression are heritable validates Lamarck’s original thesis. That it was easier to show that Mendel’s genetic patterns were stable and easily reproduced hid the truth of Lamarck’s observations for hundreds of years. Perhaps this example will show that rarely is there truth in only one viewpoint. All visionaries see part of the truth, and rarely see it all.
No Responses to “ Lamarckism, long scientific heresy, is validated after 200 years. ”
You must be logged in to post a comment.