Myth 3: Darwin was actually a Lamarckian
This one is subtle. It implies that Darwin, because he lacked a Mendelian account of heredity, was not actually a “true” (or Neo-)Darwinian. The error depends on the extent of what is named as a school of thought in science and why.
As far as I know, the term “Lamarckian” for those who think heredity is acquired during the parental generation and passed on to progeny, was coined by August Weismann, a pre-genetics developmental biologist with an interest in heredity. He contrasted this with his own view, that germ cells – the cells in which inheritance is passed on (sperm and egg in animals) – are isolated from what happens to the post-conception body, or in his terminology, they are sequestrated, now called the “Weismann Barrier“. This was 60 years or so before DNA was given structure as a mechanism, and 10 years before genetics proper got going, so it really has little to do with DNA.
Darwin held the common view that inheritance was strengthened or weakened by the amount a trait was used by the maturing animal; this was not unique to Lamarck, and goes back to ancient accounts in which, via sympathetic magic, the developing fetus could be modified by the experiences of the pregnant mother. An example of this is in Genesis chapter 30. It is not right to call this “Lamarckian” or “Lamarckism”, as it was neither invented by Lamarck, nor is it strictly the sin that Weismann named thus, of thinking that the traits that were acquired during the lifetime of the parent would be passed on to the progeny. Darwin did not think that at all. He held that the traits arose in ways that were amenable to investigation (only not as yet), which caused variation. But because he had a problem of the loss of variation by averaging, he needed to explain how variation could be inherited so that natural selection could act upon it.
R. A. Fisher has a nice explanation of this in the first chapter of his 1930 Genetical Theory of Natural Selection . Assuming as (nearly) all did in Darwin’s day that heredity blends – that is, the parent’s individual differences average out in the progeny – after around 1000 generations all variance is lost. So variance needs to be maintained either by some other factor, such as use and disuse – Darwin’s term for the mechanism we wrongly term “Lamarckian” – or natural selection needs to be many factors higher than we think it really is. It is often said that if Darwin had read his Mendel, he’d have seen the solution to the blending problem, but I doubt it. Yes, Mendel’s hypothesis of particulate inheritance in fact does solve the blending problem, but it took scores of geneticists nearly twenty years to show this in the case of natural selection, the first proof being given in William Castle’s work in the second decade of the century and the new science of genetics, and later developed in detail by Fisher, Sewall Wright, and J. B. S. Haldane, among others. Whether Darwin would have been able to free himself from what he thought was a vast amount of empirical evidence, mostly from breeders and farmers, of use and disuse, and hence of blending, is debatable.*
But here’s what Darwin did not think: that the variation itself was acquired from parental experience, which is what we typically think of as being Lamarckian. This is what Mayr termed soft inheritance. Darwin held that variation arose in ways that he did not understand but were likely to be explicable in natural terms, but which were not correlated to the present or future needs of the organisms, just as we do today. Any variant that was used was more strongly inherited, and he developed his ill-fated Pangenesis theory to account for that “fact”, but this didn’t make the variants occur or more likely. So in any meaningful sense, Darwin was no Lamarckian.
The very use of the term “Lamarckian”, like the use of the contrasting term “Weismannian” (Griesemer 2005), is an act of battle. It raises a standard under which scientists and those fellow travellers like myself can rally against the enemy. To say that Darwin was a “Lamarckian” (especially when he was not in this regard) is a way of strengthening those who have, by their own account, refined Darwin and stripped him of error. Poor Darwin, who lacked the resources and data to know better! We have fixed his mistakes. On the other side, those who continually assert their heterodoxy by calling themselves “Lamarckian” (e.g., Jablonka and Lamb 1995, Steele, Lindley and Blanden 1998) seek to mark out their originality and again, claim to be fixing the mistakes of the past. Steele may be a Lamarckian in Weismann’s (though I rather doubt in Lamarck’s) terms, but Jablonka and Lamb are not. They are anti-Weismann, not anti-Darwin. The existence of mechanisms for taking somatic, non-nuclear, inheritance into subsequent generations in no way undercuts Darwin. Arguably it doesn’t even undercut Weismann, who held that inheritance at the cellular level was sequestered, not that it was DNA based (DNA at that time had not even been discovered, let alone given a role in inheritance). And from an evolutionary perspective, we need to show that this inheritance, termed “epigenetic”, persists long enough to have an evolutionary effect, which to my knowledge hasn’t yet been done.
Rather ironically, the history of the term “Lamarckian” shows us that there were a group of biologists who meliorated some of Darwin’s focal ideas – in particular the role of natural selection – who termed themselves “Neo-Lamarckians“, against whom Weismann strove. The tumult of ideas that were about in the late nineteenth century, a period in which natural selection was largely ignored or treated as secondary (Bowler 1983), led directly to the establishment of Mendelian genetics, and so to be “Lamarckian” meant one was immediately excluded from the new science, although as Koestler both documents and demonstrates (1971), neo-Lamarckism was still around late into the twentieth century. Natural selection itself was deprecated by the biological community from around 1870 or so to 1920, when mathematical models began to show its efficacy in a Mendelian world. Empirical support took even longer to acquire, although it is now ubiquitous (Bell 1996).
We need to be careful not to make any historical figure what they are not, and as I have repeatedly said, this is a common flaw in the use of history by scientists. Darwin was no Lamarckian. He was himself, and his errors are his own.
* Darwin’s use of anecdotal evidence is a singular moral lesson on why anecdote is not the singular of data. He saw what he expected on the basis of others seeing what they expected. It is to overcome these biases of seeing what you expect that Pearson and Fisher, among others, developed the use of statistical analysis of data sets. In a nice historical irony, both were continuing what they thought of as the Darwinian program.
Bell, Graham. Selection: The Mechanism of Evolution. New York: Chapman and Hall, 1996.
Bowler, Peter J. The Eclipse of Darwinism: Anti-Darwinian Evolution Theories in the Decades around 1900. Baltimore and London: John Hopkins University Press, 1983.
Castle, William E. “The Effect of Selection Upon Mendelian Characters Manifested in One Sex Only.” Journal of Experimental Zoology 8, no. 2 (1910): 185-92.
???. Heredity: In Relation to Evolution and Animal Breeding. New York, London: D. Appleton and Company 1911.
???. Studies of Inheritance in Guineapigs and Rats. Vol. Pub. No. 241. Washington: Carnegie Institution of Washington, 1916.
???. “Are Genes Linear or Non-Linear in Arrangement?” Proceedings of the National Academy of Sciences USA 5 (1919): 500?06.
???. “Is the Arrangement of the Genes in the Chromosome Linear? .” Proceedings of the National Academy of Sciences USA 5 (1919): 25?32.
???. “Piebald Rats and Selection: A Correction.” Amer. Naturalist 53 (1919): 370.
Fisher, Ronald Aylmer. The Genetical Theory of Natural Selection. Oxford UK: Clarendon Press, (rev. ed. Dover, New York, 1958), 1930.
Griesemer, James R. “The Informational Gene and the Substantial Body: On the Generalization of Evolutionary Theory by Abstraction.” In Idealization Xii: Correcting the Model. Idealization and Abstraction in the Sciences (Pozna, edited by Martin R. Jones and Nancy Cartwright, 59-115. Amsterdam: Rodopi Publishers, 2005.
Jablonka, Eva, and Marion J. Lamb. Epigenetic Inheritance and Evolution: The Lamarckian Dimension. Oxford; New York: Oxford University Press, 1995.
Steele, Edward John, Robyn A. Lindley, and Robert Vincent Blanden. Lamarck’s Signature: How Retrogenes Are Changing Darwin’s Natural Selection Paradigm, Frontiers of Science. St Leonards, N.S.W.: Allen & Unwin, 1998.