We have heard quite a lot in recent times about a resurgence of “Lamarckian” mechanisms, based largely on findings involving epigenetics. In this case, environmental differences cause changes in the patterns of expression of genes, and these alterations can sometimes be passed on through at least a few generations.
There are two reasons why it is inaccurate to consider this kind of change in heritable characteristics induced by the environment as “Lamarckian inheritance”.
One, Lamarck did not think that the environment imposed direct effects on organisms that were then passed on. He argued that the environment created needs to which organisms responded by using some features more and others less, that this resulted in those features being accentuated or attenuated, and that this difference was then inherited by offspring. As he wrote,
It is now necessary to explain what I mean by this statement: The environment affects the shape and organization of animals, that is to say that when the environment becomes very different, it produces in the course of time corresponding modifications in the shape and organization of animals. It is true, if this statement were to be taken literally, I should be convicted of an error; for, whatever the environment may do, it does not work any direct modification whatever in the shape and organization of animals. [Translated as in Kampourakis and Zogza (2007)]
What people insist on dubbing “Lamarckian inheritance” in the context of epigenetics is actually closer to the view held by Darwin than by Lamarck. In the second part of his 1858 joint paper with Wallace (excerpted from an 1857 letter to Asa Gray), Darwin wrote,
Selection acts only by the accumulation of slight or greater variations, caused by external conditions, or by the mere fact that in generation the child is not absolutely similar to its parent.
…
Now take the case of a country undergoing some change. This will tend to cause some of its inhabitants to vary slightly—not but that I believe most beings vary at all times enough for selection to act on them. Some of its inhabitants will be exterminated; and the remainder will be exposed to the mutual action of a different set of inhabitants, which I believe to be far more important to the life of each being than mere climate.
We can read similar things in the Origin:
I have hitherto sometimes spoken as if the variations—so common and multiform in organic beings under domestication, and in a lesser degree in those in a state of nature—had been due to chance. This, of course, is a wholly incorrect expression, but it serves to acknowledge plainly our ignorance of the cause of each particular variation. Some authors believe it to be as much the function of the reproductive system to produce individual differences, or very slight deviations of structure, as to make the child like its parents. But the much greater variability, as well as the greater frequency of monstrosities, under domestication or cultivation, than under nature, leads me to believe that deviations of structure are in some way due to the nature of the conditions of life, to which the parents and their more remote ancestors have been exposed during several generations. I have remarked in the first chapter—but a long catalogue of facts which cannot be here given would be necessary to show the truth of the remark—that the reproductive system is eminently susceptible to changes in the conditions of life; and to this system being functionally disturbed in the parents, I chiefly attribute the varying or plastic condition of the offspring. The male and female sexual elements seem to be affected before that union takes place which is to form a new being. In the case of “sporting” plants, the bud, which in its earliest condition does not apparently differ essentially from an ovule, is alone affected. But why, because the reproductive system is disturbed, this or that part should vary more or less, we are profoundly ignorant. Nevertheless, we can here and there dimly catch a faint ray of light, and we may feel sure that there must be some cause for each deviation of structure, however slight.
Two, the idea of inheritance of acquired characteristics predates Lamarck, was the dominant view in his time, and remained common long afterward. As Morse (1903) wrote,
Jean Lamarck first used the term “acquired character” to designate characters such as these and to him are are we to look for the first clear statement of the case. By this it is not to be understood that the idea of the transmission of acquired characters arose with Lamarck. No great generalization ever arose or ever can arise with one man alone. The attribution of the idea of the transmission of acquired characters to Lamarck falls in the same category as attributing evolution to Darwin.
Zirkle (1946) was more forceful yet,
What Lamarck really did was to accept the hypothesis that acquired characters were heritable, a notion which had been held almost universally for well over two thousand years and which his contemporaries accepted as a matter of course, and to assume that the results of such inheritance were cumulative from generation to generation, thus producing, in time, new species. His individual contribution to biological theory consisted in his application to the problem of the origin of species of the view that acquired characters were inherited and in showing that evolution could be inferred logically from the accepted biological hypotheses. He would doubtless have been greatly astonished to learn that a belief in the inheritance of acquired characters is now labeled “Lamarckian,” although he would almost certainly have felt flattered if evolution itself had been so designated.
Darwin, like Lamarck, invoked use and disuse and inheritance of acquired changes1; the Origin includes an entire section on it, the first part of which reads,
Effects of Use and Disuse.—From the facts alluded to in the first chapter, I think there can be little doubt that use in our domestic animals strengthens and enlarges certain parts, and disuse diminishes them; and that such modifications are inherited. Under free nature, we can have no standard of comparison, by which to judge of the effects of long-continued use or disuse, for we know not the parent-forms; but many animals have structures which can be explained by the effects of disuse. As Professor Owen has remarked, there is no greater anomaly in nature than a bird that cannot fly; yet there are several in this state. The logger-headed duck of South America can only flap along the surface of the water, and has its wings in nearly the same condition as the domestic Aylesbury duck. As the larger ground-feeding birds seldom take flight except to escape danger, I believe that the nearly wingless condition of several birds, which now inhabit or have lately inhabited several oceanic islands, tenanted by no beast of prey, has been caused by disuse. The ostrich indeed inhabits continents and is exposed to danger from which it cannot escape by flight, but by kicking it can defend itself from enemies, as well as any of the smaller quadrupeds. We may imagine that the early progenitor of the ostrich had habits like those of a bustard, and that as natural selection increased in successive generations the size and weight of its body, its legs were used more, and its wings less, until they became incapable of flight.
As was argued by Parkyn (1911),
It is difficult to understand how anyone well acquainted with Darwin’s works can come to any other conclusion than that he firmly believed in Lamarck’s principle of the transmission of characters acquired by use.
Designating epigenetics as Lamarckian greatly misconstrues what Lamarck actually argued. The parts of Lamarckian theory to which it does refer were likewise part of early Darwinian theory. In short, there is no vindication of Lamarck’s mechanism to be granted by epigenetics. That said, there is no doubt that Lamarck’s contributions to evolutionary thinking should be better appreciated. Certainly, the first step toward this would be an effort to understand what he actually proposed.
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Updated notes:
1) See the comments discussion. Wilkins has pointed out that Darwin was not simply a “Lamarckian” in terms of new traits arising through need+use/disuse (rather, he suggested that the strength of inheritability of traits is affected by use). However, Darwin did invoke disuse as a reason that traits could be lost which is enough to show that he did not throw out use and disuse as a mechanism of trait change.
I said something about this myself. I don’t think Darwin believed in the inheritance of acquired characters. I think he believed that prior characters were more strongly inherited the more they were used, but not those characters like, say, a callus, that are acquired during maturation.
Of course I don’t know exactly whether this is what Lamarck thought either. I do not trust the neo-Lamarckians reportage – they often reinterpret history to suit themselves (as do the “Darwinians” of the fin de siecle as well).
Here are Lamarck’s Two Laws:
“First Law.
“In every animal which has not passed the limit of its development, more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ, and gives it a power proportional to the length of time it has been so used; while the permanent disuse of any organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappears.
“Second Law.
“All the acquisitions or losses wrought by nature on individuals, through the influence of the environment in which their race has long been placed, and hence through the influence of the predominant use or permanent disuse of any organ; all these are preserved by reproduction to the new individuals which arise, provided that the acquired modifications are common to both sexes, or at least to the individuals which produce the young.”
The first law is something shared by Darwin. And everyone else. The second is not something Darwin adopted.
Very timely post, as I’m teaching about this stuff today!
It is still debated to what degree some environmental modifications act simply as “deformations” of the environment, vs. other that are complex, “built in” response. West Eberhardt discusses this in her book. I think Lamarcks “internalism” is very interesting. A necessary concept.
Very, very silly title for this post. It reveals merely darwinolatrous motivations. BOTH lamarck and darwin said it. Actually, Lamarck first, but we need not bring that up… specially since both fared better than more recent gene-happy eodarwinians who for so long blissfully ignored the effects of environmental interactions on inheritance
Very, very silly title for this post. It reveals merely darwinolatrous motivations. BOTH lamarck and darwin said it.
Actually, the title refers to the claim that the environment directly affects traits and that this is then passed on. Lamarck didn’t say that but Darwin did. I also don’t see how you get “darwinolatrous” out of this, because, if anything, this post is critical those who attribute false ideas to Lamarck and not also Darwin.
But (and I’m not supporting the tone of the previous commenter) Darwin said only that circumstances would affect variation. This is, to a real extent, quite true – mutations are affected by local conditions, especially ones we have recently created. What he did not say was that traits acquired by the animals lifestyle were inherited.
It’s hard to argue that Darwin did not consider use and disuse when he had a major discussion of it in the Origin. In any case, the larger point was that Lamarck did not say that simple exposure to an environment causes heritable variation, whereas Darwin did. Therefore, the argument that epigenetics shows a Lamarckian process rather than one more like something Darwin invoked, is inaccurate.
Ryan, either you aren’t getting it, or I am not expressing myself clearly (the latter being the default hypothesis).
Darwin did think that use and disuse influenced heredity, but it was not the source of the traits. It merely “strengthened or weakened” the inheritance of traits that occurred for other reasons, which we independent of the lifstyle of the organisms. So using eyesight meant it would be more strongly inherited, and not using it meant that it would tend to disappear as in cave fishes. But the origins of eyesight are not based on the acquisition of sightedness by exercise during the animal’s life.
Lamarck, at least as he is often interpreted, held that by the action of the organism under “besoin” (or need) novel traits would be acquired and passed on. Darwin did not hold that.
I get it, and I’m not disagreeing with you. The post includes three arguments.
One, that the claim that epigenetics is resurrecting “Lamarckian” processes is false. This is because Lamarck did not suggest that environmental exposure causes heritable changes. Darwin did say something like this, however. I am not giving Darwin credit for it, I am criticizing the claims that epigenetics is “Lamarckian”.
Two, the inheritance of acquired characters more generally is not “Lamarckian” either. It was the common position in his time and it persisted to an extent in Darwin’s thinking.
Three, use and disuse was not thrown out when Darwin came. Darwin maintained some aspect of it also.
I am not claiming that Darwin was just a Lamarckian; my point is just that the history implied in claims of “Lamarckian” processes is vastly oversimplified.
Ah, then the problem was my lack of comprehension. Yes, I totally agree: I’ve been saying that epigenetics isn’t Lamarckism for years (and, if I may self-promote, published this 8 years back). I also think Lamarck deserves a better deal than he gets from the opposition of the Weismannians and the misrepresentation of his ideas by the neo-Lamarckians. Interestingly, Romanes defended Darwin against those he labelled “neo-Darwinians” who failed to take the master’s ideas seriously on use and disuse and even pangenesis. Romanes is the only scholar to take pangenesis seriously that I can find – even Lankester didn’t.
Here’s one – do you know of any clear articles on the notion of use and disuse in evolutionary thought that covers both Lamarck’s and Darwin’s thinking properly?
“and, if I may self-promote, published this 8 years back”
You may — ref?
[*ahem*]
Wilkins, John S. 2001. The appearance of Lamarckism in the evolution of culture. In Darwinism and evolutionary economics, edited by J. Laurent and J. Nightingale. Cheltenham UK: Edward Elgar.
As to your second question, oddly, no. You might make a start here:
Hull, David L. 1984. Lamarck among the Anglos. In Introduction to reprinted edition of J. B. Lamarck’s Zoological Philosophy: An Exposition with Regard to the Natural History of Animals. Chicago: Chicago University Press.
However I can’t say right now how well that has stood up in the light of more recent scholarship.
Disclaimer: nevermind the poor english, I’m not a native speaker! (8^P
the claim that epigenetics is resurrecting “Lamarckian” processes is false. This is because Lamarck did not suggest that environmental exposure causes heritable changes. Darwin did say something like this, however.Lamarck indeed suggested that environment causes heritable changes. Chapter VII of his Philosophie Zoologique is titled “On the influence of the circumstances on the actions and habits of animals, and the influence of these living bodies in modifying their organisation and structure”, and he follows by stating his two laws (as cited by Wilkins in the 1st comment) as an explanation (or description) of the process of evolution by the inheritance of acquired traits.
the inheritance of acquired characters more generally is not “Lamarckian” either. It was the common position in his time and it persisted to an extent in Darwin’s thinking.True. But, in your post “Natural selection before Darwin”, you proposed that “… [T]he idea [of natural selection] had been around for at least six decades before Darwin published the Origin, and it was not until someone of Darwin’s genius developed the idea that evolution assumed its position as the underlying theme of all biology”.
Likewise, the idea of inheritance of acquired traits (I.A.T.) had been around for a long time, but it was not until someone of Lamarck’s genius developed the idea that it has been seriously incorporated into the evolutionary thought of XIX century. As Darwin put it in the 3rd edition of The Origin, “Lamarck was the first man whose conclusions on [the evolution of species] excited much attention”, adding that “he attributed something to the direct action of the physical conditions of life, something to the crossing of already existing forms, and much to use and disuse, that is, to the effects of habit”. If we are to use the same standard to judge both case, Lamarck must be viewed as the champion of I.A.T. just the same way that Darwin is the champion of Natural Selection.
No, natural selection was mentioned in very brief outline in obscure publications by a few people before Darwin. Quite the opposite, acquired characters reflected the dominant view long before Lamarck.
“I don’t think Darwin believed in the inheritance of acquired characters. I think he believed that prior characters were more strongly inherited the more they were used, but not those characters like, say, a callus, that are acquired during maturation.”
Amazing statement. And a good illustration of the tendency to exagerate the modernity of Darwin’s thinking. We know that Mendel wasn’t a Mendelian, that Newton wasn’t a Newtonian, Maxwell no Maxwellian. And so forth. It’s maybe about time that someone writes the article ‘Darwin wasn’t a Darwinian.’
Darwin was in reality a 100% ‘lamarckist.’ In contrast with Lamarck, he even developed a ‘lamarckian’ theory of heredity: pangenesis. It is true though (and of course), that his theory of evolution was in other respects much more modern than Lamarck’s theory (natural selection, common descent, …).
“From the facts alluded to in the first chapter, I think there can be little doubt that use in our domestic animals strengthens and enlarges certain parts, and disuse diminishes them; and that such modifications are inherited.”