The History of Epigenetics and the Science of Social Progress

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by Shea Robison (@EpigeneticsGuy)

The importance of Jean-Baptiste Lamarck and of Lamarckism in the contemporary debates about epigenetics and genetics is difficult to overstate, primarily because one of the most common epithets used against contemporary epigenetics is that it is ‘Lamarckian’, which distinction is deemed sufficient to dismiss any subsequent discussion. As discussed here, such references demonstrate fundamental misunderstandings of both Lamarckism and epigenetics. The contemporary indictment of epigenetics qua Lamarckism, though, is quite helpful in revealing the underlying political and ethical commitments of genetics.

As I discuss here, the scientific flaws of Lamarckism—which, although numerous, are also understandable in its historical context—are actually of little relevance for contemporary epigenetics. What is relevant is that Lamarckism is invoked so often as a conversation-stopper [1] about contemporary epigenetics. The guiding model of my project helps to explain why these unsubstantiated epithets are being used against epigenetics, as a means to protect the often unrecognized underlying political and ethical commitments of genetics. This post will use the experiments of August Weismann to demonstrate how this has worked in the past.

Weismann v. Lamarck?

The scientific rationale for the rejection of Lamarckian inheritance—and, by extension, much of contemporary epigenetics—is largely provided by August Weismann’s experiments on whether mutilations of parents (i.e., cutting off the tails of 22 generations of rats) could be passed on to their offspring. (Similarly, the repeated need for circumcision in Jewish populations is still often offered as anecdotal proof for the rejection of the inheritance of acquired characteristics [2].)

From his experiments Weismann postulated a tissue barrier that protects those cells involved in sexual reproduction (germline cells) from environmental influences registered in the cells which constitute the body of an organism (somatic cells). This barrier is what prevents Lamarckian inheritance. With the support of experiments by Castle and Phillips in 1911 of the transplantation of albino guinea pig ovaries into non-albino guinea pigs which appeared to verify empirically that adaptations of such characteristics were not heritable [3], Weismann’s Barrier soon gained widespread acceptance and still constitutes a central assumption of the conventional orthodoxy of genetics as an inviolate barrier against the transmission of acquired traits [4]. Notably, there have been significant modifications of this concept since Weismann, but the contemporary articulation of this barrier is still that there must necessarily be some kind of barrier which prevents the transfer of genes from the somatic cells to germline cells [5].

However, there are a couple of substantial issues with both the history and the science of this concept. First, according to E.J. Steele, these experimental protocols did not accurately reflect the mechanisms of inheritance as theorized by Lamarck and thus were not actually a valid test of Lamarckism [6]. Second, the results of these experiments were obviously only deductively valid (i.e., while these experiments showed that the specific mechanisms of tail generation may not be subject to transgenerational inheritance, it is logically invalid to infer that these results definitively disprove the possibility of the inheritance of acquired characteristics in general). Yet the results of these experiments were promulgated as definitive disproof of the inheritance of acquired characteristics.

Even Weismann himself admitted that his justification for this barrier was based on almost pure speculation only tenuously informed and supported by empirical evidence [7]. To be fair, Weismann also declared that his intent was to speculate so as to spur further research in this area, and acknowledged that his ideas were likely woefully incomplete and would require much experimental work to verify or disprove. Regardless, this concept was quickly accepted as being presumptively true without much of the empirical work Weismann recommended be done.

While subsequent research has largely supported the assumption of Weismann’s Barrier, the actual physical grounding of this barrier has not been established until quite recent [8]. Notably, as the actual make-up of this barrier is just now being verified, this same work is also establishing that there is no such inviolable barrier per se, but rather a collection of mechanisms which prevent the transmission of acquired traits [9]. At the same time, work in this area is also providing evidence that genetic material does cross this supposedly inviolable soma-germline ‘barrier’ [10], that genes may be transferred both vertically (between parents and offspring) and horizontally (i.e., between unrelated organisms) [11], and that there are epigenetic mechanisms which do allow the inheritance of environmentally induced characteristics [12].

The look before the leap

So why did Weismann, one of the most respected experimental scientists of his time, see fit to engage in such speculative theorizing to derive his crowning achievement? And why did a concept with so little initial empirical support so quickly attain the status of a presumptively true assumption to become a cornerstone of contemporary genetics that only now is being questioned?

The conventional view of science and of the history of genetics is that Weismann ‘merely’ took a creative leap which contributed to subsequent advances in our scientific understanding of biology. This may be true, but a reasonable hypothesis—per the guiding model of this project—is that there were also political and ethical impetuses which influenced the direction and the trajectory of this leap.

This hypothesis finds significant support in the context of Weismann’s bitter—and well cataloged—dispute with Herbert Spencer [13]. This dispute between Spencer and Weismann, according to Stephen Jay Gould, was the “focal point and most widely cited set of documents in the great debate between ‘neo-Darwinism’ and ‘neo-Lamarckism,’ perhaps the hottest subject in evolutionary theory of the 19th century” [14].

In this ‘debate’ Weismann disagreed vociferously with Spencer—and, by extension, with Freidrich Engels and Karl Marx and other neo-Lamarckians of this time—who used Lamarckism as scientific support for their theories of social improvement. Many of these neo-Lamarckians preferred Lamarckism for the emancipatory possibilities it offered as in contrast to the practical immutability of biological essences promoted first by conventional religion, and continued by Darwin and neo-Darwinists. Instead of organisms (and humans in particular) being fixed in their basic endowments, or subject to the grace of God or random forces for change, dramatic changes were deemed possible for these social reformers through the guidance and instruction of their environments [15].

For example, in 1891 the prominent American geologist and president of the American Natural History Museum Henry Fairfield Osborn described the social implications of these differences in biological science, writing that:

If the Weismann idea triumphs, it will be in a sense a triumph of fatalism; for, according to it…each new generation must start de novo, receiving no increment of the moral and intellectual advance made during the lifetime of its predecessors. It would follow that one deep, almost instinctive motive for a higher life would be removed if the race were only superficially benefited by its nurture, and the only possible channel of actual improvement were in the selection of the fittest chains of race plasma[16].

For these reasons, as described by Lenoir and Ross in their brief history of natural museums in England, Lamarckism was a fundamental aspect of many of the rationalist (i.e., secular), progressive reform movements of the 1800s in which “a belief in the perfectability of humankind and the self-organizing power of matter according to natural laws [was] joined to a faith in the environment as a determinant of form and character” [17]. This combination of scientific and philosophical beliefs supported the expectation that “through the appropriate social and material environment, humanity’s spiritual qualities could be molded as a prelude to political change” [18].

It was against such politically and ethically loaded ideas that Weismann and other Darwinists and neo-Darwinists set themselves. Although much of this debate was couched in scientific language about ostensibly scientific subjects, underneath much of it were competing worldviews as to the proper place of humanity on the earth and in the universe. In other posts, I have likewise written about the significant though largely ignored roles of competing political ideologies in the scientific history of genetics and epigenetics, as well as about the ideological implications of epigenetics.

In hindsight we are able to see how this dynamic has played out in the early and mid 20th century, with conventional genetics being declared the winner (i.e., the one true science) while the other combatants have been relegated as quaint relics of a bygone era (i.e., unscientific). However, the recent (re)emergence of contemporary epigenetics strongly suggests that neither the motives nor the outcomes of these ‘scientific’ debates were as pristine as they are now assumed to be.

Likewise, that these ideological influences on science in the past are as obvious as they are now also suggests that ideological influences are similarly present in science today. That most scientists working today would be offended at this suggestion that ideology has any influence in their work is understandable, but this umbrage does not mean that such influences are not operative today as well (how aware were Weismann or any of the other scientists of his time of the now obvious ideological influences on their work?).

Per the guiding model of this project, these political and ethical influences on science—and scientific influences on politics and ethics—are always present. My project is to identify the effects of these political and ethical influences on the emergence of the science of epigenetics.

I am curious to hear what you think so far. Leave your comments below and I will respond.

Also, if you find these thoughts I’ve shared interesting and worthwhile, Like this post, Reblog it, or Tweet about it using the buttons on this page.

[1] Rorty, Richard. 1994. “Religion as a Conversation-Stopper,” Common Knowledge 3(1): 1-6.

[2] Levin, Harold. 2009. The Earth Through Time. 8th ed. Hoboken, NJ: Wiley. 133.

[3] Chiras, D. D. (2013). Human biology. Jones & Bartlett Publishers.

[4] Alexander, Richard. 1979. Darwinism and Human Affairs. Seattle: University of Washington Press.

[5] Steele, E.J. 1999. Lamarck’s Signature: How Retrogenes Are Changing Darwin’s Natural Selection Paradigm. Basic Books.

[6] Steele, E.J. 1999. Lamarck’s Signature: How Retrogenes Are Changing Darwin’s Natural Selection Paradigm. Basic Books.

[7] Weismann, August. 1892. Essays Upon Heredity and Kindred Biological Problems. Clarendon Press, 81-82.

[8] Sabour, D., & Schöler, H. R. (2012). Reprogramming and the mammalian germline: the Weismann barrier revisited. Current opinion in cell biology24(6), 716-723.

[9] Solana, J. (2013). Closing the circle of germline and stem cells: the Primordial Stem Cell hypothesis. EvoDevo4(1), 1-17

[10] Boyce, N. (2001). Trial halted after gene shows up in semen. Nature,414(6865), 677-677.

[11] Riley, D. R., Sieber, K. B., Robinson, K. M., White, J. R., Ganesan, A., Nourbakhsh, S., & Hotopp, J. C. D. (2013). Bacteria-human somatic cell lateral gene transfer is enriched in cancer samples. PLoS computational biology9(6), e1003107.

[12] Sharma A, Singh P. Detection of transgenerational spermatogenic inheritance of adult male acquired CNS gene expression characteristics using a Drosophila systems modelPLoS One 4, e5763 (2009); Sharma, A. (2013). Transgenerational epigenetic inheritance: focus on soma to germline information transfer. Progress in biophysics and molecular biology, 113(3), 439-446; Sharma A. Novel transcriptome data analysis implicates circulating microRNAs in epigenetic inheritance in mammalsGene 538:366-372 (2014); Sharma A. Bioinformatic analysis revealing association of exosomal mRNAs and proteins in epigenetic inheritanceJ. Theor. Biol. 357:143-149 (2014).

[13] Bowler, P. J. (1992). The eclipse of Darwinism: Anti-Darwinian evolution theories in the decades around 1900. JHU Press.

[14] Gould, S. J. (2002). The structure of evolutionary theory. Harvard University Press.

[15] Morange, M. (2010). What history tells us XXII. The French neo-Lamarckians. Journal of biosciences35(4), 515.

[16] Osborn, Henry Fairfield. 1891. The Present Problem of Heredity. The Atlantic Monthly 57, 363.

[17] Lenoir, Tim and Cheri Ross. 1996. The Naturalized History Museum. In Peter Galison and David Stump, eds., The Disunity of Science: Boundaries, Contexts, and Power. Stanford; Stanford University Press: pp. 370-397.

[18] Lenoir, Tim and Cheri Ross. 1996. The Naturalized History Museum. In Peter Galison and David Stump, eds., The Disunity of Science: Boundaries, Contexts, and Power. Stanford; Stanford University Press: pp. 370-397.

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