Debating philosophers: Epigenetics

Qiaoying Lu and Pierrick Bourrat are philosophers in Australia.¹ Their research interests include evolutionary theory and they have taken an interest in the current debate over extending evolutionary theory. That debate has been promoted by a small group of scientists who, by and large, are not experts in evolution. They claim that current evolutionary theory—which they define incorrectly as the 1960s version of the Modern Synthesis—needs to be overthrown or extended by including things like epigenetics, niche construction, developmental biology, and plasticity [New Trends in Evolutionary Biology: The Program].

Lu and Bourrat have focused on epigenetics in their recent paper [Debating philosophers: The Lu and Bourrat paper]. They hope to reach an accommodation by re-defining the evolutionary gene as: "any physical structure that causes a heritable variation." Then they go on to say that, "we define the phenotype of an evolutionary gene as everything that the gene makes a difference to when compared to another gene."

By doing this, they claim that epigenetic changes (e.g. transient methylation) fall with the new definition. Therefore, epigenetics doesn't really represent a challenge to evolutionary theory. They explain it like this ....

With the conceptions of gene, environment and phenotype for gene-centric evolutionary theory in place, we now assess the question of whether evolutionary theory requires a major conceptual change to accommodate epigenetic inheritance. There seems to be a spectrum from conservative to more radical views on this issue. Some think that epigenetic inheritance may have the potential to play an important role in evolutionary processes, but that it is not a contradiction of the classic view on genetic inheritance, only an augmentation (Haig [2007]; Pigliucci [2009]). Others claim that the incorporation of new data and ideas about hereditary variation requires a version of Darwinism that is very different from the gene-centric view (Jablonka and Lamb [2007]; Laland et al. [2014]; Laland et al. [2015]). Our position is twofold. On the one hand, we argue for an extended understanding of the gene in evolutionary theory, rather than a restricted DNA-based account as adopted by most authors. This extension, as we have shown in Section 2.1, corresponds well to the formal evolutionary theory and thus also to the gene-centric tenet of the MS. On the other hand, as we will argue in the following section, given our framework, evolutionary theory can accommodate mechanisms of epigenetic inheritance without a profound conceptual change. Our position is very close to Helanterä and Uller’s ([2010]) suggestion that different inheritance systems may share conceptually similar features but may have different abilities to couple inheritance and selection. Two major challenges to the MS brought up by epigenetic inheritance will be considered.

Here's the problem. I've been following this debate over extending evolutionary theory for almost forty years and I've been paying particular attention to the latest "challenge" that arose in the last decade beginning with the Altenberg 16. I've read the books and I even attended the Royal Society Meeting last November: New trends in evolutionary biology: biological, philosophical and social science perspectives. I've talked to many evolutionary biologists, including some who were at that meeting. I think it's safe to say that most experts in evolutionary biology do not see epigenetics as a threat to current evolutionary theory, with its heavy emphasis on population genetics, and they do not see any need to shift paradigms. Most see epigenetics as a rather minor phenomenon in evolution. Furthermore, it's not new. Modified bases have been known for 40 years and modified histones have been around for almost as long. The definition of "epigenetics" is so nebulous as to be practically useless and hardly different than regulation of gene expression, which was never seen as a threat to evolutionary theory [What the heck is epigenetics?].

But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown.
                      Carl SaganIf I were a philosopher of biology, I would concentrate on the meaning of the current debate and on how proponents of an extended evolutionary synthesis (EES) have framed the discussion around a false view of modern evolutionary theory [More calls to extend the defunct Modern Synthesis]. I would explore the reasons for such a debate and what the EES proponents hope to achieve. I would take care to avoid falling into the trap of believing the hype promoted by the likes of Suzan Mazur and others who seem more interested in seeking publicity than in supporting good science.

Finally, I would be honest with my readers by quoting leading experts in current evolutionary theory to show that most of them dismiss the controversy and ignore the challenges to modern theory. This would require a discussion about real paradigm shifts and how to distinguish between real change and fake change (paradigm shafts). The last thing I would would do is to take sides and try to lecture evolutionary biologists on how to modify their theories to accommodate epigenetics.

This would be a wonderful thesis topic in the history and philosophy of science but it really has much more relevance to epistemology and the behavior of scientists than to actual threats to evolutionary theory. It would make a wonderful case study on where biology has gone wrong and why so many scientists (and philosophers) have fundamental misconceptions about evolution, genetics, and genes. Instead, the Lu and Bourrat paper is just one more example of why biological scientists are skeptical about the contribution philosophers can make to their field.

This is the last of a series of posts on the Lu and Bourrat paper. Here's the complete list.

• Debating philosophers: The Lu and Bourrat paper [This post.]
  
• Part I: The Modern Synthesis
• Part II: The difference between genes and alleles
• Part III: The evolutionary gene
• Part IV: The molecular gene
• Part V: Epigenetics

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1. Qiaoying Lu is sometime listed as a member of the Department of Philosophy at Macquarie University in Sidney Australia and sometimes as a graduate student at Sun Yat-Sen University in China. She appears to be a visiting graduate student in Sydney. Pierrick Bourrat is a currently a research fellow at Macquarie University in Sidney although his address on the paper is the University of Sydney. He identifies his research interests as: "Pierrick's main research interest is the philosophy of biology and more particularly the evolutionary side of it. His other areas of interest include the psychology of altruism, cultural evolution and the cognitive science of religion."