*Skip to below the videos if you don’t care about an aside about doctors.
I almost feel bad focusing this piece on one article in particular. I’ve been squinting skeptically at the talk surrounding epigenetics for months now. Because of that, much of what follows is directed at pop science journalism as much as anything.
I can’t bring myself to actually feel all that bad because Dr. Hyman is a doctor. Not only is he a doctor, but he brings up his doctoryness pretty much everywhere. And that’s fine, but training to be a medical doctor doesn’t necessarily provide special training in nutrition, exercise physiology, et cetera. It’s a problem because people respect doctors. It seems to me that people also tend to respect medical doctors (Dr. Hyman’s flavor) more than PhDs. Unfortunately for reality, the converse should often be true. The brief training medical doctors get in nutrition and exercise physiology has a higher probability of being dated (however slightly) when it comes in the form of chapters of generalized books and/or when it is taught by non-specialists. It’s certainly true that some medical doctors have stepped up their game and are exempt from this criticism, and that isn’t the point. It’s a problem of automatically granted authority where none should be granted. A recent exchange between Deepak Chopra (and M.D.) and Sam Harris (Ph.D. in neuroscience) illustrates this somewhat.
Scientific claims by Deepak Chopra
Response by Sam Harris (rewind to beginning for a funny moment: Michael Shermer calls Deepak “woo woo”)
Hilarious: Leanord Mlodinow (theoretical physicist, co-authored 2 books with Stephen Hawking) pwns Deepak
The Meat of It
“Science is now proving what we all knew intuitively—that how we live, the quality of our relationships, the food we eat, how we use our bodies, and the environment that washes over us and determines much more than our genes ever will.”
Propaganda 101: The False Dichotomy
The above (and below) quote is from a blog post, ‘Secrets to Health are in Diet and Lifestyle Not Human Genome: The Failure of Decoding the Human Genome and the Future of Medicine‘ [it actually starts with “Secretes”, but I assume that’s a typo], by Dr. Mark Hyman. There is some value here, but when I’m being offered “secrets to health” and instead given fluffy science, appeals to intuitive folk psychology, and hyperbole, I have a hard time recommending you endeavor to dig for nuggets of truth. The way the article is framed is misleading, and… well… wrong. It’s not wrong to say that epigenomics is real and important, but it is wrong to dismiss genetics in favor of epigenomics. That approach is not only a logical fallacy, but an advertising/propaganda tactic. Claims along these lines are madness when we consider that all epigenomics can ever do – by its own definition – is influence the expression of genes. Knowing this simple fact refutes the sensationalist claim that, “Science is now proving [that] the environment… determines much more than our genes ever will.” [emphasis mine]
So at first I was put off by the article. But that was before I remembered that I’ve recently been working on a theory proposing that, while beneficial to plants via chlorophyll, our yellow sun presents a contra-optimal environmental input to epidermal vitamin D synthesis. If we were able to find suitable habitat on a planet orbiting a red sun, the spectrum phase-shift would cause a hormone balance reconstituentialization switching the protein cascade of certain genes to unlock the potential for conscious human negation of both gravity and friction. Failing that, I have high hopes for the venom of radioactive spiders.
Now… if I actually believed in the Superman or Spiderman hypotheses, statements similar to those made by Dr. Hyman would enable their theoretic viability.
The Epigenome: Bypassing Darwin and Evolution
More important than our collection of genes, it now appears, is how those genes are controlled by both internal and external factors—our thoughts, stress, social connections, what we eat, our level of physical and mental activity, and our exposure to microbes and environmental toxins. These factors are switches that turn genes on and off and determine which proteins are expressed. The expressed proteins, in turn, trigger signals of disease or health.
In the context of this article, the claim that epigenomics bypasses Darwin and evolution seems to be more of a political hope than a scientifically defensible position. Now everybody, in your best Beach Boys harmony:
Wouldn’t it be nice if genes were over
‘Cause selling magic-bullets never would be wrong
And wouldn’t it be nice to live forever
In worlds where supra-malleable human beings belong
No, I am not saying Dr. Hyman made this argument explicitly. Yes, I am saying the implication of the argument unlocks false hope in a world in which epigenomic influences wield supreme power. Invoking the concept of control by external factors is problematic. It implies that, if only we can find the right environmental factor(s), we can positively or negatively bend genetic expression to overcome any malady or limitation. If genes and/or evolution don’t matter, nothing can stop us, comrades!
Yes folks, I regret to inform you that it’s the “nurture trumps nature” argument all over again. Not only is the mind a blank slate (as others claim) in this warm and fuzzy world, but now the body is as well. Bla bla fracking bla.
It could be rightly said that I’m attributing more weight to Dr. Hyman’s mention of epigenomics than is appropriate. However, the other factors he discusses (exposomics, nutrigenomics and microbiomics, and toxigenomics) fall under my same criticism asserting an interactionist framework. In fact, while trumpeting the “failure” of genomics, he simultaneously admits “the dynamic interplay of the environment” and genes. Nutrients, microbes, toxins, and (catch-all term) exposomes all collide with the human genotype and phenotype in ways that can’t accurately be cast in a binary light in which genomics has been deemed a failure. And despite the equivocations and qualifications invoked to temper his message to be mostly accurate-ish, there’s no hope of escaping Darwin and evolution in Dr. Hyman’s position.
Three neo-Darwinist points about epigenetic switches
*Note the switch from “epigenomics” to “epigenetics”. For our purposes, epigenomics can sufficiently be thought of as a macro view of epigenetics.
As is always the case in the “nature vs. nurture debate”, there is no “nature vs. nurture debate”. The false dichotomy only exists in the polemical propaganda of the nurture Nazis (think Seinfeld’s “Soup Nazi”, not reductio ad Hitlerum). No, there is no versus, there is only synthesis amidst a continuum. The 3 points below are from Oana Carja‘s excellent answer to the question, “Is it time to revise evolutionary biology textbooks to reconcile Darwin with Lamarck?” They have been edited, but the two quoted paragraphs that follow appear in their original form:
1. A property of the DNA sequence itself is the ability to switch epigenetic state, and is therefore subject to natural selection on conventional mutations.
2. Natural selection will eliminate switches with maladaptive eﬀects but perpetuate, and reﬁne, those with adaptive eﬀects.
3. The additional ‘information’ represented by a DNA sequence’s particular epigenetic state is repeatedly being reset.
Thus, epigenetic switches do not involve cumulative, open-ended evolutionary change. Switches are wonderful tools that increase the options available to DNA sequences but, in themselves, should not challenge the beliefs of a neo-Darwinist. The high rate of epigenetic change is also important because the level of achievable adaptive precision is limited by the fidelity of replication. Adaptation is constantly being degraded by copying errors and the higher the rate of errors, the larger the selective advantage that is required to maintain previous adaptation. Thus, small selective advantages are unable to be maintained in the presence of low-fidelity replication.
Therefore, significant adaptations are expected to be encoded genetically rather than epigenetically. Modern neo-Darwinists do not deny that epigenetic mechanisms play an important role during development nor do they deny that these mechanisms enable a variety of adaptive responses to the environment. Recurrent, predictable changes of epigenetic state provide a useful set of switches that allow genetically identical cells to acquire diﬀerentiated functions and allow facultative responses of a genotype to environmental changes (provided that ‘similar’ changes have occurred repeatedly in the past). However, most neo-Darwinists would claim that the ability to adaptively switch epigenetic state is a property of the DNA sequence (in the sense that alternative sequences would show diﬀerent switching behavior) and that any increase of adaptedness in the system has come about by a process of natural selection.
In other words, epigenetic switches themselves are subject to evolution. Thus, I must sincerely apologize for my current inability to christen epigenetics as the long-awaited mechanism to bring the DC vs. Marvel debate into the scientific realm.
The astute among us may have realized by now that my criticism of Dr. Hyman’s article relies almost entirely on just four of his words. If “failure” wasn’t in the title, and “control” wasn’t used in reference to extra-genomic influence, and “bypassed” didn’t precede Darwin and evolution, and “determines” wasn’t attributed to epigenetic influence, I may not have been forced to write this. In actuality, those four little words poison an otherwise interesting article in a way that misleads casual readers. I’ll just put aside the problems with the use of “much more” in the lead quote unless someone raises further concern in the comments.
Epigenetics is interesting. Epigenetics is useful. However, epigenetic influence remains confined by genetic potential and Darwinian selection. Let us not make it out to be the panacea it is not. Beyond that, I believe we’re at, or even beyond, the point at which there needs to be some push-back on pop science framings of epigenetics as something that somehow undermines neo-Darwinian evolution. From a strategic perspective, misconstrued epigenetics can be taken out of context far too conveniently by the Creationist and/or Intelligent Design programs.
Oh, and for those of the paleo persuasion… Dr. Hyman’s prescription for gut health? “Eat whole unprocessed foods with plenty of fiber… beans… and whole grains.” Beans and whole grains for gut health!? I don’t feel bad about picking on this article for four words after all. Please don’t take that as ad hominem; it supports the thoughts in the preface.