Note: This post is essentially “what we talk about when we talk about genetics.” If you want a more straightforward scientific rebuttal of the recent Bioscience Resource Project essay arguing that genes have little to no effect on who we are, go here, or, better yet, here, here, here, here, here, or here (last link in Italian).
Michael Pollan, the well-known writer on food and agriculture, is a smart guy. His arguments tend to be nuanced and grounded in common sense. I like his basic maxim on nutrition – “Eat food. Not too much. Mostly plants” – so much that I recently promoted it in a Newsweek cover story. He’s the last person I’d suspect of reactionary thinking, which is why I wish I didn’t have to say this: Michael Pollan has made a deeply unfortunate mistake.
A few days ago, speaking to his 43,000 followers on Twitter, Pollan linked to an essay written by an environmental advocacy group that spends much of its time fighting the depradations of Big Agriculture. Curiously, the essay wasn’t about ecological destruction or even about agriculture. It was about human genetics. It argued that since genetics currently can’t explain everything about inheritance, genes must not influence the development of disease, and thus the causes of illness must be overwhelmingly environmental (meaning “uninherited” as opposed to “caused by pollution,” though the latter category of factors is part of the former one). This was a little like arguing that your engine doesn’t power your car because sometimes it breaks down in a way that confuses your mechanic — and concluding that gasoline alone is sufficient to make a car with no engine run. But Pollan took the argument at face value. He said it showed “how the gene-disease paradigm appears to be collapsing.” He was troubled that its contentions apparently had gone unnoticed: “Why aren’t we hearing about this?!”
Perhaps unknown to Pollan, the human genetics community – or at least the small, vocal part of it that is on Twitter – had in fact heard about this. It set about dismantling and dismissing the essay’s chief conclusions, which were at best overstated and at worst flatly wrong. A number of people outside the genetics community also must have seen the essay. Maybe some of them read it and thought, “huh. My kid looks just like me, but these people are saying genotype has little to no effect on phenotype. Do they really think my kid has my distinctive Roman nose because he grew up in my house?” Maybe some of them wisely thought, “hmm, I was taught that nature and nurture both mattered, this can’t be right” — i.e., don’t you need the engine and the gasoline? — and moved on.
But Pollan’s tweet lent the essay prominence and credibility. Since then, the Huffington Post has jumped on the meme, declaring with typical flair that genomics may just be “one part boondoggle, one part conspiracy by the military-industrial establishment.” The very respectable Marion Nestle has also joined in, tweeting enthusiastically about the “study,” which is no such thing. (It’s an opinion piece on a website, just like this blog post.) Who knows how many people have now seen the essay and been misled into thinking that science has shown the “environment must be the entire cause of ill health?” Who knows how many people far too savvy to subscribe to genetic determinism are now espousing “environmental determinism?”
It’s been more than a week since Pollan’s tweet – which, in Internet time, is an epoch – and he’s said nothing else about the topic. The essay is probably fading away. But I fear the thinking behind it isn’t going anywhere. This looks to me like the first (or maybe the second) flare-up in what may be a new iteration of the nature-nurture debate, which scientists abandoned decades ago as a false dichotomy but which apparently has never disappeared from popular imagination. It’s an iteration in which both sides will speak the language of science but only one will hew to its principles – a debate that could quickly come to resemble the “controversies” over autism/MMR and intelligent design. It will probably center on the issue of missing heritability, which is complicated and messy and lends itself to abuse. And if it does come to pass – if this essay is not an anomaly but a harbinger – it’s going to involve a whole lot of woo.
Well-crafted woo, at that. The argument in the essay – which boils down to “genetics is a work in progress, therefore genes don’t matter” – appeals to many people’s desire to focus on what can be changed (environmental factors) as opposed to what can’t (one’s genetic sequence). It slyly paints geneticists — and indeed, “medical researchers” in toto — as determinists, despite the fact that it’s practically impossible to be a determinist if you work on complex-trait inheritance, as Dan MacArthur has observed. It’s aimed at well-educated people who are naturally suspicious of the “military-industrial complex,” and people who have never had any particular reason to learn how heritability is calculated because they’re busy doing other important things. And it’s counterintuitive and anti-authoritarian in an extremist but oddly appealing way, one that sounds so populist as to resemble the rhetoric of both the Huffington Post and the Tea Party (“all those big-deal geneticists are WRONG!”).
This type of argument could present an enormous challenge for human geneticists, putting them on the defensive for research that should not need defending — and doing so in a way that’s very hard to counter without coming across badly. Sneering at denialists doesn’t work. It only feeds their momentum (“all those big-deal geneticists are SNOBS!”). Calmly explaining the facts doesn’t always work, either, as vaccination advocates and evolutionary biologists have learned over the years.
Last Thursday, I tried to put together a rebuttal of the essay as part of a 15-minute crash course in the basics of human genetics and genomics. After I gave the talk, I put it on the web. (I’m not sure it worked and would appreciate feedback. Also, it cuts off abruptly at the end because I forgot to ask people if it was OK to include the Q&A period and because YouTube doesn’t like videos longer than 15 minutes.) The presentation discusses GWAS design and heritability, present and missing. It touches very briefly on some directions for future genetic research: rare/less-common variants, copy number variants, gene-gene interaction, gene-environment interaction, etc. It considers how much the “missing heritability” debate will matter in the long run. And it does a wee bit of fact-checking the essay, albeit mostly by citing other people’s arguments.
But I don’t expect all that many laypeople, save my captive audience from last Thursday, to pay attention to the point-by-point part of the rebuttal. Who outside the field has the time or will to burrow so deeply into statistical genetics methodology when there are jobs to be done, kids to be raised, lives to be lived?
What I do want people to see is the 10:55 mark, where I try to engage with the essay on a level that doesn’t require any understanding of genomics — because I think this may be a way of explaining what’s wrong with it that speaks to a wider readership. Aside from its factual misinterpretations, the essay makes two logical errors that anyone can see if he looks hard enough:
1. It assumes that absence of evidence is evidence of absence, concluding that because common diseases aren’t caused by a handful of genes with strong effects, they aren’t influenced by genes at all. This is clearly a silly position, but it’s a handy one if you are, say, a group that wants to raise the profile of biomedical research into non-genetic factors such as pollution, and if you’re concerned about money being poured into genetic research at your expense. (For the record, I agree that research into environmental factors is important. Maybe the essay’s authors and geneticists should be lobbying together against pending cuts to the NIH? To borrow a malapropism from someone with whom I disagree on almost every other point: shouldn’t we make the pie higher?)
2. It mistakenly portrays science as a monologue, and a dull one at that. First, it lists some of the potential hiding places for heritability that remain in the genome. Then it notes that a few scientists think some of them are less likely candidates than others and that there’s no consensus that one of them will explain everything. This is presented as evidence that almost all of human genetics is in crisis. But the data has just begun to be generated, and of course it’s unlikely that one type of factor will explain everything. Life, in biology as elsewhere, is complicated. (As geneticists freely point out: take it from David Altshuler, Leonid Kruglyak, and a bunch of other people who would know.) We’ve seen this line of “minor disagreement = major crisis” argument before, from creationists who conscripted Stephen Jay Gould and punctuated equilibrium as “evidence” that natural selection wasn’t a widely accepted principle. It was just as absurd — and effective — a rhetorical tactic then as it is now.
Why do I think these parts of the rebuttal are the most important ones? Because if this essay is indeed the first volley from a new, “environmental determinist” movement, the technical flaws it contains are not going to matter in terms of public opinion. Laypeople aren’t going to have the time to learn the nitty-gritty details of how genomic research is done, and they will react poorly to anything they perceive as condescension from geneticists. As they should: Condescension is bad.
But ultimately, the essay itself — really, the entire “genes don’t matter” argument — is what’s condescending. It starts from a couple of philosophically flawed premises, papers over the holes with something that looks and sounds like science, and assumes that its readers, lacking technical expertise, are unable to see that the conclusions are not reality-based.
Call me an optimist, but I think many readers are smarter than that. And if I were a typical reader — if I weren’t closely acquainted with the scientific literature — I’d be angry to find that people purporting to enlighten me were in fact trying to snow me. (“Hey, this environmental-determinist advocacy group is WRONG!”) Or at least I’d want someone I respected — someone with, say, 43,000 followers on Twitter — to set things right.
Here’s a suggestion for how to do that in fewer than 140 characters: “Genes matter. Not too much. So does the environment.” Over to you, Mr. Pollan.