Yet another journalist seems to have fallen for the epigenetics mavens: those revisionists who think that a form of Lamarckian inheritance can be important in evolution. These people claim that the environment itself directly changes the DNA, not by altering the sequences of bases, but by somehow placing methyl groups on some of the DNA bases (“methylation”). Such changes can be passed on to the next generation, and so the revisionists (aka “careerists”) argue that the inherited epigenetic changes could be subject to natural selection, leading to a form of evolutionary change that is, roughly, the inheritance of acquired characters.
In a new piece on Big Think,”How about a new theory of evolution with less natural selection?“, journalist Robby Berman pushes this idea, noting that it was a big part of the recent Royal Society conference on “New Trends in Evolutionary Biology: Biological, Philosophical, and Social Science Perspectives.” (I discussed the problems with this conference’s proposals here.)
Among the problems with seeing environmentally acquired epigenetic changes as an important cause of adaptation—problems that I’ve discussed ad nauseam—are the following:
- Virtually all epigenetic markers are wiped clean as the DNA goes through gamete formation, and wiped clean within a few generations after they arise. Such changes cannot serve as a basis for permanent adaptation, which is what the epigenetics mavens claim.
- There is little evidence for environmentally induced epigenetic changes in vertebrates, an observation relevant to the article under discussion.
- When geneticists are able to map adaptive changes in the genome using crosses and DNA sequencing, they invariably show changes in the base sequence of DNA, not to methylation of those bases.
- If some DNA base sequences are more liable to environmentally-induced methylation themselves, and those methylated changes are adaptive, then the susceptible DNA base sequences will increase in frequency. But this is straight natural selection on the DNA, not a drastic revision of how natural selection works.
- Some methylation changes are coded by the DNA: DNA bases that say to the genome “put methyl groups on bases X, Y, and Z”, and that form of methylation can be adaptive, for example in mediating parent-offspring conflict. But this form of evolution is not not induced by the environment; rather, it’s coded in the genome itself, and evolves via conventional natural selection (i.e., mutations that change the DNA sequence in an adaptive way become more frequent.)
We still have not a single instance of adaptive evolutionary change arising via environmental, epigenetic modification of the DNA, and yet people are still talking as if it’s a serious difficulty for modern evolutionary theory. Well, when you show me a dozen cases of it, then we’ll talk. In the meantime, the rest is simply unfounded speculations issued by ambitious evolutionists.
And such speculation is rife in Berman’s Big Think piece. (I’m starting to think that not a lot of thought goes into some of the Big Thinks.) First of all, though admitting there are detractors, Berman accepts epigenetics as a major challenge to evolutionary theory. It isn’t—at least until we get some data. Second, he raises the idea that human agriculture, of all things, is a genetic adaptation that arose through environmental modification of the DNA. Get a load of this:
Still, epigeneticists hope the field can help explain evolutionary changes that don’t seem to be accounted for by modern evolutionary synthesis.
For example, speaking at the Royal Society was Melinda Zeder, who talked about the way in which modern synthesis fails to provide a reason for mankind’s turning to agriculture 10,00 years ago and its ensuing evolutionary impact. Growing crops may have taken years, so there could not have been a short-term evolutionary benefit to it. As Zeder told Quanta, “You don’t get the immediate gratification of grabbing some food and putting it in your mouth.” It’s also been theorized that a climate shift caused agriculture to bloom, but there’s no evidence of such a shift.
Zeder suggests we take a different view of humans at the time as creative individuals who deliberately decided to change their environment by farming, pushing human evolution in that new direction. This process is called “niche construction,” and it’s more than just a human behavior; think beavers and their dams.
First of all, Berman doesn’t seem to realize that “niche construction”—the idea that organisms, by their behavior, can change their environment in a way that affects their future evolution—is not the same thing as epigenetics. Niche construction involves perfectly normal adaptive changes in the DNA that are not induced by the environment, but simply adapt the organism to a novel environment it encounters due to a change in behavior or physiology (and those changes themselves, like leaving the water for the land, could have resulted from conventional natural selection).
Berman has no idea what he’s talking about here.
But that aside, can epigenetics explain agriculture? Why do we assume, as both Zeder and Berman seem to have done, that growing crops is coded in the human genome? It seems much more likely that it’s a cultural adaptation: something useful figured out by our ancestors and then passed on by learning. If humans were raised in an environment without having any access to such learning, would their genes tell these naive people to put seeds into the ground? I doubt it! There’s no need to explain agriculture as a genetic change, much less a Lamarckian, epigenetic change.
Nor do we have to invoke a climate shift as the impetus for agriculture. All we need to happen is for someone to discard seeds and see that useful plants grew from them. Or to have someone pick some useful plants and realize that they could be propagated from shoots or seeds.
Finally, it often takes less than a year to grow a crop, so why does Berman repeat the idea that “growing crops may have taken years.” It may have taken years to refine agriculture, but not to get it started.
This is what we call abysmal scientific journalism. But does Berman know any science? His Big Think bio describes him like this:
I’m a writer, musician, and father living in the very upper Midwest with my wife, two daughters, three cats, and countless questions. I’m especially interested in animal rights, creativity, politics, the nature of things and time, and in making a worthwhile contribution. You can follow me @everyrobby.
Well, good about the cats, but this doesn’t show much training in science. Now I don’t often go after people for lacking formal sceintific credentials, but when someone fails as spectacularly as Berman, one might pin the blame on his lack of scientific training. At any rate, the Big Think has created a Big Stink, making naive readers think that epigenetics is not only a novel and important source of evolutionary change, but one responsible for a cultural shift—agriculture—that might not even be a genetic adaptation.
Woe is me! Or, as the landsman says, “Oy vey!”
I’ve always kind of assumed that agriculture likely arose as a cultural practice after some clever ancestor noticed crops growing where the tribe had been going; i.e. from their own feces. Upon noticing that the seeds he’d eaten in the fall were now fruits in the spring, he managed a causal connection, leading to his collecting and planting seeds purposely.
There is archaeological evidence that many ancient hunter-gatherer peoples gathered wild grains of various sorts for a long time before the advent of agriculture. What evidence there is makes it look more like a gradual transition from gathering wild grains, to gathering them from regular areas, to cultivating them in simple ways in small areas and then moving on to larger scales and better organization.
Whether agriculture enabled more people living together or vice versa? My guess would be the two were mutually enabling.
Yeah, that was a weird assumption on their part. A sedentary lifestyle and domestication of plants and animals kind of go hand in hand; each makes the other easier. Since being sedentary has some sociological advantages (constant access to a water or other resource; you can build defensive fortifications, etc.), it seems perfectly reasonable to hypothesize that plant domestication and human gardening/growing behavior was primarily a sociological phenomenon, no any sort of inherent biological drive.
Or, “we’re stuck here for a while, what do we eat?” “This tough thing again for dinner, mom?” Grains are hard to imagine getting started eating. Desperation, I think, in our case – like the first one to eat a (raw) egg.
The epigenetics is BS, but cultural evolution is, it seems to me, Lamarckian. It subsumes and replaces biological evolution on a far more rapid time scale. We’re well into it, for better or worse.
IIRC, Gould used this comparison back in the ’80s or ’90s. Its kind of the bio equivalent of “that’s not a knife…,this is a knife.” You want to see what inheritance of acquired characteristics is really like? It isn’t some wimpy meth group being passed on; its the entire German state working to kill milllions of people out of perceived social undesirability. Its also a 10x decrease in infant mortality in 80 years (I thought we could use both a good and bad example of what it can do). Actual Lamarckian evolution would be so much more fast and profound compared to Darwinian evolution that it would look nothing like it. IMO its fair to say that if you have to look at the statistical margins to figure out whether it’s occurring, it probably isn’t occurring. Because if it was, the effect wouldn’t be small.
I do not think epigenetics qualifies as BS because I do not even know what epigenetics is. Putting aside PCC(e)’s correct usage of the term, “epigenetics” is on its way to being like “energy” – i.e. meaning whatever the writer or speaker wants it to mean.
Yes, but it adds nothing to say that cultural evolution is Lamarckian, and in fact confuses people, since Lamarck’s theory was one of genetic rather than cultural heredity. It’s just best to call it cultural inheritance or, better, “learning.”
And these people are making epigenetics sound a lot like pseudoscience. It is high time that evolutionary law be taught as early as possible.
“It is high time that evolutionary law be taught as early as possible.”
My idea for middle school biology course is to introduce evolution in the 3rd lesson, together with the terms individual, species and development. (1st lesson introduces life, 2nd lesson – the cell.) I have even made a page, with an illustration on equid evolution:
https://mayamarkov.wordpress.com/2008/01/22/individ_vid_i_razvitieto_im/
However, reading it requires hard work with Google Translate.
I💖you!!
Thank you!
I take your point, but by Lamarkian I meant only inheritance of acquired characteristics. Memes in the broadest sense. I didn’t intend to give the old man credit! 🙂
The idea that epigenetics is a mechanism behind a Lamarckian evolution is indeed problematic. We don’t have evidence for Lamarckian evolution; therefore, logically, looking for mechanisms behind it are absurd. Moreover, as was already noted by the OP, we even have little evidence for epigenetic modifications passing on to more than one generation.
However, epigenetics itself is no BS. It is an umbrella term for several biological phenomena, which can be experimentally measured with reasonably high certainty. It is hypothesized that epigenetic modifications is one of the mechanisms by which environment affects cellular phenotypes (this hypothesis is currently being tested for all possible sorts of environmental exposures, and causal inference here is a major problem that will also be solved soon).
It is important to point out that this hypothesis does not oppose Darwinian evolutionary theory in the slightest.
What worries me most is that this purely scientific phenomena is getting utilized by ideologues of all sorts, from religious right to Marxist left, and this in turn puts an undeservedly bad mark on people who study epigenetics for a living.
In terms of ‘philosophy of science’, I don’t think this is right at all. One of the most normal and natural things to do when developing a new hypothesis is to try and figure out mechanistically how your hypothesis might work. You don’t need to go observe it working before you do that sort of gedankenexperiment. In fact, doing that ‘in theory’ working-out can be good science, as developing a hypothesized mechanism for your new hypothesized effect can help ensure your idea is testable.
You see the same position offered in regards to religion. I.e., theists should demonstrate there is a god before talking about its possible qualities. Well, no, that procession is not necessary and it isn’t a mark against theists if they don’t do things in that order. In fact, doing things in the reverse order can make a lot of pragmatic sense because it means we spend less time and resources on snipe hunts. Tell me the properties of your hypothetical god, and I may be able to tell you whether its a testable idea, whether you’ve got a logically contradictory set of properties, etc, and do a lot of similar analysis. That can happen “at the desktop”, eliminating the need for anyone to spend time or money to go look for your hypothesized entity.
I agree with this in principle, but I dare say it has already been done. That’s how Peter Vushev knows that there is no evidence that it occurs.
I saw this article in my e-mail feed as well. It look like he extracted key parts about the meeting from Zimmers’ very balanced review of the meeting, but tellingly, he did not mention the rest of what Zimmer reported, which was on the opinions that the Modern Synthesis is doing just fine, thankyouverymuch.
This addresses Terry Salkin’s theory of environmental factors becoming part of evolutionary changes and how wrong the thinking is— Especially read about Robby Berman at the end of the article
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The writer seems terribly confused. I think he just mashed together two different ideas that were discussed at the conference, epigenetics and cultural evolution, without realizing they have nothing to do with each other.
Isn’t the origin of agriculture fairly well correlated with climate changes, such as the end of the Younger Dryas? Or am I wrong in thinking that?
Speaking of science “journalism”, there’s an article by one of the greats, Elizabeth Pennisi, in the new issue of Science that hypes hybridization to show that everything we thought we knew about evolution was wrong, wrong, wrong.
I think it’s probably a learned behavior on my part to not form opinions without the aid of experts about things I know very little about because I have no training, but I don’t know if I’m right because I have no formal education in evolution, behaviorism or sociology. I only know what I’ve gleaned from listening and reading. Why would anyone pay any attention to me if I began to share my opinions regarding the origin of agriculture? Perhaps Mr. Berman could share some information about the “very upper Midwest” so I can learn about it from him.
As a person with no scientific credentials myself, I have no problem going after another person just like me who keeps telling me things he knows nothing about. Perhaps he thinks the stuff he knows about is boring.
Maybe there is no such thing as stuff he knows about.
You may be right,. but how would I know?
“There’s no need to explain agriculture as a genetic change…”
I fully agree. However, I started thinking whether there is genetic change associated with agriculture, the way animal husbandry led to lactase persistence. While gathering is similar to agriculture, hunting isn’t. Agricultural laborers, compared to hunters, need not be so fast runners, but must be able to endure continuous hard work. Has anyone come across any research on this?
There has been a LOT of research on the effects of agriculture on human evolution. I’ve no idea how much of it is solid though.
Recently I’ve read about the poor fit of modern human teeth to jaw is driven by the selection pressure of an agricultural lifestyle: “Before Agriculture, Human Jaws Were a Perfect Fit for Human Teeth” [Smithsonian] & also an article on the reduction in bone mass & bone strength of agriculturalist humans compared with hunter gatherers
I’ve often wondered what is a reasonable timescale for investigating human evolution – there’s a lot going on in the environment we’re creating today that must eventually effect our evolutionary path in a way that can’t settle back to a mean if it persists. Everything from novel foods, novel pollutants to digital tech – but then one bad natural event could reintroduce the sort of selection that favours humans that are fittest for hunter gathering…
I hear this “sudden advent of agriculture 10,000 years ago” trotted out a lot, and often as a “sudden change in consciousness” as if at midnight on January 1st 7999 BCE humans started planting seeds, wearing clothes and building communities. Much like the Cambrian “explosion” that occured over the course of millions of years, the “sudden” here is relative and took something like hundreds and thousands of years, at least since we really started leaving behind artifacts, to develop. The last two hundred years has been a much more dramatic explosion than the 10,000 to 100,000 years before it, but no extreme or even mystical explanations are needed to explain that.
A few years ago I went to see the comedian Rob Newman doing a stand-up show called ‘A New Theory of Evolution’, in which he argued a) that Richard Dawkins believed human beings are naturally selfish because of their genes and b) that Dawkins knew nothing of the way epigenetics allowed for altruistic behaviour. I sent him a polite email explaining how, although there were funny bits in the show, he had misunderstood Dawkins (in fact I’m not convinced he’d ever actually read anything by Dawkins); but he never replied. What was interesting, though, was the strategic way ‘epigenetics’ was used – clearly Newman had very little idea what epigenetics actually is, but he thought it was a convenient tool to use against biologists whom he suspected of having the wrong ideology.
Why they don’t consider that a lot of characteristics that we see/ observe might be byproduct of other adaptations?
I have often found that “science writers” get things wrong. Being particularly interested in physics (Relativity,Quantum Mechanics etc) I have a lot of books by trained scientists written for the layperson. ( I am still a rank amateur with no training) If a person doesn’t have reference books to check articles written by a “science writer” all kinds of disinformation is spread. Not good
I fear this epigenetics business will take several generations to be bred out.
+1 !
😀
Good point. Some Science Journalism seems about as reality based as Scientific Creationism. We are fortunate to have science writers like Carl Zimmer, Ed Yong, and others of their caliber sharp enough to see through controversies (and pseudo-controversies) and talented enough to inform knowledgeable readers what they have seen.
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Your point about the lack of adaptive epigenetic change needs emphasis. In the cases where epigenetic change has been argued, the effect of an environmental effect such as famine has not been to make an epigenetic change that adapts you to that environment. Instead, it increases the rate of heart disease or cancer — not much help in dealing with the environment!
If adaptive changes are found, they will be accidental — most epigenetic changes will not be adaptive.
I’m guessing that Berman was raised in a city? You can find plants outdoors, lift them up, and put them down near your house.
“Epigenetics” is becoming the new “quantum” for sure … 🙁
Now, what can we do to blanket the popular press with good information on this topic?
DNA methylation is ill suited to work as a unit of long term inhertiance as atleast vertebrate CpGs have a pesky habit of being lost over evolutionary time due to deamination to T/U depending on methylation status. Why the CpG dinucletide is strongly underrepresented in e.g. the human genome.
Could atc as a short term memory laid down during fetal development and maybe even passed on maternally to subsequent generations through similar in utero priming but haven’t seen a single example..