Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
This is beautiful. Guess what? Dictionaries understand dictionaries.
By the way, the @smarick fellow seems to be taking this smack upside the head in good grace, but it’s amazing to me how many people are furious at the notion of using “they” as a singular pronoun.
Larry Moran rips into the latest hype over epigenetics. Good. There is some valuable biology buried in the field, but I see so much nonsense that even as a developmental biologist who wants to seem more attention to regulative changes in the genome, I’m just seeing so much exaggeration that I think it is doing more harm to our understanding than good (see also Carl Zimmer’s latest discussion of epigenetic over-reach). But this video is just too much.
It’s true — region of the genome can be switched on or off in a coarse way by chemical modification of DNA and associated proteins. It happens all the time. But as Larry points out, this doesn’t just happen by magic. There are regulatory factors that change patterns of gene expression, and they’re probably most responsible as well for triggering the establishment of epigenetic marks.
But here’s my objection: the hype seems to be ignoring development (I know, unforgivable). The problem with assigning too much importance to the inheritance of epigenetic marks is that individual cells and tissues acquire them throughout development and even adulthood…but they don’t matter genetically. Have the proponents never heard of Weismann’s Barrier? Changes in the somatic tissues don’t propagate to the next generation. All that matters are changes in a subset of cells in the gonads, the testes and ovaries. So we’re already dealing with a tiny fraction of our cells that also have unique tissue-specific epigenetic marks, and more importantly, their own specialized patterns of gene regulation.
Then, further, gene expression in the germ line is further refined during maturation of the egg and sperm — both of these cell types are highly specialized and gene expression is honed even more during their development. It’s nice to dream that epigenetics influences neurons in the brain, but you’re not going to inseminate anyone with your neurons, nor are those cells going to migrate down into your ovaries and pass their history on to the next generation.
The video does mention that most epigenetic marks are going to be cleared during gamete formation, and other germ-line-specific marks added, but it just blithely slides past that. It seems to me that the clearest example of epigenetic modification in inheritance is genomic imprinting, which is a consequence of differential gamete-specific modification of sperm and egg, and its main effect is in regulating gene dosage.
It’s strange. I don’t even see the appeal of these epigenetic fairy tales; I certainly don’t see any problem in evolutionary theory that requires patching up with this kind of phenomenon. But Larry includes an excerpt from an interview with the creator of the video, and suddenly all is clear. This bastardized, exaggerated version of epigenetics appeals to people who are uncomfortable with the whole central idea of modern evolutionary theory — who dislike seeing gene transmission uncoupled from the will of the individual.
I came from the world of evolutionary biology. I have always been interested in evolutionary theory but I was never convinced by the neo-Darwinian argument that environmental factors are not a big player in the generation of genetic changes. On the other hand, I never understood the fierce dismissal and often mocking of the Lamarckian ideas in schools and universities; particularly, because Darwin himself never denied Lamarck’s ideas. In epigenetics I found the mechanisms that allow you to understand the action of environmental exposures on the genome.
Whoa. That environmental factors are not a big player in the generation of genetic changes
is sort of true; the environment can influence the rate of genetic changes, but doesn’t play a big role in shaping the direction of that change — that’s all a consequence of changing the frequency of representation of those changes in the population. That he brings up the idea of Lamarck is telling. Lamarckian evolution ain’t coming back, although it’s surprising how often people want it.
Also, Darwin himself never denied Lamarck’s ideas
? Does he know nothing about the history of evolutionary theory? Darwin did not deny them, because his theory of inheritance was all about the inheritance of acquired characters and pangenesis, the generation of a gamete by contributions from all tissues (which, come to think of it, is what you’d need for the epigenetics hype to have any hope of working). He was pre-Mendelian genetics. He was wrong. You can’t defend Lamarck by citing a guy, no matter how influential, who had no viable theory of genetics, and who wrote in the era just before genetics was explored and understood. He might as well support it by announcing that Aristotle didn’t deny Lamarck.
As for the idea that epigenetics somehow explains the effects of environmental exposure to damaging agents…I’m trying to think of any clear examples of how that occurs, and I’m a developmental biologist who has been studying teratology for a few decades. We don’t invoke epigenetics to account for abnormal cell death, or signaling failures, or mismigration, or endocrine disruption, or any of the phenomena that are commonly responsible for non-genetic errors in development. His example is to claim that exposure to DDT in the 50s and 60s somehow led to the current high frequency of obesity.
He’s got no evidence. He has no mechanism, other than to say, “epigenetics!”
The thing to watch out for next is revealed at about 4:00 in the video, where he talks about using diet and behavior to give yourself a “healthy epigenome”, whatever that is. I’m sure some unscrupulous, dishonest someone, somewhere is writing a diet book about super-foods to super-charge your epigenome for you and your baby.
I’m calling it. There are already plenty of pseudoscientific books that mangle the concept of epigenetics. I’m sure the ones that will turn it into a marketing fad are coming up soon. We’ve already got a lot of books touting the microbiome as the cure-all for everything — I can easily imagine the fusion of the epigenome and microbiome hype machines popping up on Amazon.
Can I claim royalties for predicting it?
I know, it’s hard, what with all the fireworks around here, but there’s a lesson to be learned.
After the Brexit vote, Boris Johnson resigned.
And now, another architect of the catastrophe, Nigel Farage, has stepped down.
I have to give them some credit for recognizing, after the fact, what a disaster they have engineered, but they get no respect at all for running away like cowards from the hot flaming mess they made.
Please, America, remember this: bullying, bigoted ignoramuses will disintegrate at the first hint of opposition. Keep that in mind until at least November, OK?
Oh, who am I kidding. This is an electorate with the attention span of a jellyfish.
I grew up with the Vietnam war in the background. It wasn’t the hippies, or the protests, or the myth of people spitting on returning veterans that made me doubt my country: it was the National Guard raising their guns and firing into a crowd of students at Kent State. It was a duplicitous Richard Nixon resigning in disgrace. It was Henry Kissinger committing war crimes and being rewarded for it.
The Iranian hostage crisis was the dominant news item when I went off to college. It was wrong, and Iran’s descent into theocracy was a catastrophe. But what troubled me was my country’s long support for the tyrannical Shah of Iran, which had led to this crisis, the way Ronald Reagan stole credit for its resolution, and how that administration smoothly segued into total corruption, trading arms (can we stop doing that?) to Iran to shuffle money under the table to murderous right-wing killers in Nicaragua. It was Oliver North becoming the ‘brave’ face of American policy.
I’ve read the sanitized propaganda we’re given in public schools, and at the same time read the more complex histories. I hear about courageous pioneers bringing civilization west, and I read about Jeffrey Amherst and his genocidal plans, the rabble-rousing hatred that led to the massacre at Wounded Knee — and by the way, did you know that 20 medals of ‘honor’ were awarded for the murder of men, women (excuse me, ‘squaws’: wouldn’t want to humanize them), and children in that event? I lose all respect for the concept of honor. I am instructed in the heroics of the Civil War, and no one explains that the seeds of that brutality were sown in the cowardice of our noble Founding Fathers, who could talk a good game about liberty but but shied away from doing anything that might cost them some property, the human beings they owned as slaves. I had to learn on my own that we whipped around from a war to emancipate the slaves to an era of Manifest Destiny, in which plutocrats declared that they had a right to the lands of uncivilized yellow and brown people.
All my life I’ve been watching fools, criminals, and villains wrapping themselves up in their loud patriotism and being lauded for it. Do you wonder that I find flag and country tainted? Are you surprised that I find little cause to celebrate today? Do you think it’s all the fault of godless commies and leftie lies? No. It’s because the people who most thoroughly embrace that unthinking love of country do not love it for the high-minded principles stated at its founding: liberty and justice are nothing but words. They don’t love it for its past openness to immigrants; we no longer lift the lamp beside the golden door, we’re gonna build a Wall. Our Constitution isn’t about protecting our rights or guaranteeing equality, it’s about making sure every one gets to own as many guns as they want.
I’m feeling a bit dismal this morning, thanks to some petty and entirely trivial interactions, and then I read this–an eyewitness account of female genital mutilation in Kenya. I won’t describe it, except to say…old blind woman with a razor blade, no anesthetic, swarm of women holding the victim down and silencing her screams.
I’m done. Mars is looking increasingly attractive. Humanity, you suck.
That’s a fucking dog-tornado-alert-siren.
It also comes out of /pol/, and is called “hILLhISTORY”, a reference to “hh” — “Heil Hitler”. And Donald Trump tweeted this bit of poison himself. Isn’t it reassuring to know that the Trump campaign is getting their slogans and ads crafted for free by the most evil collection of assholes on the Internet?
Earlier in this ugly election cycle, I read many articles arguing that, while they were not defending him, Trump was not literally a fascist. Don’t do that anymore. While you might have some clause you can pull out of your textbook definition to say that he doesn’t meet all of the specifications, he meets all the essential qualifications. He’s practicing the demagoguery of hate.
We’ve also allowed the demographic of ignorance to grow out of control to give him a power base.
Now Corey Lewandowski is claiming it was a simple “sherriff’s star”. These people are dishonest and disingenuous through and through.
By the way, fuck CNN for hiring that Trumpian bozo as a correspondent. This is also how the corruption of fascist demagoguery spreads–the assholes always fail upwards.
I get this question all the time, and I just got asked it again: “Did you really say that humans are fish in that Ray Comfort video?” Yes, I did, and I guess I have to explain it again.
There are multiple meanings of “fish”. We can use it to refer to specific species or an extant category of animals: salmon are fish, halibut are fish, herring are fish. No one objects to that, and they all understand that if I said “humans are still salmon”, that would be wrong.
But another way the term is used is as a descriptor for a clade. A taxonomic clade is a “grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor”.
So, for instance, humans belong to the mammalian clade, which includes mice and cats and cows. If we have transhuman, part-cyborg descendants, they will still be mammals, because, note, by definition a clade must include all the descendants of an ancestor. We’re trapped! There’s no way our progeny can exit the clade!
We’re also members of multiple clades. For example, the tetrapod clade is the group that descended from a 4-limbed ancestor, an early amphibian, so it includes frogs and salamanders, and also reptiles, mammals, and birds, and the fact that we’re weird bipeds that have specialized our two pairs of limbs in odd ways, or that birds have turned a forelimb into a wing, doesn’t get us out of the club labeled “four footed”.
The thing about the clades of mammals and tetrapods, though, is that we have convenient generic labels for the groups: we can say “humans are mammals”, and we don’t get hordes of clueless people gawping and saying, “Did he just call me a mouse? That’s absurd!” But we belong to another clade, all the organisms descended from an ancient fish, and “fish” is the common label there. People generally have such a dim comprehension of the diversity of the fishes, though, that they hear a biologist pointing out that we belong, and will always belong, to the fish clade, and they think, “Did he just call me a sturgeon? That’s absurd!”
One way to get around the problem is to get technical. I could say we’re all gnathostomes, and nobody would freak out because most of them wouldn’t have the slightest idea what I was talking about. So I could hide in technical obfuscation. But the point is that you are descended from an ancestor that was a torpedo-shaped aquatic vertebrate with gills, a fish. You can never escape your ancestry. Embrace Your Inner Fish.
By the way, another way “fish” is defined taxonomically is as a craniate that is not a tetrapod, and if you use that definition, we are not fish. But that requires explicitly creating a paraphyletic group (that’s what you call it when you take a clade and willfully exclude a smaller clade), and that’s just annoying.
