- A recent study identifies phenotypic plasticity as the ability of tadpoles to change how they look and act, and how their tissues function, in response to their environment. If the pond also contains fairy shrimp, some tadpoles turn into aggressive carnivores and sometimes, the carnivorous tadpole stage becomes entrenched – without the need for a dietary trigger. This plasticity has also been confirmed in lizards, roundworms, and yeast. When yeast is exposed to the herbicide paraquat, the yeast copes by eliminating some or all of the DNA in their mitochondria, the cells’energy-producing organelles.
- Some consider this a classic example of “plasticity-first evolution”. On the surface, the findings vindicate Lamarck. The plasticity those changeable tadpoles display is built into their genetic code. And when an “acquired” trait does become “permanent”, it is because of mutations that “fixed” the plastic trait – a process biologists call genetic assimilation.
- Since plasticity is a built-in trait of so many organisms, it has obviously been mistaken for “evolution”. “Permanent” claim is meaningless given all organisms populations are ever-changing. The main questions are “what are the limits of plasticity?” and “what happens over the very long time?” The evidence to date is very clear:
a. Plasticity is a built-in widespread if not universal characteristic of organisms
b. It is limited in scope to a few traits like color, behavior, and metabolism
c. Plasticity is reversible rather than cumulative
d. It is not divergent as toads, lizards, roundworms, yeast, etc. never turn into not-toads, not-lizards, and so on. - This is a repackaging of the same stories sold as proof of “evolution”. Darwin’s finches, the peppered moth, antibiotic resistant bacteria and, why not, the tanning humans. Too bad all these not only do not diverge into new organisms, but they all have been shown to revert eventually when the stimulus is removed. Finches change back their beaks depending on environment and never turn into non-finches, the black moths reversed to white and never to not-moths, antibiotic resistance disappears from the population when we reduce the use of antibiotics (see NIH recommendation), and neither light-skinned Nordics, nor dark-skinned Mediterraneans turn into not-humans under any circumstance.
https://www.nih.gov/news-events/nih-research-matters/reducing-antibiotic-prescriptions
Do I sense some bitterness? You are doing your own research, but did you seek the mountain top guru? She’ll cure you of bitterness (and other things perhaps) 🙂
This is false. Read about ‘regression to the mean’.
Reversion then. Variation ‘reverts’ to the mean. Still nonsense.
Repeat: Differences due to phenotypic plasticity do not persist in a common environment, so cannot be responsible for species differences (as you suggested) nor for phenotypic variation with a proven genetic basis (such as industrial melanism in peppered moths).
Do Asians, Native Americans and Africans turn pale-skinned when they move to Europe? No, they don’t, because the difference in skin colour is genetic. In the absence of evolutionary mechanisms genetic variation persists
I was warning you that some people might read your comment as saying that modern Africans are primitive. Suit yourself, though.
Did you read how Allan and T_aquaticus defined evolution? How can a genetic/heritable change NOT have anything to do with Mendel?
Nonlin.org,
To make this discussion somewhat more productive, would you mind answering a couple of questions? You have been talking about Mendelian inheritance and reversion (regression?) to the mean, and I wondered how you squared those concepts with your ideas.
1) Mendel set up his experiments using stocks of pea plants that were true breeding for certain distinct traits (like wrinkled peas). How was he able to prevent these plants from “reverting to the mean”?
2) You keep on saying that there is a reversion to the mean. The interesting thing is, if there is differential survival among the offspring related to a trait (say skin color), then you will have a NEW mean. Will the population revert to the new or the old mean? If the latter, what preserves this memory of the old mean?
That’s not at all clear. It’s like a bad translation from who knows what language.
Are you serious? Are you saying that white Europeans are not descendants of black Africans? Maybe it takes more generations, but are we humans of all different colors and nuances not all members of the same family? Why make childish claims? What “evolutionary mechanisms”? It’s mere plasticity as sciencemag shows. Look at the examples given including lizards changing color.
Now everyone defines as they please? You got it exactly backwards: not Mendel but Darwin has nothing to do with “genetic/heritable change”. Look at Mendel’s laws / Punnett squares / Hardy-Weinberg equilibrium – there’s no room for Darwin’s nonsense.
So you don’t understand anything you read? That’s embarrassing. For me too for carrying on with you.
This is where you go wrong big time: mean is not uniformity. The variability never dies as we see in the distinct traits (including wrinkled peas). But they’re all peas and we’re all humans. And unlike the Eugenists, we can’t say that the white man has evolved more than the African. And that’s exactly what this story of plasticity shows you: variability comes, persists and may or may not go, yet these variants do not represent “evolution”.
If there were “differential survival” as in Darwin’s claim, we would not have all these variants, coexisting, right? The mean is more inclusive than superficial features like skin color, height, weight, etc. Think of humans – we’re all different, yet none of these traits make us less humans.
And now try to mentally “evolve” an organism: a peacock with a bigger tail or a larger lion. Will they do well or will they have a harder time just like the peacock with a smaller tail and the smaller than normal lion? And if they manage to reproduce, would their progeny go even more extreme or would they be more like your average peacock or lion? You’re in luck because there is experimental evidence as to what happens.
Nonlin,
You are not making any sense at all, I am sorry to say.
You appear to be claiming that the differences in skin color between races are NOT genetic. I am embarrassed for you.
You completely missed Corneel’s point re “true breeding” strains: when geneticists such as Mendel use that phrase, what do they mean by it, and why is it key to our conversation? Try to explain.
What isn’t clear about it? I am happy to explain.
Yes, let’s look at the lizards, shall we?
So not mere plasiticity but also a genetic difference, agree? How did she find out? She observed persisting differences in a transplant experiment. See?
Hang on. My irony meter just exploded.
Let’s consult the good ol’ wikipedia oracle about this:
[emphasis mine]
Genetic drift, migration, mutation and selection are the four known evolutionary mechanisms. You are wrong.
Thanks. This comment interests me. I am wondering how individuals in a population continuously revert to the mean whereas the variability never dies.
Will you please explain this? I would like to hear more about this “mean”, because I do not understand what it is. Is it like an archetype or a blueprint? What does the “mean” pea plant look like? What does the “mean” human look like?
You seem to be happy to accept variation in a species, but in your peacock/ lion example you argue that when some individuals move too far out they are pulled back to resemble the “average” peacock or the “average” lion. What are those boundaries? What is that average? Why do they exist?
ETA: I am also curious about the “experimental evidence”, as it may help us find out what you are talking about. Can you present it?
That’s not my claim. You misread.
Looked back and didn’t find the quote you mention. Care to go over that point again?
1. Start with: What “differences”? What “common environment”? Better yet, rephrase the whole thing.
2. Plasticity is not distinct from “genetic difference” – I already provided that quote from the article. To your quote: so what? Of course there’s “a genetic difference in the lizards’ ability to change color”. Same as in humans. Had they observed the lizzards long enough (many generations), they would have seen regression to the mean.
3. ?
4. Would we be having this argument if there was ONE confirmed “known evolutionary mechanism”? NO. So not “known”, but “fantasized”. Also, that particular research excludes “evolution” and that was the point, remember?
1. I am not reinventing the wheel here. Are you disputing ‘regression to the mean’ in biology? Ever heard of the normal distribution for whatever biological measure? Pea plant is farmed (to extremes), so not a good example. But there are all kind of stats for the average human. Is this news to you?!? Here’s a quick find study for you: https://www.sciencemag.org/news/2015/03/how-big-average-penis
2. No hard boundaries. It’s like a spring – the more you stretch, the harder the pull back (or it just snaps). You can see that in domesticated plants and animals. Mutts are resilient while pure breeds have all kind of problems. Again: is any of this news to you? You seem to agree with my two examples. Then why the push back?
3. It’s all around you. Have you ever heard that “2 tall parents will have shorter children”? Apparently Galton studied that first in 1886.
General comment: I notice the typical Darwinist reply to my:
“the sky is blue” argument IS EITHER “are you really telling me the sky is blue? …prove it” OR “how can you claim the sky is brown? …you’re so wrong”. And let’s not forget the BEST: “Ha, ha, you said the sky is blue!”
Here..
You are incoherent, and you keep repeatedly asserting things that are obviously wrong. I encourage you to take a course in biology.
It is clear from nonlin’s most recent post that he IS talking about good old-fashioned statistical reversion to the mean.
And he is correct that Darwin thought this was a problem, because he was unaware of Mendel’s work. Mendel’s observations on the particulate nature of inheritance solved Darwin’s apparent problem with regression.
High School Biology. Yawn.
In repsonse to
You wrote this:
To me, that appears to be you claiming that the differences in skin color between races are NOT genetic, but rather “mere plasticity”.
Please explain very carefully what you actually meant.
I already replied to Corneel’s: “You have been talking about Mendelian inheritance and reversion (regression?) to the mean, and I wondered how you squared those concepts with your ideas.”
with
“This is where you go wrong big time: mean is not uniformity. The variability never dies as we see in the distinct traits (including wrinkled peas). ”
No, Mendel didn’t solve none of Darwin’s problems. Instead, he killed “gradualism” and showed inheritance stasis – see Hardy–Weinberg equilibrium.
And of course, ‘statistical reversion to the mean’ as you prefer to call it is alive and well (at least you’re not disputing), and not something Mendel researched.
With “differences” I mean phenotypic variation. For a continuous trait like height this can be expressed by the variance, a statistical measure of variation. Some of the phenotypic variance is caused by genetic differences (e.g. one of the traits investigated by Mendel was dwarf growth) and some of it by environmental factors (say, the amount of light a plant receives).
A “common environment” is a location (like a garden or a lab) where variation in environmental influences (light, diet, etc) are minimized. Hence the phenotypic variation that persists between inbred / clonal stocks must be due to genetic factors. This is the insight we owe to Wilhelm Johannsen who made the phenotype-genotype distinction in the beginning of the previous century (yes, you are THAT far behind).
Analogies are tricky business for this audience but here goes:
What if I pull the spring on one side only? Won’t it just slide along? What tethers the metaphorical spring it to its place? I say nothing.
Yes, sir Francis Galton, thought so. Let me inform you that some stuff has happended since. It was Galton’s student, Karl Pearson, who saw that this would not be an impediment to evolution. As I argued before, once the population mean changes, the values of the NEW offspring will regress to the NEW mean. The mean is not a solid mooring point, but merely a description of the population’s central tendency at this point in time.
Galtons “regression to mediocrity” wielded as an argument against evolutionary theory in 2019. Gotta love this place.
Corneel,
Wikipedia on blending inheritance
I aspire to regress to mediocrity.
1. I don’t see your point. You’re not explaining “phenotypic plasticity”. Are you saying plasticity is not genetic? That’s wrong per sciencemag. You need to work on clarity.
2. & 3. I know you say that, but do you have any proof? Have you forgotten the “living fossils”? To your unproven generality, all I need is a counterexample, and here it is: Coelacanth. Something tethers this guy. But really, wherever you look you ONLY see “living fossils”. And let’s not forget the dead ones like the trilobites. Karl Pearson’s words weigh no more than yours.
If you don’t see any experimental evidence of “slide along”, then there is none. And the best chance you had was in the LTEE eColi. Yet there’s no “slide along” there. Therefore nowhere.
Oh, please talk to me! Like, I’d just die!
Nonlin.org,
Hang on, you pick me up when I say ‘regression’- a forgivable mistake when you use a familiar-sounding phrase in ‘reversion to the mean’ – yet here you yourself say ‘regression’. Is it any wonder I get confused?
Variance and variation. 2 more concepts I’ve just noticed Nonlin mangling.
Your question is ambiguous. Phenotypic variation caused by phenotypic plasticity is not genetic. Yet the shape of the plastic response itself (the reaction norm) can be genetically determined, as it is clearly is in the case of the spadefoot toads, and it can evolve “per sciencemag”.
Which Coelacanth? Are you talking about a species of Latimeria? I dare you to show me a single modern species that has been unaltered since the Devonian. I accept Cambrian rabbits as well.
You are just cherry-picking and turning a blind eye to the thousands of modern species that did not exist in their present forms in the distant past. Also, I note that you make no attempt to explain what this “something” might be that tethers species to their current form.
Look again. I didn’t use the word ‘variance’ here. Corneel did.
That was never the issue.
1. It’s still not clear what you mean. AGAIN you’re not explaining “phenotypic plasticity”. And my original question was very, very simple: “where does ‘plasticity’ end and “evolution” begin?” Yet you keep dancing around and never answering.
2. We agreed there’s variability around a mean, right? Then “altered” has no meaning in this context. See https://en.wikipedia.org/wiki/Coelacanth: “Its discovery 66 million years after it was believed to have become extinct makes the coelacanth the best-known example of a Lazarus taxon, an evolutionary line that seems to have disappeared from the fossil record only to reappear much later.”
3. It’s not that “did not exist in their present forms”, it is that “did not exist PERIOD”. You can’t seriously put together [say] A Afarensis and H Sapiens and tell me they’re the same, only “changed”. Yes, your task is impossible, that’s why you need to forget the fossils (that can only work against you) and only rely on experimental evidence like LTEE (that unfortunately for you, failed).
This high standard applies to my claim too: “All those organisms cited (and more) regress to the mean either as individuals or over generations” … “It’s called inductive reasoning. Of course it’s subject to falsification with one single counterexample. But you don’t have any, do you? ”
I pass. You fail.
I do not “attempt to explain what this “something” might be that tethers species to their current form” because we need to establish the facts first: what are we actually observing? Regression or Divergence? When we agree on that, then we can look for explanations.
Repeat Repeat Repeat Repeat: Differences due to phenotypic plasticity do not persist in a common environment, genetic differences do. It’s not that hard, is it?
Heehee, then “altered” ceases to have meaning at all. Devonian Coelacanths evolved into Latimeria species? There’s variability around the mean. Pakicetus evolved into modern whales and dolphins? Yes, but there’s variability around the mean. A lipid membrane enclosing some biomolecules in the Hadean evolved into Homo sapiens? Oh well, there’s variability around the mean.
Modern species of Coelacanth can be distinguished from fossil species, hence they have moved outside of the morphological variation that was present in the Devonian. They have not been pulled back into their primitive morphology by the action of invisible springs.
Australopithecus afarensis has remained unaltered through millions of years? That’s AWESOME! Eh.. where are they? Where is Homo erectus for that matter? Where is Opabinia? Where are the herds of Diplodocus grazing? I want to see them all, unaltered.
Alas, they have gone, and have been replaced. Where do the new species come from, I wonder?
No, you should not close your eyes to the weaknesses of your position. A tremendous amount of fossil, biogeographical, genetic, ecological and mathematical data is on the table already. Accept that you lack a satisfactory explanation for your proposed “reversion to the mean”, whereas evolutionary theory makes all the pieces of the jigsaw fit together.
You are still confusing the concepts.
What was then?
Allan Miller: You specifically stated that variation regresses to the mean.
Nonlin: This is false. Read about ‘regression to the mean’.
Me: Reversion then. Variation ‘reverts’ to the mean.
Nonlin: So you don’t understand anything you read […] embarrassing […]
I read you saying both ‘regression’ and ‘reversion’. So no, I’m not sure I understand your pissiness in that exchange.
Coelacanths – another fine example of misplaced application of the principle of induction. Because some species exhibit apparent morphological stasis, all species are static when compared to their fossil record. I wonder why people feel Coelacanths worthy of mention, then, if that were true.
Isn’t it beautiful? If modern and fossil specimens are similar enough then it is the same thing and that proves that species don’t change. But if they are not similar enough (like Australopithecus afarensis and Homo sapiens apparently), then we can’t seriously put them together, and species still don’t change.
1. If “repeat” fails repeatedly, you should try something else – like answering the questions asked.
2. Of course ““altered” ceases to have meaning at all” – that’s exactly what I explained. And then you start to make up stuff…
3. Meh. Not much different than Darwin’s finches from one another, some examples of dimorphism, canine diversity, etc. And this much in 70++ mil yrs: https://ecologicablog.wordpress.com/2013/08/24/coelacanths-are-not-living-fossils/ ? Pretty damning evidence against “evolution”. That’s why plasticity kills your “evolution” myth (if it wasn’t dead and stinky before).
4. Read again and stop making up stuff.
5. No relationship. You cannot tie H Sapiens to A Aferensis, etc other that with mythology. Again, you really must look for EXPERIMENTAL EVIDENCE (of course, if not afraid to jeopardize your religion).
6. Again, are you denying regression to the mean? Then you’re willfully blind and there’s no point discussing if you deny the OBSERVABLE. Look above – even DNA_Jock knows regression to the mean is THE LAW.
6b. I have been demonstrating here for a long time that “evolution” is illogical and contrary to the EXPERIMENTAL EVIDENCE. Again, would this forum have ANY purpose if there was a shred of EXPERIMENTAL EVIDENCE supporting “evolution”?
How could you possibly know I am confusing a concept I have not even discussed?
The variation does not regress to the mean – it is conserved. Also see the Mendelian conservation of alleles. If we have x% >7ft in the population, that x% pretty much stays the same over time (all things equal). Just that the descendants of the 7ft high individual are unlikely to further diverge to >8ft. It’s common knowledge.
Sorry about your frustration. I specifically warned you:
“Yes, your task is impossible, that’s why you need to forget the fossils (that can only work against you) and only rely on experimental evidence like LTEE (that unfortunately for you, failed).”
How about that EXPERIMENTAL EVIDENCE? None? Then how do you support your claim? By making up stuff?
See that’s the difference: there IS plenty of experimental evidence for ‘regression to the mean’. None for “divergence of character”.
I see a definition for “phenotypic plasticity” that is due to environment and not genetic – although they do talk about Alpha-Amylase 2B in dogs, so go figure. Anyway, what has that limited case to do with the inheritable plasticity described in the source of this OP?
When you say: “moved outside of the morphological variation that was present in the Devonian”, that doesn’t mean much. Most likely the environment has changed and yes, plasticity would then change the morphology. That’s not “evolution” aka metamorphosis aka transmutation of species. Exactly what this OP is all about – misinterpreting ‘plasticity’ as “evolution”.
Not denying it, and I am familiar with the study in question.
Very well, I’ll play along. Please present the data (you can take it from the original publication, or find some adapted figure somewhere online) and show how it prevents evolution from occurring by ensuring a reversion to the initial mean of mid-parent values.
The “all things equal” part is the problem here. Selection violates that assumption in your example.
That at least is a testable hypothesis: if your hypothesis is correct, one should be able to retrieve all the morphologies in the fossil record by adjusting rearing conditions of the modern morph. A bit hard for this particular group, since Coelacanths aren’t being cultured, but you consider this to be a general phenomenon, right?
So can you name an example of a modern species where development of some hidden fossil morphology can be induced by changing rearing conditions? That would support your position with the EXPERIMENTAL EVIDENCE that you seem to be so fond of. I can think of none.
That’s the book. The 1886 paper is here
Because when you say ‘variation’ you appear to mean ‘variance’. As illustrated by your very next words:
Suppose, as a thought experiment, all individuals with an adult height below 7ft were mysteriously killed. Let’s further suppose height is 100% heritable. What ‘mean’ are future populations going to revert to? How will they get there, from a situation where the frequency of lower heights is zero, and the current mean at least 7ft?
Nonlin.org,
How has the LTEE ‘failed’? Lenski’s bugs have changed. They show no sign of changing back. In fact, given the nature of the changes – the variation! – that has occurred, it’s hard to see how they could go twanging back to their original state (which Lenski has thoughtfully frozen).
You can’t be seriously asking for my counterfactual to your unsupported claim. That burden is entirely on you.
1. What “selection”? That has been thoroughly debunked: http://nonlin.org/natural-selection/
2. Sure, as soon as you find out and PROVE the “rearing conditions”. I am looking at more immediate evidence of regression (already cited): Darwin’s finches, the peppered moth, antibiotic resistant bacteria and the domesticated plants & animals.
3. Way to go asking others the same exact question you were asked first: to provide EXPERIMENTAL EVIDENCE. Will that hide the fact that you have no evidence? Not this time. Typical Darwinist attitude 🙂
1. “Appear”? Give it up and be done.
2. You’re supposing too much. More realistic is to think what happens with an engineered population when released in the wild. Maybe look at feral animals or antibiotic resistant bacteria… Does it spread, regress, or disappear?
They have changed like any other engineered organism including your very unnatural chicken meat. That’s plasticity forced upon them by Lenski & co. Now, let them loose in the environment (see previous comment) and let me know what happens.
Those bacteria mutated. Their DNA sequence changed. It is not a case of phenotypic plasticity.
Read again the source article for this OP. Who told you plasticity stops at DNA changes? I didn’t say “phenotypic plasticity” which seems to be a made up subset of plasticity.
Who told you that plasticity extends past DNA changes? You seem to be making stuff up. Mutation and plasticity are two different things.
Naaaaaaaaah! Nonlin? Making stuff up? Naaaaaaaaah!