Let’s just call this my random act of mischief for the day! 😉
Michael Skinner, professor of biological science at Washington State University just came out with the following in the popular press:
Unified theory of evolution Darwin’s theory that natural selection drives evolution is incomplete without input from evolution’s anti-hero: Lamarck
Is it indeed time to revise the theory of evolution? Or… Is Skinner in error and invoking a common misconceived textbook caricature of Lamarck? IMHO: Short answers = NO! & YES!
I urge any and all to read Mark Ptashne’s insights before weighing in the discussion.
Bottom Line: Nucleosome modifications may be necessary for epigenetic responses, but they are not sufficient.
To quote PZ Myers, who cuts to the chase:
We say epigenetics is really important in development and in physiological adaptation — it’s good to know more about it, and is essential for understanding the state of the organism. But evolution? Meh. Acquiring the process of semi-permanently modifying the cell state is something that was a key innovation (OK, many innovations) in EVOLUTION [emphasis mine], but it’s been overhyped as an information transfer process on evolutionary timescales…
So who got the epigenetics story right? PZ Myers & Mark Ptashne?… or Michael Skinner?…
I’m not a biologist. But I’ll go with PZ Myers and Mark Ptashne.
What’s wrong here, are assumptions about genetic determinism. As I see it, the DNA does not determine the organism. Rather the DNA determines some basic biological processes. And, in turn, those basic processes determine the organism.
The thing is, though, that those basic processes are themselves highly adaptive. So development is already adaptive. Post natal development is highly adaptive, and we have a system called “education” to make the best use of that post natal adaptation.
So, sure, there is intelligent design. The organism designs itself because of the adaptive biological processes.
The funny part is that the ID proponents are always railing against materialism and mechanism. But their own thinking is far more materialistic and mechanistic than is mine.
What seems obvious to me, is that the size of the DNA is far too small to constitute a complete specification of the organism. And therefore most of the “intelligent design” must take place during embryonic development and later.
As for Lamarck? Well, sure, organisms can acquire new traits (i.e. learn). That’s possible because of the adaptive nature of biological processes. Transmission to future generations seems to be mostly cultural, at least initially. Then the Baldwin effect can step in, and result in some supportive genetic changes arising over time.
From Skinner:
Whatever is he talking about? I can’t tell, because there are no citations, and I certainly don’t see any issue I’m well-aware of.
And how did he manage to mangle the definitions of genetic drift and epistasis?
Hi John
The format of the online article is somewhat unusual. Skinner does refer to citations. To find the citations he references, you need to click on the underlined words in any given paragraph.
For example, Skinner references this citation in the paragraph you quoted, by clicking on the word “explain”:
http://mbe.oxfordjournals.org/content/31/6/1568.abstract?ijkey=b3250419a5efc0935f94a5a0c4f7c253e7c5a209&keytype2=tf_ipsecsha
In the following paragraph, Skinner cites this reference:
http://www.genetics.org/content/genetics/172/1/197.full.pdf
That all said – even after a cursory perusal of those two citations, I have to agree with your assessment of Skinner’s précis as being egregiously incorrect.
Evolutionary theory will presumably always be incomplete anyway. That’s no reason to leave it any more incomplete than we can help, but there is no shortage of changes that have occurred in evolutionary theory, and no doubt more will occur.
Epigenetics at most is a rather minor issue in evolutionary theory, in my view. Of course it makes some difference to the degree that it actually exists, but there doesn’t seem to be any significant opposition to including any well-supported epigenetics in evolutionary theory. Skinner seems to be complaining about nothing, and bringing up Lamarck as a bit of hype.
Glen Davidson
I giggle in anticipation at Allan Miller’s predicted response. 😉
to cite PZ Myers again: this is all old news!
http://scienceblogs.com/pharyngula/2013/12/03/higher-order-thinking/
I’ll go with Ptashne, but add that multigenerational transmission of epigenetic modifications of DNA reverts after at most a few generations. So if a population of chimps changes by epigenetic means, the change will get lost unless later stabilized by a change in DNA sequence. So epigenetic mechanisms are not a means of long-term evolutionary change.
A further fact to note is that epigenetic effects of environmental changes are not preferentially in the direction of adapting to the environment — they are random effects such as giving you a higher rate of heart disease.
(Oh, and terminologically, they aren’t examples of Lamarck’s use-and-disuse mechanism either).
Hi Joe,
As always, I remain in your debt. You were the first to alert me to the possible importance of genetic assimilation in evolution.
I also agree with you that phenotype plasticity is not tantamount to what textbooks speciously label Lamarckism. Oh, and FTR – I remain most grateful to both you and walto for clearing up some misconceptions on my part; regarding what Lamarck really said and did not say.
best and grateful regards
Funny. Let me quote you:
Ah, I see. I agree with you that Skinner’s citations don’t in the least support his claims. They in fact seem completely irrelevant, having only a word or two in common.
Perhaps all evolutionary change is short-term.
John – it would seem to be that you and I are in total agreement on all counts!
What just happened!? 😉
In fact, I would be remiss if I failed to credit your (albeit sometimes impatient) indulgence in bringing me up to speed, on matters biological
gracias…
You seem to have missed the part about those processes being highly adaptive.
There needs more options for who is right. Evolutionists are always in a curve of error.
Different places in the curve but…
Its once again that evolutionism doesn’t make sense intuitively.
Selection pushing the glory forward seems unlikely.
So they grasp for other options other then the obvious.
The obvious being biological change is completely within existing equations/mechanisms in the present genes.
no selection or mutations or lucky breaks.
Lamark simply guessed there was this innate ability to change.
He knew they needed help.
The great example is human bodies.
The colours and other traits could onlky of come from sudden instant change within a poulation.
We never evolved our colours etc.Impossible.
So people are the great example of how biology changes. case in npoint. Case closed. There it is. Its real. But not from dumb ideas . its innate triggeres in existing Dna options.
Of course all the IDists who argued for “genetic entropy” will also buy this argument…
“the rate of random DNA sequence mutation turns out to be too slow to explain many of the changes observed”
So the mutation rate is both too fast and too slow…
They’re both supposed to undermine evolution, so why the hell not!
dazz, this has nothing to do with “genetic entropy.”
So the mutation rate has nothing to do with how deleterious mutations accumulate and how able natural selection is to weed them off? That’s news to me
Quick, quick, which position is best for clinging desperately to atheism?
Go with that one.
Are you saying epigenetic theory has theological implications?
R O F L
Makes no sense to me either. It reads like the only type of mutation he knows of is point mutations. Single nucleotide polymorphisms. It’s like he has got the impression, that evolutionary biologists think, that all evolutionary innovation and change must be due to the incremental accumulation of relatively few single nucleotide changes pr. generation. If that’s what he thinks, what he writes almost makes sense.
One comment moved to Guano. Please follow Lizzie’s simple rules about personal insults.
“Highly adaptive” as in “each next generation/species is better adapted than the previous one”? If the lower species are less adapted, then why are they still around? Because of their persistent system of education? What exactly are you referring to as “education” among anybody else than humans?
If post natal development is highly adaptive, can you educate a newly born monkey into a human being? Not that adaptive, I assume. So, how adaptive is it and why do you say it’s highly adaptive?
Are you saying that Lamarkism doesn’t?
Haha, what a fast mind you have. ROFL. Hahahaha.
(satisfied Patrick?)
Hey phoodoo, try to explain what the theological implications of epigenetics is.
Rumraket,
Right after you explain how random copying errors created a system of epigenetics that is fundamental for DNA to even work in the first place.
Let’s pretend I have no idea.
What follows?
Can you elaborate on this phoodoo? Why is epigenetics fundamental for DNA to even work? Work at doing what, specifically?
Well, you could stick to addressing ideas instead of coming up with ways to skirt the rules while still insulting people, but it’s your choice how you are perceived.
I will answer for you, it can’t. And since epigenetics can’t arrive through random copying errors, we need a much better explanation that Darwinian evolution for how life developed.
Welcome to your designer. I know its not what some of you were hoping for.
I was hoping for something more difficult. 🙂
No, no, no.
Adaptive to the current environment, but not transmitted to the next generation unless via the way that the children are raised.
Why can’t it?
If it can’t arrive through random copying errors, is it possible it can arrive through another natural mechanism? If not, why not?
Try to spell out the logic.
I suspect that rather than us supposedly not hoping for it, you are the one that does hope for it. But let’s put that aside for the moment.
So far, all you have done is assert. You have asserted what I’m asking you to explain. And by explain I mean with logical arguments, that start with premises and end in conclusions. They usually look like this:
P1: There is a molecule called DNA.
P2: DNA mutates.
P3… etc. etc.
Conclusion: Therefore the epigenetic mechanism cannot arrive through a natural process.
I suspect you will discover rather quickly, should you attempt to take up this challenge, that you will not be able to arrive at your desired conclusion.
Yeah but, you know, it’s phoodoo. What can we do? -.-
Can you elaborate on this phoodoo? Why is epigenetics fundamental for DNA to even work? Work at doing what, specifically?
Please don’t forget to answer this one too.
So now it’s adaptive, not highly adaptive?
Sigh!
Highly adaptive.
Adaptive does not necessarily imply heritable.
Okay, not heritable this time. But highly adaptive by what standard? Compared to what? I asked this:
If post natal development is highly adaptive, can you educate a newly born monkey into a human being? Not that adaptive, I assume. So, how adaptive is it and why do you say it’s highly adaptive?
I don’t know of a standard.
There’s more adaptivity during development than later.
No, it’s not that adaptive.
Unnamed natural processes for the unexplained is the evolutionists game. “Natural process of the gaps argument. ” That’s quite an assertion Rumraket.
The big bang, the constant laws of the universe, formation of DNA, formation of living cells, the existence of energy, the existence of molecules, consciousness…the list of things evolutionists want to hope for a “natural” explanation one day keeps growing. Now they need one for epigenes too.
Its a philosophically meaningless plea. The cause is…No cause whatsoever. Just is. That is the hope atheists cling to.
What about them? I don’t know how (or even if) the universe came to exist. Do you?
That one we know. Ribonucleotide-reductase. Look it up.
I presume you bring these up because you think you know the answer?
Yeah that one we also know. It’s electromagnetism, basically. Electrons and protons attract each other, forming atoms. Atoms in turn attract each other and make molecules.
Do you have an alternative scientific theory for the formation of molecules?
It seems to me everything we have so far explained had a natural explanation. Are you saying there is no detectable trend?
Take a look at the attached picture and imagine you come to a race between two horses. One horse has won the previous one million races, the other hast lost them. They’re about to race again, where do you put your money? Is it rational to bet on the horse that lost a million times? Is it irrational to bet on the horse that won a million times? Can that really be described as a “hope”?
DNA methylation is performed by enzymes. Are enzymes unevolvable? I’m just asking, you seem to think you know without any shred of doubt.
I’ll just file this under irrelevant commentary.
Are you going to back up your assertions at some point? Specifically, your claim that:
“a system of epigenetics that is fundamental for DNA to even work”.
Can you elaborate on this phoodoo? Why is epigenetics fundamental for DNA to even work? Work at doing what, specifically?
And:
“Right after you explain how random copying errors created a system of epigenetics that is fundamental for DNA to even work in the first place. I will answer for you, it can’t.“
Rumraket,
This is the shallowest understanding of the problem I can possibly imagine one having.
“Oh well, there is a natural explanation for molecules…electromagnetism. ” Man this must be way over your head.
Here is what I am pretty sure I do know: the universe exists. Electromagnetism exists. Gravity exists. Consciousness exists. Molecules exist. DNA exists. Cells exist. In order for all of these things to exist, there must be a set of rules and forces and coherence between these many different phenomenon. When people want to say, well, so, that’s natural, I want to grab them and shake them and say, “What does that mean!” It means nothing. That’s not an explanation for anything.
The whole point is that people are saying the universe is organized. Physics is organized. Living things are organized. NATURE is organized! This begs for an explanation. What organized it??
Its not only bad to just brush off why and how an entire universe can organize itself, it becomes even more ludicrous to just brush off as meaningless why and how a LIVING THING can organize itself.
Your ridiculous attempt for how DNA exists is that enzymes do it, shows just how far off the mark you are. Why are there even enzymes! And why does an enzyme make things that are intelligent!
“Well, it just does, who cares why. Its natural man…” Is that is your frame of thought, then of course NOTHING would be of wonder to you. If life is teleological and its goal is increased complexity and intelligence, if one has your vacuous philosophy, they can just say, “So, that’s just what nature does. No need for a cause. ”
If atoms self-organize themselves into living cells, you can escape the implications by saying, “So what, that’s what nature does.” If dust spontaneously swirls into a GPS led spacecraft, the simpleton can just shrug his shoulders and say, “Well, I guess that’s what nature does…accidents happen”
A couple thousands years ago a bunch of uneducated blue collar Greeks knew how stupid that kind of (lack of) thought was. It has slipped right past you however.
There’s nothing at all natural about most of the items on that list.
The Sun? Supernatural. The Earth? Supernatural.The Stars? I think those fall under suns. etc. etc. The entire material edifice is supernatural. 🙂
I don’t think you know what the word means then.
Okay, but the explanation for molecules is electromagnetism.
If you weren’t interested in how molecules form, why bring them up? Rather than point to a host of emergent phenomena (as you imply they are) such as cells, molecules and so on, you should have left them out entirely and just focused on the fundamental forces. Where do the laws and forces come from? That is your question.
It’s an entirely fair and interesting question, but I’m not claiming to know the answer. You want to caricature this by saying naturalism entails “it just exists”. But I’m not saying that, I’m saying I genuinely don’t know. I have no idea if there is a cause of some sort, or a reason/intention behind their existence, and if there is, I have no idea what that cause or reason is. Are things just existing or having certain properties “for no reason” absurd? Then how do you avoid the infinite regress of causes?
Traditionally theists will say God made them, and God doesn’t need an explanation because it is God’s nature to exist. He can’t not exist.
Which then raises the question, can’t the same be true for the laws and forces? It is in their nature to exist?
Can’t we immediately ask, then, WHY is it God’s (or the natural world’s) nature to exist? So he/it just happens to have this amazing property that he can’t not exist? That’s just His/it’s nature and there’s no reason for it?
This debate is very old and I’m not here because I claim to have solved it. But among the attempts at answers I have seen, there isn’t any of them that doesn’t end in either brute fact, or infinite regress. Sooner or later all positions terminate in something that itself is unexplained, or it goes on inifinitely and without end.
Take your pick. Or don’t, like me. You don’t actually have to choose. You can simply stop at “I don’t know and I don’t know how to find out”.
No, there is nothing about these entities existence that logically entails a set of rules governing all of them.
We have discovered what appears to be a consistency in the material world, we call them laws of nature(but if the word “nature” is an obstacle, you can call them “physical laws”) and we think they apply everywhere to all material objects(because they appear to). But from the perspective of logic alone, there’s nothing that says they must exist.
And that is a good question, with much debate around it so you won’t find a great consensus on it. I generally agree with the working definitions given by Jeff Lowder here: http://www.patheos.com/blogs/secularoutpost/2014/04/17/the-nature-of-naturalism/
Merely calling something by a name explains nothing, I agree completely.
The way I understand the terminology, naturalism is meant to be synonymous with some form of physicalism/materialism. So when I say it is “natural”, what I mean is it is material/physical. That it is amenable to investigation through the senses and the empirical sciences. That phenomena are due to physical and material forces of attraction and repulsion. That causal explanations are found in the interactions of material entities.
I don’t claim to know how these forces that act on material entities came to exist. I’m not even convinced they ever really came into existence in the first place. Again, I genuinely don’t know and nobody has been able to persuade me in any direction.
Yes, I agree. I don’t claim to know.
In fact, I don’t even see why we should think it more probable that it was organized by something external to itself, as opposed to it being a property of them that they can self-organize (in the same way we say matter has self-organizing properties). I don’t see a way to determine whether it is one or the other with respect to the entire physical/natural world, or to even put probabilities on it.
And if it was something external to it, was it organized by one or multiple other things? Did that or those things also require organization? I don’t know the answer to these questions.
Do you think you do? I’m not going to take your word for it and believe on your say-so, but I’d be interested in hearing a case for answers.
But who brushes it off? Is admitting that I don’t know really something that should be described as “brushing off”? I’d like to know, but to believe that I know requires evidence.
Who are these people that “brush off as meaningless why and how a LIVING THING can organize itself”?
What does it mean to “brush it off as meaningless”?
Why should we think there is a “why” to it, as in a meaning?
It seems to me even as there are things we as sentient beings, intend. Events we “mean to happen” when we take certain actions. There are also things we do not and yet they still happen. Things that don’t seem to have any meaning.
Suppose I throw a ball with the intend for you to catch it, but I’m terrible at throwing balls so it flies too high for you to catch, and lands in a puddle of mud, leaving an impression in the ground. What is the “meaning” of that impression?
I don’t think there is any. It was not something either of us intended to happen, it was an accident. A byproduct of something else. It could be a byproduct of something else and that something else was intended (after all, I did intend to throw the ball, so the ball flying through the air does have a causal explanation involving my intentions). But there is also an accidental part of the explanation for the impression. The unintended part of it.
Do all events terminate after a long chain in “intended” acts by a being, or are those themselves the byproducts of something else that came before it? What caused me to throw the ball too high? Is there a meaning behind that too? Is that something you would claim to know? What if that impression in the ground gets spotted by someone later, and this in turn inspires them to take certain actions? Are those actions now started by an accident? It seems to me they are at least partially.
I don’t know “why” (in the sense of meaning or purpose) living organisms can “organize itself”. I don’t even know if there is an answer to that question. Do you? How do you know?
But I do claim to know at least partially how they do it.
So it’s the infinite regression question. I’m being scolded for not claiming to know the nature of all causes and whether they truly terminate in a brute fact, or whether they go on forever?
No. If there is a “why” to it, I’d like to know it too. But I don’t just take anyone’s word for it.
There have been periods in my life when I felt there was no reason for “any of it”, I still wondered about it, and plenty of things was of wonder to me. They still are.
You seem to know very little about how I think, yet speak as if you’re certain you do. Or as if these are questions that have not crossed my mind.
I agree that would be a vacuous statement. As would brainlessly declaring that “god made it so”. Neither statement has any explanatory power, they seem to say nothing that sheds light how or why.
What implications? Please spell out the implications with valid deductive logic.
If atoms self-organize into living cells, then… what?
Yes, again, a vacuous statement. Equally vacuous to “well, I guess that’s what God does, miracles happen”.
I would take this criticism seriously if you could point out a single instance of me ever saying “well, i guess that’s just what nature does” or something equivalent. Go digging.
When did I imply they are emergent? I don’t even believe in that empty concept, so why would I imply it.
You just tried to duck the core tenet of my post. If these things “self-assemble” you need a better explanation (if you actually want to say something to people who think) than, well it just happens, nature, nature…
So we not only have the problem of the forces coming into existence, we have the problem of things self-assembling and creating more complex things, we NOW have the problem of DNA self-forming, epigenes self-forming, cells self-forming. How many “nature of the gaps” can you try to explain?
If the theory of evolution involves, well, nature just does it. Things just make themselves. Well, you should probably be a bit more clear that this is what your theory is, so we can have a better discussion about its place in school classrooms.
Because you have all these high school kids, and school boards thinking you are saying Darwin’s idea that random mutations along with natural selection is what life is all about, but you forgot to say “Well, of course that’s not ALL there is! There is also the nature just does it part! But its MOSTLY just Darwin. The nature just does it part? Eh, let’s not emphasize that for now. They’ll learn that part online somewhere. We will just keep it on the downlow, shall we?”
Go back and read your whole post. The nature just does it part is implied throughout, certainly much more than I ever implied I believe in emergence as a meaning for anything.
If instead of nature just does it, you prefer “electromegnetism just does it, and enzymes just do it, and DNA just does it, and cells just do it” ok. Or if you prefer, “well we used to think about the causes, but now let’s ignore that for now” you can say that too.
But either way it seems we should inform the school boards, because that is nothing like random mutations and natural selection (along with a few other things that we don’t really talk about) does it.
Approximately here: “Here is what I am pretty sure I do know: the universe exists. Electromagnetism exists. Gravity exists. Consciousness exists. Molecules exist. DNA exists. Cells exist. In order for all of these things to exist, there must be a set of rules and forces and coherence between these many different phenomenon. When people want to say, well, so, that’s natural, I want to grab them and shake them and say, “What does that mean!” It means nothing. That’s not an explanation for anything.
The whole point is that people are saying the universe is organized. Physics is organized. Living things are organized. NATURE is organized! This begs for an explanation. What organized it??
Its not only bad to just brush off why and how an entire universe can organize itself, it becomes even more ludicrous to just brush off as meaningless why and how a LIVING THING can organize itself.”
And here: “If atoms self-organize themselves into living cells…”
This whole thing above is one long question about where the “laws” that make things “self-organize” come from. Self-organization is a type of emergence. When things assemble, they give rise to new things, such as living cells. That’s emergence right there. When water molecules assemble into snowflakes and ice, that’s emergence.
It’s not my fault you don’t even know what emergence is. You are probably referring to the metaphysical concept of emergentism which stands in contrast to reductionism.
I agree, which is why I have never said “it just happens”.
That’s what the physical forces acting on the constituents under the local conditions at the time, explain. The physical forces describe and predict the interactions. The physical forces are the explanations for how atoms and molecules form, for example.
Again, I don’t know why the physical forces exist, or why they are the way they are. I don’t even know if there is a ‘why?'(as in a purpose or meaning to it). Do you? How did you find out?
I’m not really into this whole gap-reasoning thing. Instead of just mindlessly placing labels on events I do not know how transpired, I simply admit my ignorance.
For example, I don’t know how life originated. I do know there is evidence it was through a physical and chemical process. You know, a “natural” process. But calling it that is not supposed to constitute an explanation, it is a means of categorization. It is another way of saying that the evidence points to the workings of the physical forces and laws, as opposed to… well, violations of them through divine intervention.
Okay, noted. Let me be very clear: I’m aware of no theory of evolution that involves “nature just does it, things just make themselves”. In fact, I believe no scientist has ever proposed such a theory of evolution.
No, I don’t think that’s what is being taught anywhere. I think you made that up. The particular statement you made there is a caricature you use to substitute for what is actually being taught.
Again, please point that part out. Explicitly. Don’t just quote my entire post and say something weaksauce like “it’s all over your post”. Because it isn’t.
By the way, I notice you have still not even attempted to rise to defending your claims about the epigenetic mechanism being required for DNA to work, or that it can’t evolve. Am I to take these long-winded diversions as your concession speeches? If so I accept. In the future, I expect you to never again say “epigenetics is required for DNA to even work”, or that epigenetics can’t evolve, since you so obviously now believe you cannot defend such a claim. And you wouldn’t be claiming things you can’t defend of course, that’s just not the kind of person you are.
Oh it is? Then why did I write so many times that I simply don’t know why nature does what it does? And why did I write that I’d actually like to know?
Does that not stand in contradiction to your claim that I think or even imply nature “just does it”?
And while we are on the subject, do you know why things happen phoodoo?
Electromagnetism is one of the physical forces. It is a force of attraction and repulsion. Why electromagnetism exists, and why it works the way it does, I do not know. I’d like to know if there even is a why to it. Do you know and if so, how did you find out?
We know how enzymes and DNA works phoodoo. That’d be those damned physical forces again.
Why are all atoms, whether they make up molecules or not, all subject to the same physical forces and laws? I don’t know. Do you?
All of that is still there. The diversity of life is due to evolution by random mutation, natural selection and genetic drift. A bit about population mechanics, migrations, geographic isolation and so on.
The fact that at another level these things have a description in the workings of physical forces acting on subatomic particles and fields, and we do not know why these forces exist or why they are they are, does not invalidate the explanation from the theory of evolution at the level of DNA, mutations and population mechanics.
That’d be like saying a story that involves a car going from Los Angeles to Las Vegas is invalid because it does not contain a statement about why gravity exists and keeps the car on the road.
And so on?
Epigenetics for one has nothing to do with random mutations and natural selection, and it is epigenetics that determine which genes will be turned on and off. Thus they are at least as responsible for the diversity of life as any so called random mutations and genetic drift. Furthermore natural selection is not capable of adding diversity, it is only capable of removing it.
So if your answer is not simply that nature does what it does, but that you don’t know why nature does what it does, then this might be a heck of a better place to begin teaching students about biology, instead of the bullshit Darwin is life propaganda.
No not exactly. That would normally just be what is collectively called gene-regulation.
Take a loot at the Lac-Operon, which is a classic example of gene regulation taught in molecular biology. Gene-expression is environmentally regulated (that means regulated by something in the environment). In the Lac-Operon, the genes for lactose metabolism are controlled (turned on or off) by the environmental concentrations of lactose and glucose. If there is both glucose and lactose present, the cell will normally not be turning on the gene that codes for the enzyme that breaks down lactose into galactose and glucose, because glucose is a superior energy source alone. When the concentration of glucose drops below a certain level, it fails to inhibit expression of the beta-galactosidase enzyme, which in turn gets expressed and starts degrading lactose (which in turn releases glucose, which can lead to inactivation again).
The wiki articles on this (gene-regulation and the Lac-Operon specifically) are actually quite good, go look at them. That’s classic gene-expression and regulation.
Epigenetics is a mechanism by which gene-expression patterns are heritable over multiple generations (potentially permanently, though this has yet to be demonstrated actually happening). To pick the Lac-Operon as an example, epigenetics would seek to explain how when an E coli cell divies, the daughter cell inherits a Lac-Operon in some particular state of regulation (for example, with beta-galactosidase expression being active).
Some theorists are proposing that the epigenetic mechanism could theoretically result in actual DNA mutations, if by some mechanism methylations of bases server as markers for site-directed mutagenesis. That’s when an inherited expression pattern could become permanent.
It is known that expression patterns are heritable, but so far they’re only known to last a few generations. For example in the Lac-Operon, when an E coli cell divides and there is lactose, but no glucose, in the cytoplasm, the daughter cell will inherit roughly half of that lactose, in turn keeping lactose-metabolism turned on. If it divides again, again the lactose concentration is cut in half. All the while lactose is being used as a substrate by the enzymes of the cell, eventually it runs out, glucose has accumulated and lactose-metabolism turns off again. So while the expression pattern was heritable, it only lasted a few cell divisions before the signal ran out.
The questions is if there are permanent methods of expression. Are methylations heritable over multiple generations? It’s an area of ongoing investigation.
Gene-expression is reponsible for multicellular development and the cell-cycle, yes. But what’s responsible for the origin of regulation sites in DNA, and the genes to be regulated, in the first place? Mutations, natural selection and genetic drift.
Which is why geographic/reproductive isolation of subpopulations, genetic recombination, drift and mutations, are thought to be the diversity-producing mechanisms.
This makes no sense. Nobody teaching biological evolution is saying they know why the natural world has the properties that it has. And it isn’t necessary to know that, to teach how evolution happens.
I don’t know what this “Darwin is life propaganda” is even supposed to be. Never heard of it.
Before anyone revises the theory of evolution I would think someone needs to come up with a theory of evolution. There isn’t one yet.
You cannot revise a theory of evolution if it doesn’t exist- can someone please link to it? I am not asking for a link to someone talking about it as if it exists. We would like to see the actual theory so we can read what it really says.