Yeah, only in Dawkins’ dreams.
Look at the right atrium in these four creatures from Encyclopedia Britannica:
How did that right atrium evolve from one side to the other along with changes in its connection to the pulmonary artery? In the crocodile and snake the right atrium is on the right ventricle but in the lizard and turtle they are on the left ventricle.
Look at the aortas. In the lizard they are all on left ventricle, in the snake on the right ventricle, and then split for the turtles and crocodiles. How did those aortas migrate from on ventricle to the other without the transitionals being lethal?
Study the picture more and you’ll see, the Intelligent Designer seems almost to have a sense of humor in exploring the various implementations.
Darwinists will say, “we have sequence comparisons that demonstrate the similarity, therefore the transitionals had to exist”, but someone with an engineering mind would say, “so what did the transitionals look like without killing the organism?”
Is neutral evolution in play? No, because lethal changes aren’t neutral. Did natural selection cause the change? No, because natural selection would prevent the change. How about blind luck mutation. That’s possible if there are multiverses.
Wd40 accuses me of not naming one transitional that can’t exist in principle. Well above you have 4 transitionals that don’t exist in principle. Connecting these hearts via Darwinian evolution doesn’t exist even in principle. What were the functional transitionals as the atrium migrated from on ventricle to the other, or the aortas migrating from one ventricle to the other?
On could say, “Sal you have it all wrong, they all evolved from the 2-chambered heart”. 😯 Well that only makes the problem worse, not better! The above hearts are not 2-chambered. See below to understand the difficulty. But first, I note, I’m not the first to raise the issue. One brave ID student challenged his biology teacher as recounted by this atheist student:
There’s a fellow in my class who is quite religious, we both enjoy a good discussion about life. He is a Christian (who believes VERY strongly in intelligent design) while i am a Atheist.
One topic came up in class about how the heart could have evolved from 2 chambers to 3 (and i suppose a 4 chamber heart), our science teacher couldn’t answer the question to which he replied “Than why teach it?” (He often says that, gets on my nerves a bit, but I’d rather let it be).
After class i came up to him and told him I’d have a answer for him, time went on and i forgot about it, but I’d love to answer the question for him. I couldn’t seem to find anything about it in wikipedia or google, so i figure maybe a message board dedicated to science may have the answer.
http://cosmoquest.org/forum/archive/index.php/t-63125.html
Here is the difficulty. The wiring from 2-chambered (fish) to 3-chambered (some reptiles) is pretty difficult. It can’t happen in gradual steps. Not only does the 3rd chamber have to come into existence, there has to be a major simultaneous plumbing overhaul. After that, then you have to account for the different plumbing above for the non-2-chambered hearts. The transitionals would be lethal in each step.
No wonder the biology teacher could not describe the transitional!
PS
1. The evolution from 3-chambered to 4-chambered might not be so bad, but again, what about the wiring? If the chambers are wired differently, then the evolution via slow incremental changes would be precluded. I mentioned earlier the difficulty of evolving from 3-chambered to 4-chambered, but upon further consideration, I think the problem evolving 2-chambered to 3-chambered or the diagram above are more pointed arguments.
2. Apparently 3-chambered hearts are often viewed as having one ventricle, but the Encyclopedia Britanica describes the single ventricle as being 2 (one right and one left), but it doesn’t matter that much when considering the position of the right atrium and other plumbing.
The philosopher, Mary Midgley, nailed (or rather ‘pinned’) poor old Dawkins in a particularly withering put-down, which seems to have absolutely incensed his ‘groupies’.
‘She wrote that she had previously “not attended to Dawkins, thinking it unnecessary to “break a butterfly upon a wheel.’
No wonder Kipling said that the female of the species is more deadly than the male!
Embryology!
Yeah. Alan has it, you don’t need to morph one adult form into another. You have to find developmental pathways can be tweaked in one direction or another. Question like this one don’t make much sense in that case:
“How did those aortas migrate from on ventricle to the other without the transitionals being lethal?”.
You might want to read about lungfish hearts wile you’re at it
Mr. Fox, “Embryology!”
Please do tell how this word, thrown out with such confidence, explains the insuperable difficulty highlighted by Sal? As for Darwin, Embryology is not your friend Mr. Fox!
Notes:
born again: “Please do tell how this word, thrown out with such confidence, explains the insuperable difficulty highlighted by Sal?”
evolutionists have a terrible case of “magic wand syndrome.” So whenever they get in an intellectual bind they’ve developed a strategy to duck and run by using catch words and phrases like “Embryology!” or “Evolution!” or “Mother Nature,” which tend to mentally soothe over logical impossibilities in their own minds, so they hope these words will do the same in yours. It’s their own version of “Goddiidit.”
How does a human zygote get from a single cell to a fully grown adult – no heart to fully functional heart – and all the while remaining viable?
Is this a serious question/analogy? Or perhaps I’m falling for troll bait on a facetious question.
Yes, it’s a serious question. The process happens seamlessly.
Necessity!
Alan Fox:
By design! Also human zygotes are not “viable”- they depend on the mothers.
Add “viable” to the list of words Alan Fox doesn’t understand.
Unguided evolution cannot account for any heart, nor can it account for embryology.
Just sayin’…
Hello, Cantor,
I’m still wondering why you asked that probability question.unfortunately KeithS has been banned for being too clever by half, though I suspect he may still be reading the site and might appreciate your response.
What do you mean by necessity? What drives viruses to reproduce (which is about all they do, given the chance) is an interesting question. What drives (or appears to drive) sentient beings to survive and reproduce? Is it more of the same?
And sunshine and rain make grass grow. I did not think I needed to mention this!
What do you mean by “embryology”?
It’s the process by which multicellular organisms develop from embryos. There’s a whole new (well, quite new) field of study called evolutionary developmental biology (evo-devo for short)that looks at how the process is orchestrated. See wd400 at 3. If you are genuinely interested you may need to venture beyond this site.
Necessity?
Alan Fox:
Only where there is grass.
But anyway, Alan, viable means it can live outside of the womb- I didn’t think I needed to mention that!
Its design.
And if you think keiths is clever, then you have already lost- but we already knew that.
Alan Fox:
And your position has no idea how that came to be. IOW your position is a total wash-out.
Your position cannot account for lungfish…
Darwinian macroevolution would involve countless situations as this about the hearts.
To invoke “embryology” to explain these transitions makes no sense because embryology has to be explained in the first place, and Darwinism is incapable to do it, as is incapable to explain the final stage of the embryo for every species.
This is a key point. What Darwinists don’t understand is they should explain not only the causes of the differences in the adult individuals, but ALSO the differences in their embryo developments. So, in truth, the problem of macroevolution is far more complex than thought. But what’s the problem when one dreams…
Only relatively speaking. I couldn’t quantify it. Like intelligence, cleverness is impossible to quantify. 🙂
Nonsense. Science works very well by chopping up problems into pieces and tackling them piecemeal.
Old news.
The genetic and developmental basis of how multiple heart chambers form has been identified and, indeed, the transformation of a single-chamber heart into a functional multi-chamber heart in tadpoles has been demonstrated – with videos!
FGF signaling delineates the cardiac progenitor field in the simple chordate, Ciona intestinalis
See in particular Figure 7.
That is OK Alan. Your position doesn’t seem to be able to quantify anything. It’s as if it likes be anti-science.
blockquote>If you are genuinely interested you may need to venture beyond this site.
Or not! Thanks for the link, CLAVDIVS.
Of course Alan would say that- he has no choice.
If the blind watchmaker cannot explain embryology, then it is a given that it cannot explain anything that requires it.
CLAVDIVS-
Embryology does NOT help you because you cannot account for embryology. And embryology has nothing to do with transitional forms.
What Alan is referring to:
http://www.fi.edu/learn/heart/.....pment.html
But not so fast, Darwinists!
How can this development happen, it is mediated by a developmental program, not random mutation followed by selection, further it happens under the protection of the mother’s womb. Those stages happen by week 7, but the fetus has zero survival even by week 20 outside of the womb. So to claim that the “transitionals” would survive own is not supported by the evidence.
http://en.wikipedia.org/wiki/Fetal_viability
If one wants to say this looks like evolution, it looks more like front-loaded evolution rather than Darwinian evolution!
So the intermediate stages are not viable while the fetus is being constructed. The intermediate stages are clearly lethal without nurturing and would die in the wild.
A fish with a 2-chambered heart out in the water does not have a mother’s womb and a developmental program to guide the stages.
The transitionals don’t exist in principle in the wild and out in the open. Thus the OP stands.
PS
Because of the suggestion of evolution by the human heart development in the womb, Leo Berg said phylogeny recapitulates ontogeny (the reverse of Haeckel), emphasizing his belief in front-loaded evolution. He argued there are examples where more primitive species in their developmental stages seemed to have anticipatory analogs in future species.
He argued the trajectory of evolution seemed to follow a program like the trajectory of development. Although I don’t share Berg’s views, he was right to say, if there was evolution, it was non-Darwinian but seem to follow a predetermined plan.
Joe @ 25
Epic logic fail.
“If chemistry cannot explain the origin of atoms, then it cannot explain anything that requires atoms.” is obviously preposterous. That is because, even if we don’t know where something came from, we can still observe how it works.
My kids wouldn’t have a clue where iPhones come from or how they are made but they are pretty good at figuring out how to work them without any help at all.
Scordova @ 27
We actually have videos of viable fetal transitionals – see the link @ 22.
CLAVDIVS FAIL:
That has nothing to do with what I said.
LoL! You can observe how it works but you cannot say that the blind watchmaker didit. And THAT is what is being discussed- what can blind watchmaker evolution do.
I bet they know IPhones are DESIGNED and as such work the way they were DESIGNED to work.
They ain’t transitionals! It is development…
Joe @ 30
Yes, we can observe how something works. And when we observe fetal heart development we can see how a simple change in genetic signalling changes the heart from one to two chambers.
THAT is the explanation for the transition that the OP said didn’t exist. Lets grant to you for the sake of this point that the whole developmental process was designed. Nevertheless, the transition is not inexplicable on current knowledge, so the OP was incorrect to suggest so, which was my only point.
CLAVDIVS:
And as far as anyone knows that happens by design.
No, it isn’t. You need to explain how that genetic signaling arose via blind watchmaker processes. And you cannot.
Joe is perfectly right. An individual arises from an embryo development in toto. The embryo development is the causation chain leading to the individual, its final effect. If this causation chain is unknown, the origin of the individual is unknown.
To say that “even if we don’t know where something came from, we can still observe how it works” equivocates the issue. To observe “how it works” and “to explain how it originates from zero” are two different things.
Joe @ 33
Joe, if you run your hands up over your cheeks towards your forehead, you will find two holes filled with jelly. These are called eyes.
Please use them and READ the OP where you will see it claims the transitions between single- to multi-chambered hearts cannot happen “in principle” because the “transitionals would be lethal in each step”.
The OP does not say “there are transitionals, but they require a designer”, which is apparently your position. It says transitionals are impossible, with which both you and I apparently disagree.
So why are you arguing with me?
I know what embryology is.
I did not ask “What is embryology?”
I asked “What do you mean by “embryology”?”
As in, what were you suggesting (claiming?) with your one-word post @2.
Your link was to Ciona intestinalis not a human. Further, “fetal” usually refers to development of embryo inside the mother, which is not the case for Ciona intestinalis.
Did the tadpoles live to adulthood and reproduce identical phenotypes? Not that I could see in the paper, as far as I could tell, the changes were effectively lethal to the formation of a functional adult.
Were the tadpoles able to swim? Did they mature? This looks more like an abortion than evolution of a new creature.
Thanks anyway for the informative links.
niwrad @ 34
There’s no equivocation by me niwrad.
???????????
That’s exactly what I’ve been saying. How something works and how something originated are two different things. We can observe how something works even if we don’t know how it originated, because the two are different things.
And what we observe, in the area of fetal heart development, is that a relatively simple and easily understood change in genetic signalling can cause a phenotypic transition from a single-chambered heart to a multi-chambered heart. Thus, the claim in the OP that such a transition is impossible “in principle” because the “transitionals would be lethal in each step” is refuted by what we can actually observe.
scordova @ 37
Thanks for the response.
I posted that information purely to rebut the claim in the OP that the transition from a single-chambered to a multi-chambered heart was impossible “in principle” because the “transitionals would be lethal in each step”.
Such transitionals are observed not to be impossible in principle, and they are not lethal “in each step”, as claimed.
Embryotic development does not = transitionals.
How many mutations does it take to get an organism with a 4-chambered heart from an organism with a 3-chambered heart?
All Darwinian evolution is “a relatively simple and easily understood [random] change in genetic signalling”. From ameba to man is all “a relatively simple and easily understood [random] change”. Ok, so it is how complexity comes from simplicity. But, to be precise, don’t forget the [random] adjective prescribed by neo-Darwinism.
Sal’s mispresentation that WD400 and what CLAVDIVS picked up on. The genotype does not contain blueprints of adult organisms. How organisms develop from embryos is crucial in understanding evolutionary change.
Alan Fox
Yeah, you (along with the other two) are still not tackling what was originally questioned. Try upping the old reading comprehension, and give it another go by addressing the actual point.
That’s not a controversial statement. In the context in which you posted, it seemed like you were trying to rehabilitate Richard Goldschmidt.
@ cantor:
Much as I had a soft spot for John Davison, I was never swayed by saltation!
Necessity?
Alan Fox:
Then where is it? And does that mean that genetic changes cannot account for the physiological differences observed? If so you have just destroyed your position.
So if organisms develop by design then they evolve by design. I agree.
Alan Fox:
You are swayed by your own personal issues, Alan. Evidence means nothing to you.
Nowhere. There is no blueprint for an adult organism anywhere. It is all to do with local gene switches triggering cell growth, topology, local rules, cell differentiation etc. Big and growing subject.
A human zygote developing into an adult human has not been demonstrated to be a neo-Darwinian macroevolutionary process.
Did someone claim that? Must have missed it! My point was as CLAVDIVS elaborated on. Development of the embryo is how we get adult organisms. Variation in development, itself subject to genotypic variation and selection, will result in variation in the adult.
Of course not, Cantor, but you are missing Alan’s point, I think.
A human zygote remains viable throughout the developmental process.
Therefore it is not the case that a half-heart is as useless as a whole-heart.
Now, clearly, a human zygote and beyond to baby-hood is not a self-sufficient animal, so you are right to object that this does not indicate that a half-heart would be viable in an adult.
However, what it does tell us is that what might seem to be big discrete step between one kind of heart and another, with no viable incremental points is not a safe assumption.
And indeed, in modern organisms, we see lots of kinds of hearts, on a continuum from simple to complex (as is the case with eyes as well). So that alone is evidence that each of those hearts can be (and is) viable in an adult animal.
However, what it does tell us is that what might seem to be big discrete step between one kind of heart and another, with no viable incremental points is not a safe assumption.
And indeed, in modern organisms, we see lots of kinds of hearts, on a continuum from simple to complex (as is the case with eyes as well). So that alone is evidence that each of those hearts can be (and is) viable in an adult animal.
But you are speaking as to what you feel “should” be there and not giving evidence of species, that lived to pass on the novel mutation of the heart, at varying incremental stages.
Feels as though there is much question begging going on.
Indeed a fault of mine. Help me out by restating “the actual point” if it wasn’t about evolution of hearts.
But you are speaking as to what you feel “should” be there and not giving evidence of species, that lived to pass on the novel mutation of the heart, at varying incremental stages.
Feels as though there is much question begging going on.
REPOST EDIT: Forgive my previous typo in formatting.
From the link:
Immediately lethal for 91%, and the lethal for the remaining 9% that don’t reach maturity thus lethal to the lineage. And even then, the experimenters need at least a few coordinated simultaneous changes to the creature.
Of course, if you coordinate several changes simultaneously to get a viable organism — that’s hardly small gradual change! We call those hopeful monsters.
But I’ll clarify the point in the future. Thanks for the criticism.
You are asking detailed scientific questions which is good. However there are better places to get the current state of evo-devo research. Most working scientists don’t post here either because they can’t or because it’s like knocking your head against a brick wall.
Being a laymen, myself, and not knowing your level of expertise, I hesitate to make any recommendations, though here is an on-line journal that might put you on the track.
You said embryology in comment 2. Mutations affecting embryo development may re-arrange parts of an organ, but that doesn’t imply the rearrangement is viable or selectively advantageous.
You argued that changes in development will rearrange parts, but that’s not the same as saying the rearrangements will necessarily lead to a functionally viable lineage.
Problematic to the Darwinian thesis is that the defective mutant will somehow survive selective elimination to get some more defects and somehow survive even more selective elimination, and then get some more defects that make it selectively advantaged. 😯
But for that to happen, the thing has to remain alive in the first place!
The experimenters have proven a lot simultaneous coordinated changes are indicated just to make a viable adult, but coordinated changes are anything but Darwinian, they are hopeful monsters.
And even supposing a transitional lives to adulthood, it’s defective organs are selectively disfavored.
Allan Miller at TSZ put it well:
Wrong, it is necessary, not sufficient. But right in that Darwinists have to hope NS actually doesn’t work for evolution to happen!
Well, I wasn’t really making an argument, just pointing out the common misconception that evolution acts solely at the level of the adult. Obviously we then have the problem of intermediates, as per your example of going from numbers of chambers in discrete steps, which would indeed start to look like Goldschmidt-style saltation. Combine breeding isolation, neotony and embryology and there is more scope.
You initially seemed to be claiming that, when you make your one-word post.
His post was number 22, long after I posted “Necessity”.
That is not a controversial statement.
Neither is that statement, under a charitable interpretation of “genotypic variation and selection”.
I was missing his point when his post was one word long.
Read the thread chronologically Elizabeth.
Who said a whole heart is useless??
OK, fair enough. And my reference to a “half-heart” was a reference to the expression “what use is half a wing”.
Not to worry. If we are on the same page, cool.
Do not be concerned. I am not worried.
scordova
That is a misleading fabrication. There is not a single mention of lethality or death in the linked paper; you just made this up to try to paper over the fact this research falsifies the claim you made in the OP. The paper simply states that 9% of the experimental group developed a heart with two chambers that “can function in synchrony to drive blood flow efficiently through the juvenile body cavity”.
Well thank you for the thank you.
Of course, the paper makes it quite clear that several coordinated changes are not required, just a change in the Ci-Ets 1/2 transcription effector from symmetric to asymmetric activation, which leads to the heart forming multiple chambers.
In any case, whether one or more simultaneous changes is required is irrelevant to the fact that this research blows the OP completely out of the water with regard to the claim that transitions from single- to multi-chambered hearts is impossible “in principle”.
What is more, there are many more examples of research showing such transitions “in principle” – for instance, several reptile’s hearts are transitional between 3 and 4 chambers, some having partially connected ventricles, and some having a single ventricle with an adjustable wall. We also know the important role played by a common genetic program (e.g. T-box transcription factors) in embryonic heart formation in all vertebrates
So to “clarify the point” will you be editing the OP to note that you have now learned its principal claim has been falsified by observational evidence? That would be the proper thing to do to ensure interested persons are not misled.
No, the organism wasn’t viable, you’re misrepresenting the actual outcome, and you have the gall to talk about misleading!
Where are you getting that from, Sal? I’m reading that “some” had “disorganised” hearts but 9% had a functional 2 chamber heart, instead of the usual single chamber.
Where does it say that this was lethal?
Lethal, lethality, unviable appear nowhere in the paper, Sal. Is there another synonym I should look for? Deadly? Fatal?
No luck!
9% had two-compartment beating hearts, the other 91% did not, it did not mean the 91% necessarily died, I misread, thank you for the correction.
It doesn’t say that the 9% died either.
They probably did, because either they ended up on a microscope slide, or ethics approval didn’t allow the researchers to keep the critters beyond juvenile status, but I don’t see anything in the paper that says they weren’t viable.
Actually, even if it did, that wouldn’t be terribly important – the absolutely fascinating thing about that paper is that it suggest that a small step for a genetic sequence can be a giant step for a tunicate’s heart.
Hopeful monsters indeed!
But thanks for the correction, Sal.
Alan Fox writes,
Wouldn’t the blueprint for an adult human organism be contained in the DNA?
Nowhere. Would you prefer I say “fatal to the lineage” or will you prefer I say something like: “this proves a simple mutation in Ciona will create a new creature that lives to adulthood and reproduces and is more reproductively successful than Ciona with one compartment.”
Bouts of asynchronous beating? If a functioning multichambered heart had bouts where chambers weren’t coordinated, this would be bad, and if it lasted for a few minutes, in certain organisms it would be fatal.
The second compartment is liability, it adds plumbing that serves no purpose at best and introduces dysfunction at worst. No mention of successful maturing is provided, that omission of the eventual fate of the embryos is noteworthy. At the very least, lack of mention does not disprove the claim such variation is fatal to the lineage.
You are welcome, it was the right thing to do on my part.
But the title of your OP asks whether transitionals are possible in principle
It seems the answer is yes – that transitional hearts are found in some species; that embryos remain healthy through all stages of heart development; and that a small genetic changes can lead to a functional multichambered heart in one step.
It’s not evidence that it happened, but it’s powerful support for the principle that it could.
Duplication of an existing organ or organ part is hardly spectacular, it is a freak.
The OP dealt with the necessary rewiring to go from single- circulation to the 4 pictured double circulation hearts.
In gong from single circulation to double circulation heart, there needs pulmonary arteries and then they have to be located in correctly. No pulmonary artery or mis-wired pulmonary artery and the organism is dead. But without a lung or gas bladder in the first place there is no need of pulmonary artery, but if there is no pulmonary artery in the first place (or some substitute) there is no need for a lung since the organism would be dead!
That part of the OP stands, and the example of duplicating existing parts in Ciona is not directly relevant….I got drawn into a red herring discussion, and I’ll know better next time how to stay my argument.
The OP stands, I have to specify what intermediates specifically mean in the future, and that should clarify what I mean by lethal intermediates.
I’ll be more specific next time which transitionals in principle I was referring to. Specifically the transitional from single-circulation to double-ciruculation such as those depicted above.
It does seem, from developmental biology, there is a tremendous ability to duplicate organs with the attendant rewiring falling into place. This is sadly the case with Siamese twins or duplicated body parts. The capacity to rewire circulation on the fly seems inherent in biology, but this is not to be unexpected since rewiring on the fly happens when there is serious injury. What we may have witnessed with Ciona is an example of rewiring analogous to rewiring we see in healing.
But this rewiring seems to be constrained to certain limits, not rewiring in terms of going from single to double circulation.
The ability to heal after injury implies somewhere in the organism is information to make copies of the injured parts, thus it is not unusual that a little tweaking or mistake will cause a duplicate organ. This is well known, and we don’t need developmental biologists tweaking genes to get these effects.
The malformed duplicate can be explained as a failed healing or regeneration process or copying mechanism that went awry.
Simple examples in nature:
1. flat worms, split its head, it grows two of them
http://www.britannica.com/EBch...../Flatworms
2. plants and trees, prune them and copies of the leaves and branches continue, but this is natural and common
3. the fourth leaf in a clover
http://en.wikipedia.org/wiki/Four-leaf_clover
even 5,6…56
4.
some sad examples in humans, I feel sorry for those suffering, but it happens:
http://en.wikipedia.org/wiki/Polydactyly
http://www.urologyhealth.org/u.....article=51
The bottom line, even if the Cionas are viable, duplicated organs aren’t examples of the transitionals I was talking about that can’t exist in principle.
In light of the abundant evidence of duplicated parts in nature (some natural such as in plants, and some abnormal such as in humans), the Ciona double heart is hardly spectacular and it doesn’t prove transitionals of the variety I described can exist, it only proves developmental mechanisms can go awry by man-made monkeying and cause the Ciona to make copies of something it shouldn’t.
The researchers are overhyping the significance being able to induce defects that duplicate body parts. That’s not the sort of change that create previously non existent body parts and novel rewiring (such as the double circulation with a lung and pulmonary artery).