Uncommon Descent Serving The Intelligent Design Community

There is “teeth” to ID

February 22, 2006
Intelligent Design
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Chicken will grow teeth when pigs can fly.

Well, better start searching the skies for flying pork—scientists have discovered a mutant chicken with a full set of crocodile-like chompers.

The mutant chick, called Talpid, also had severe limb defects and died before hatching. It was discovered 50 years ago, but no one had ever examined its mouth until now.

The finding made scientists curious whether healthy chickens still possessed the 80-million-year-old genetic pathway for producing teeth………

By making a few changes to the expression of certain molecules in the pathway, the researchers were able to induce tooth growth in normal developing chickens. These teeth also looked like reptilian teeth and shared many of the same genetic traits, supporting the scientists’ hypothesis.

Here’s the citation:

http://www.livescience.com/animalworld/060222_chicken_teeth.html

The difference between genome and phenome can be extravagant. “Front-loading” suggests that there’s a lot to the genome that is not seen in the phenome. This discovery should make for some interesting head-scratching.

Comments
ds, I'm not saying that evolution from complex to simple doesn't happen. It has happened many times, especially in parasites that use the "apparatus" of their host to feed, so energetically costly but unnecessary "equipment" became a selective liability. But there is simply no evidence that this sort of scenario gave rise to bacteria, as you suggested earlier. The oldest known fossiles look like bacteria, so the simplest theory is that they evolved before eukaryotes, which show up much later (about 2Gy I think) as fossiles (but I don't know if one can actually see nuclei in those fossiles. Does anyone know?). I am sticking to that famous razor, although I'll be the first to admit that in many cases (but not the majority of cases) the simplest theory is not the "correct" one.Raevmo
February 28, 2006
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"Let me offer you some friendly advice now. The first thing to do when you’ve dug yourself into a hole is to stop digging. You’re in pretty deep by the looks of it. -ds"

The hole must be in the eye of the beholeder.

You sure caught good ole Craig there redhanded with a huge faux pas. I hope he will get over it.
Anyway, I don't think the organelles have actually escaped from the red blood cell and are now enjoying a free life of their own, as your theory would have it (the thought of the evidence against evolution swimming freely through my veins is almost too much). My guess is they were simply destroyed within the cell, but correct me if I'm wrong. Funny kind of escape, sort of like the arbeit macht frei kind of escape.

If there had been famous experiments that verified once and for all the emergence of life from non-living matter, this website wouldn't exist. On second thought, it probably would. But give it time, those experiments will be done. We can't expect science to solve everything overnight can we?
What did non-living matter "evolve" from? You got me there. I don't know, so there must be a God.

Here's what I think. I think if a blood cell can evolve such that it divests itself of organelles and nucleus to reduce its size and complexity that a free living eukaryote can evolve such that it becomes a smaller simpler organism too but retain just enough DNA so that it, unlike a red blood cell, can still reproduce. And on that note, unless you can convince me otherwise, I think any possibility of you being a constructive member of this blog has become about 1 chance in 10^84. -ds Raevmo
February 28, 2006
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"What? 8-O You think that an unorganized mess of small organic molecules with no particular affinity or stability in polymerizing and no known natural way of concentrating in solution somehow self-organizing into a DNA-based living cell is about the same order of difficulty as an already DNA-based living cell spawning a simpler version of itself? Oooooooooooooooooooookay… :roll: Maybe you’d like to reconsider. -ds"

Honestly, I don't think at the moment anybody is in a position to make well founded statements about the plausibility of organized life emerging from small organic molecules. I believe it must have happened that way because I don't believe in a designer. At least not a "supernatural" designer (aka God). It might well be that life on earth was seeded by extraterrestrials, but then the question is where do they come from? Ultimately, life must have evolved from non-living matter, IMHO. How likely that is, or under what range of conditions it can happen is a totally open question as far as I am concerned. But it is a much more exciting and interesting scenario than that of a designer, which I find, frankly, boring.

Oh, well now we're getting scientific. If it's boring it can't be true. That's called Jockman's Brassier or something like that, a fundamental bit of scientific philosophy. Life must evolve from non-living matter. I seem to have forgotten about the undoubtedly famous experiment that verified life must evolve from non-living matter. Could you refresh my memory there? But what did non-living matter evolve from? Mustn't that evolve from supernatural matter? I think that was a conclusion of the same experiment I can't remember.

Say, my catching Craig Venter's faux pas about all our cells having DNA brings up a good point. Immature red blood cells have a nucleus and organelles but in mammals they've evolved into a mature form that loses its organelles and nucleus. Sort of like my hypothetical amoeba that spawns a bacteria. So not only isn't it farfetched, a similar bit of descent with modification is happening in your bone marrow right this very instant! HA!

Let me offer you some friendly advice now. The first thing to do when you've dug yourself into a hole is to stop digging. You're in pretty deep by the looks of it. -ds

Raevmo
February 28, 2006
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"Please excuse me for my presumption. Do you believe that cells were created by an intelligence or somehow self-organized from inanimate chemicals? I didn’t imply abiogenesis happened in one step nor did I imply that organelles evolved into free living cells in one step. So again, if you believe that chemicals evolving into cells isn’t farfetched I don’t see how you can say that organelles that already contain DNA couldn’t evolve to be free living. You appear to be checkmated on this farfetched issue. I suggest you display some maturity and concede the point. -ds"

OK, I concede that in absolute terms the farfetchedness that organelles evolve to be free living is approximately in the same ball park as the farfetchedness that chemicals evolve into cells. However, I am done and you still have to explain where the amoeba came from in the first place. Your answer is of course the designer, but I find that an unsatisfactory initial condition.

What? 8-O You think that an unorganized mess of small organic molecules with no particular affinity or stability in polymerizing and no known natural way of concentrating in solution somehow self-organizing into a DNA-based living cell is about the same order of difficulty as an already DNA-based living cell spawning a simpler version of itself? Oooooooooooooooooooookay... :roll: Maybe you'd like to reconsider. -ds

P.S. I find the idea of a complex cell magically appearing from an unknown chance mechanism to be an unsatisfatory initial condition. So I guess we're even on the unsatisfaction. It's more satisfactory to me to presume that intelligence and life originated somewhere else long before it did here and evolution on earth proceeded from a complex beginning. Everything in evolution makes perfect sense if we start from a complex beginning. Given the immense size and age of the universe and the fact that intelligence is a known quantity in at least one instance (proof of concept) it isn't unreasonable to presume it didn't begin here. -ds Raevmo
February 28, 2006
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"Let me get this straight. It is not farfetched to presume that cells somehow evolved from an undescribed chemical soup of some sort but it IS farfecthed to presume that an organelle could evolve into a free living cell? I think your farfetchedness detector needs to go into the shop for repair. -ds"

Well, I didn't say that cells somehow evolved from an undescribed chemical soup. Perhaps your put-words-in-someone's-mouth-generator should go to the same shop. You make it sound as if there are people out there who believe that cells evolved de novo from soup just like that -- in a single step. Nobody believes that. There are quite reasonable speculations about a more gradual evolution from self-replicating molecules to very primitive cells to more advanced cells. These theories cannot be properly tested yet, but give it some time. I think that a lot of progress will be made in this field in the next couple of decades. We are intelligent designers.

Please excuse me for my presumption. Do you believe that cells were created by an intelligence or somehow self-organized from inanimate chemicals? I didn't imply abiogenesis happened in one step nor did I imply that organelles evolved into free living cells in one step. So again, if you believe that chemicals evolving into cells isn't farfetched I don't see how you can say that organelles that already contain DNA couldn't evolve to be free living. You appear to be checkmated on this farfetched issue. I suggest you display some maturity and concede the point. -ds

Raevmo
February 27, 2006
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"Furthermore, some modern amoeba have multiple nuclei. It isn’t out of the question that some of these multiple nuclei evolved first into organelles then into free living bacteria. -ds"

That seems a bit far-fetched. An organelle that evolved from a second nucleus would be very unlikely to have the capacity for independent survival once it somehow escaped from its host.

It appears much more likely that some bacteria lost the rigid cell-wall and evolved phagocytosis, enabling engulfment of other bacteria that later became mitochondria, who later lost the capacity for independent survival. Where are those bacteria with phagocytosis now, you ask? Dunno. Outcompeted by eukaryotes?

Let me get this straight. It is not farfetched to presume that cells somehow evolved from an undescribed chemical soup of some sort but it IS farfecthed to presume that an organelle could evolve into a free living cell? I think your farfetchedness detector needs to go into the shop for repair. -ds Raevmo
February 27, 2006
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"All we have are some fossilized shapes in 2.5 bya strata that sort of look like the shape of modern bacteria. Amoeba, which can be incredibly large cells with incredibly large genomes, have no characteristic shape to recognize as they’re amorphous blobs. -ds"

Right. Life like that probably wouldn't fossilize. Bacteria have relatively solid cell walls in addition to membranes. However, amoeba are eukaryotes, having a nucleus and organelles some of which are in fact ancient symbiotic bateria (even with their own DNA).

Mitochondria, chloroplasts, and centrioles are the only organelles with DNA AFAIK. While the endosymbiotic theory makes good sense for how these came to exist in eukaryotic cells it doesn't make sense that a bacteria engulfed a bacteria to become a eurkaryote. Bacteria don't eat like that. Amoebas however do. It makes perfect sense that nucleated amoeboid cells engulfed bacteria which became mitochondria, chloroplasts, and centrioles. I fail to see how endosymbiotic theory points to bacteria coming about before eukaryotes. The definition of a eukaryote is a cell with a nucleus. Organelles aren't part of the definition. Furthermore, some modern amoeba have multiple nuclei. It isn't out of the question that some of these multiple nuclei evolved first into organelles then into free living bacteria. -ds Raevmo
February 26, 2006
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"Who says the LUCA was a bacteria and what evidence do they have to support it? -ds"

The oldest known fossilized life forms look like bacteria. That's standard textbook stuff.
Presumably however, the real LUCA is even simpler than bacteria (bacteria are FAR from simple), and perhaps too small to leave any detectable fossiles. Wouldn't it be great to check far away planets for such LUCA-like life? Most likely outside our solar system, although the odds that there is primitive life on Mars are pretty good.

All we have are some fossilized shapes in 2.5 bya strata that sort of look like the shape of modern bacteria. Amoeba, which can be incredibly large cells with incredibly large genomes, have no characteristic shape to recognize as they're amorphous blobs. -ds Raevmo
February 26, 2006
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DaveScot said:
"If we begin our descent with modification from a universal common ancestor that already had all the diversity in life we see today locked inside of it waiting for the right time to emerge then all the so-called gaps in evolution are filled except the gap of where that complex seed or egg or LUCA came from. Given the size and age of the observable universe it isn’t unreasonable to presume that life didn’t begin here - that it began elsewhere and arrived here in an already advanced state."

Interesting idea. Except that bacteria clearly don't have enough DNA to code for all that diversity. Or are you saying that more "advanced" life arrived while there already were bacteria?

Who says the LUCA was a bacteria and what evidence do they have to support it? -ds

Raevmo
February 25, 2006
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Just curious. I saw the picture of the unborn bird with mutant teeth. Can someone tell me if these are just protruding extensions or actual teeth? They say they are like crocodile teeth. Does that mean the mutant chickens teeth were thecodont (set deep in dental sockets and not fused to the jaw) ? If so, interestingly enough, they also share this trait with: toothed whales & dolphins, pliosaur, mammals but not with many other reptiles. Crocodile teeth are also replaced when lost (up to 40 times). Would this mutant chicken be able to replace its teeth ?rb
February 23, 2006
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Here's a quote: "The discovery shows that fur and modern skin structures and warm-blooded metabolism originated very early in mammals. "Hair keeps us warm, and sweat glands help us to dissipate heat, so skin is part of the adaptation to constant body temperature," Luo told New Scientist. "This is a pretty amazing find," Sues told New Scientist. What excites palaeontologists is the new-found diversity and complex evolutionary history of early mammals – a group previously known mostly from scattered teeth. More complete fossils have been very rare. "Traditionally, Mesozoic mammals were not the path to glory," says Sues. Journal reference: Science (vol 311, p 1123)" Are we getting ready to discover the "Jurassic Explosion"?PaV
February 23, 2006
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Charlie: great comment last post. This is from New Scientist: http://www.newscientist.com/channel/life/dn8769.html If you have a 'mammal' with fully-formed 'mammalian fur', then it would seem to add strength to an argument that birds 'evolved' (showed up on the scene) early, and the feathers appear in the modern form even 164 mya.PaV
February 23, 2006
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Geoff, thanks for the article on Feduccia. What isn't mentioned in your article (but as everyone knows, and is also relevant here) is that 150 million years ago the flying feathered bird, Archaeopteryx, also had a toothy grin.Charlie
February 23, 2006
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"This discovery should make for some interesting head-scratching."

Could someone take a second and explain who will be scratching their head and why? This seems like a very clear-cut example of what the ToE predicts and it's not exactly a secret that small genetic changes can result in large physiological changes.

What am I missing?

Evidently you missed everything that was written in this thread. Your comments are getting pretty boring. Consider yourself warned. -ds

SailorMon
February 23, 2006
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Goeff: If you want to get into that discussion--dinosaurs to birds--be prepared to duck (no pun intended). That is a wild discussion. Talk about veins sticking out in necks....whew!PaV
February 23, 2006
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ds wrote: "NeoDarwinian theory suggests that the genes that produce teeth in chickens, no longer being used and therefore not under selection pressure, should have drifted into irretrievable disrepair over the course of 80 million years. This begs the question of how or why they are still functional." Good point, Dave! I hadn't thought of that angle; but you're right. It reminds me of the article in New Scientist where they reported on the reaction that took place among professional biologists at a some Proceedings seminar. They took out about a million (10^6) nucleotide bases that were 'highly conserved' and ended up producing rats that were indistinguishable from normal rats, thus destroying the notion that NS "conserves" that which is most essential to life. The response in the room was that of gasping biologists. When I read that article, I told my sister, "Darwinism is dead." It's really just a matter of time.PaV
February 23, 2006
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Speaking of birds/dinosaurs: http://www.sciencedaily.com/releases/2005/10/051010085411.htmgeoffrobinson
February 23, 2006
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Has anyone here read about the Ciba-Geigy effect in which the anscestral forms of modern plants/animals are grown by exposing the seed to an electrical field between aluminum plates? The pharmaceutical chemical company has a patent on such a device and was able to produce corn, wheat, fish, etc. which had long been extinct. This may or may not have anything interesting to say about this question. I am not smart enough to know at first glance, but the technique is quite legit, and can easily by reproduced. Apparently, Ciba-Geigy abandoned the project because it was seen that anscestral forms of corn and wheat are far hardier and more disease-resistant than modern forms, thus negating the need for the chemicals the company sells.tinabrewer
February 23, 2006
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Fross: Thanks for the link. I'm a little familiar with feather evolution (Prum and Brush wrote a definitive article on them in the last two years), and with fossil evidence tying dinosaurs with 'feathers'. It was sort of with that in mind that I posted this article. One of the arguments that paleontologists have is whether certain forms are modern birds or not. One of the criteria that they use is the presence or absence of teeth. I just thought this threw a bit of a monkey wrench into it all. We need to have a little fun here every once in a while.PaV
February 23, 2006
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Hey PaV, have you seen this? While I don't really understand your frontloading explanation, I feel that this may somehow fit into it. :) It does involve chickens and crocodiles, so it's on topic. http://www.dinosauria.com/jdp/archie/scutes.htmFross
February 22, 2006
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Is the point that the info pre-existed? Then you get different shuffles and some of that info, previously hidden, comes to the fore?

A loss of info or hidden info and not new information from random mutation?

Or am I missing the point?

I believe you're getting the point. There may still be some random chance involved. The deck may be stacked so that new hands emerge in a predetermined order or the shuffle and deal may be random. Front-loading presumes at a minimum that random mutation isn't adding new cards to the deck. Random mutation appears to be making cosmetic changes to the cards (variability in dogs is a good example of cosmetic change) and this is what we call microevolution. In engineering we call small adjustments like that "tweaking" the design. -ds geoffrobinson
February 22, 2006
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The platypus is a wonderful example of how the shuffle and deal works as it represents a different mix of reptilian features than either birds or mammals inherited. -ds

Are you saying natural selection is the force that drives which way the cards get played?

No. But it might determine which hands are winners and which are losers at any particular point in time. If chickens still have teeth lying about in their genome unexpressed what else might they have? What might WE have in ours? We have amphibians that could regrow lost parts in our ancestry. Is that ability still lurking in our genome? What could cause it to go from unexpressed to expressed?

Stem cells in a single organism undergo descent with modification to become many different cell types organized into many different tissue types organized into many different organs. None of that is random. It's all a predetermined sequence and the external environment has little to do with it other than providing triggers to progress to the next stage. The stem cell is replete with unexpressed complexity. Now when we see teeth all of a sudden pop up in a bird it means that chicken stem cells not only have all the potential we know about, but things we don't know about because it isn't expressed at all.

Now imagine if you will a universal common ancestor that is like a stem cell - filled with potential, programmed to unfold in a certain way, with potentials that may or may not be expressed in any particular species. If we begin our descent with modification from a universal common ancestor that already had all the diversity in life we see today locked inside of it waiting for the right time to emerge then all the so-called gaps in evolution are filled except the gap of where that complex seed or egg or LUCA came from. Given the size and age of the observable universe it isn't unreasonable to presume that life didn't begin here - that it began elsewhere and arrived here in an already advanced state.

All the direct and indirect evidence makes sense in this scenario. Nothing is a better fit and it draws on no theological suppositions whatsoever. -ds

Doug
February 22, 2006
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Doug, I just wanted to say that nothing in science is proven. Absolutely nothing. But, it seems to be evidence supporting the idea of a common ancestor. Unless someone here can help me understand otherwise.danb
February 22, 2006
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This is evidence of back-loading, not front loading. Teeth are ancestral to chickens (in fact, coincidentially enough, they are quite similar to the teeth alligators, one of a chicken's closest non-bird modern relations): there's no evidence that there is some sort of future plan for a toothed chicken that is playing out. Did you miss the part about the mutation that exposes the teeth being fatal, or how the expression pathway was once functional, and is now broken/supressed?

Why is it that atavisms always seem to fit evolutionary history? Why do humans only develop primate atavisms, but never cetacean atavisms, and vice versa? It seems like even designers as clumsy and ill-informed as ourselves can make lateral gene transfers (i.e. growing mouse molars in chickens), but we never see traits jump like that in nature. The pattern instead fits the stricter constraints of evolutionary descent with modification.

No, this is evidence of front-loading. Think of the genome as a deck of cards and broader taxonomic groupings as hands that are dealt from the deck. The deck was once large enough in one or more common ancestors to contain all the features that any of its descendents ever had. Macro-evolution then proceeds not as the gradual accumulation of small accidental mutations but rather as the instantaneous shuffle and dealing of a new hand. John Davison (see sidebar) has hypothesized a mechanism he calls semi-meiosis that can deal a new hand in a single generation producing fertile offspring (of both sexes for sexually reproducing organisms) of a species different from the parent. This is in total agreement with the indisputable testimony of the fossil record which reveals not gradual transitions but the sudden appearance of broad new taxonomic orders. The platypus is a wonderful example of how the shuffle and deal works as it represents a different mix of reptilian features than either birds or mammals inherited. -ds plunge
February 22, 2006
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I fail to see how this evidence supports intelligent design at all. Anybody want to spell it out for me? It seems like it supports the hypothesis that birds evolved from ancient reptiles.

"By making a few changes to the expression of certain molecules in the pathway, the researchers were able to induce tooth growth in normal developing chickens. These teeth also looked like reptilian teeth and shared many of the same genetic traits, supporting the scientists’ hypothesis."

It doesn't support intelligent design, per se. It raises questions and highlights the fact that large phenotypical variation can lie dormant for 80 million years and then emerge in a single generation. It's supportive evidence for saltation. And of course saltation fits wonderfully with the fossil record, a record which doesn't fit at all well with the NeoDarwinian fairy tale of large change being the result of accumulation of small changes. -ds danb
February 22, 2006
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So, does this prove that they have a common ancestor?

It doesn't prove anything. It strongly suggests that chickens have an ancestor that had reptilian-looking teeth. It also suggests some other things. NeoDarwinian theory suggests that the genes that produce teeth in chickens, no longer being used and therefore not under selection pressure, should have drifted into irretrievable disrepair over the course of 80 million years. This begs the question of how or why they are still functional. A major objection to front-loading theory is that any unexpressed genetic information would be subject to neutral drift and its function thereby destroyed. Well sir, it would appear the unexpressed information for teeth wasn't destroyed in 80 million years of birds not having any teeth. What's up with that? -ds Doug
February 22, 2006
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"Just that in the atheistic worldview frontloading is the existence of a set of equations that determine possibilities." Of course equations require a designer as well and merely push the issue of ultimate origins back a step. But hey, this thread is about chickens wif teef.Scott
February 22, 2006
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Well it would appear to be evidence of common descent for one thing.

Agreed. -ds ftrp11
February 22, 2006
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