Do organs, like the heart, have a common ancestor?

[DJ_Ghost]

All this says is that the theory of gravity is weaker than the theory of evolution. However, it does not make the theory of evolution any stronger. It's kind of like saying "You should go out with me because that guy is uglier than I am."

It always confuses me that evolutionists will continue to reiterate this point as though it has some sort of useful meaning. Ok, so the theory of evolution is "less weak" than the theory of gravity. So what?

The point is creationists will accept gravity without question but keep saying “evolution is only a theory”. The reason people keep bringing up the gravity analogy is to demonstrate the innate inconsistency in the creationist standpoint and to illustrate how they will cheerfully misrepresent the term “theory” in scientific sense. If you take careful not the evolution/gravity comparison is only brought up when some one tries to make the claim that a theory isn’t worth taking seriously because its “only a theory”.

Ghost

 

[Cirbryn]

its a pleasure to read and have an opportunity to respond to such intelligent posts.

Thanks, particularly since the link I provided to the discussion of the GLUD2 gene was incorrect. I’ve since fixed it.

I understand your point. my contention is not in what actually occurred, but what process governed those events and if the TOE really has reliable scientific support. It seems to me that the TOE has a series of interpolation from available data that is not scientific nor necessarily correct.

I have read many on this forum and all around call the TOE 'scientific fact' or belittle any who question its validity. I have yet to see any compelling evidence that natural selection was the cause of how organisms are the way they are today.

I guess I don’t understand what you think would be compelling evidence and why. I know the gravity analogy’s been done to death, but would you consider the evidence compelling that the stars and planets we can see without telescopes are moving relative to each other due to the influence of gravity? Obviously the effects of gravity have been observed on a small scale – microgravity some might call it, but can we really extrapolate that to the movement of the stars? Sure, we’ve checked some nearby stars and planets here and there, and found general agreement, and we were able to predict the existence of Neptune and Pluto based on differences between the observed movements of Uranus and those predicted by the theory of gravity, but is that compelling? For one thing, we still can’t describe exactly how the orbit of Uranus is deflected by Neptune and Pluto. Two or more planets orbiting around the sun constitute a 3-body physics problem for which there are not enough conserved variables to allow planetary locations to be predicted. See here . For another thing, the second law of thermodynamics shows us that perpetual motion machines are impossible, yet what is our current model of the solar system if not a very large perpetual motion machine? Finally, up until very recently both science and the Christian Church (and probably Islamic teaching as well, though I don’t know) were in agreement that the stars were fixed in place and did not move relative to each other. Admittedly, some small movements have been detected recently in the nearby stars, but how can we extrapolate such tiny observed displacements to the idea of fundamental shifts? Or suggest that gravity, which we observe on Earth on a much smaller scale, is responsible? Perhaps the stars are just varying slightly from the original positions in which God placed them, due to the Fall or some such thing.

I could go on. In fact if I ever get the time I think this analogy deserves its own thread. But you probably get the idea: Generally speaking, while it’s possible to construct arguments to bring even the most basic scientific understandings into question, the evidence for both evolution and gravity is compelling because it is constantly being corroborated by new evidence. We are constantly using the theory of gravity to plot the paths of moons, asteroids, space ships, etc, and so long as we don’t try to get too precise over too long a period the objects have behaved as our understanding of gravity says they should. The nearby stars do as well from the extent we’ve been able to watch their movement. There is therefore no reason to think the stars are limited in their motion. (Also, there isn’t anything actually wrong with perpetual motion machines; you just can’t use them to perpetually do work). Regarding evolution, evidence keeps coming in from numerous unrelated disciplines: breeding studies, biogeography, paleontology, taxonomy, comparative physiology, ethology, ecology, plate tectonics, climatology, physics (for radioactive dating), genetics, genomics, molecular biology, proteomics; it all points to the same thing. Just take a casual stroll through 29+ Evidences For Macroevolution (here) (which seems to be quite a good article, despite using the word “evidences” as a noun). If evolution were incorrect we should be getting more and more evidence that doesn’t fit the model, not more and more fitting in perfectly. Much of this evidence, ERVs for instance, wasn’t even heard of when I was in grad school.

there must have been some point where "switchover" stage occured, i was curious to know if there is any supporting evidence that this ever happened. or is it conjecture based on available data, as in the lungfish etc.

Glenn Morton has an excellent page showing the fossil “progression” currently known (here ). The reason I put “progression” in quotes is that (just as now) at any given point in the past there are likely to be some species retaining ancestral characteristics and some with more derived characteristics, so while there is no reason not to believe a progression occurred, it’s hard to say exactly which species were our ancestors and which were not, and it would be a great stroke of luck to find evidence of the exact species to switch from gills to lungs. Based on Glenn’s website, two early transitional amphibians (Ichthyostega and Acanthostega) had both lungs and gills, so a candidate species for losing the gills might be Pederpes finneyae. Since the site doesn’t mention them either way, my guess is they can’t tell from the available fossils whether Pederpes had gills or not. It was transitional in other ways, however, and later amphibians are referred to by the site as “fully evolved” which assumedly means they had no gills when adult. This site has much of the same information, but points out that much of it has come in the last two decades.

I have not appealed to any precepts of creationism in this thread. i am not attempting to validate nor invalidate the theory based on creationism. I am just holding it to the scientific standard which it claims to adhere to.

Fair enough. I’m not aware of a specific standard for scientific theories, though, other than that they should help explain observed phenomena (or at least help predict them) and that they should be falsifiable. You’ve claimed that evolution can’t be falsified, but I don’t understand why you think that. Things that would falsify evolution, or at least call it seriously into question, include seriously conflicting or impossible species trees as drawn using data from different sources such as taxonomy, the fossil record, genomics, or ERVs; the discovery of a “kind barrier” that evolution can’t cross, such as the Creationists keep talking about but failing to demonstrate; the natural development of a structure or behavior in one species for the sole benefit of another species; a hodge podge of species with ancestral and derived characters all through the fossil record, rather than in an orderly progression with sufficient time between them for the characters to have evolved; etc.

 

[gluadys]

and it would be a great stroke of luck to find evidence of the exact species to switch from gills to lungs. Based on Glenn’s website, two early transitional amphibians (Ichthyostega and Acanthostega) had both lungs and gills, so a candidate species for losing the gills might be Pederpes finneyae. Since the site doesn’t mention them either way, my guess is they can’t tell from the available fossils whether Pederpes had gills or not. It was transitional in other ways, however, and later amphibians are referred to by the site as “fully evolved” which assumedly means they had no gills when adult. This site has much of the same information, but points out that much of it has come in the last two decades[/COLOR].

One reason why you won't find much on gills changing to lungs is that they didn't. People often suppose that they did because both are used to process oxygen. The earliest fish had both gills and lungs. What they did not have was a swim bladder as most modern fish do. Stephen J. Gould suggests that the modern fish's swim bladder is a modified lung, now used only for regulating bouyancy and not for respiration.

Meanwhile, in terrestial animals, gills were not modified into lungs (no need since these animals had already inherited lungs from their lung-fish ancestors) but into structures in the jaw/throat area. In mammals, part of the jaw structures became the bones of the middle ear. So we still have our "gills" too, but they are no longer recognizable as such, nor do they have a gill function anymore. We only know their origin from our embryological development, which shows us that these ear/jaw/throat structures develop from the same pharyngeal pouches that become gills in fish.

 

[Cirbryn]

One reason why you won't find much on gills changing to lungs is that they didn't. People often suppose that they did because both are used to process oxygen. The earliest fish had both gills and lungs. What they did not have was a swim bladder as most modern fish do. Stephen J. Gould suggests that the modern fish's swim bladder is a modified lung, now used only for regulating bouyancy and not for respiration.

Yeah, it's hard to tell with the wacky way these posts are threaded, but I was actually just pointing out myself that gills didn't evolve into lungs in the post prior to the one you commented on (Post 69). I didn't know about the lungs coming first argument though. I suppose one could call an outpouching of the gut a primitive lung or a primitive swim bladder as one saw fit; in a freshwater fish at least. You wouldn't expect a marine fish to need a lung, since it's not often going to find itself in an evaporating pool.

Meanwhile, in terrestial animals, gills were not modified into lungs (no need since these animals had already inherited lungs from their lung-fish ancestors) but into structures in the jaw/throat area. In mammals, part of the jaw structures became the bones of the middle ear. So we still have our "gills" too, but they are no longer recognizable as such, nor do they have a gill function anymore. We only know their origin from our embryological development, which shows us that these ear/jaw/throat structures develop from the same pharyngeal pouches that become gills in fish.

Yep. Here's a link . Apparently the supports for the first gill arch evolved into upper and lower jaw bones in fish, while the support for the second arch evolved into the "stirrup" bone in the middle ear of early reptiles. The back-most bones of the jaw then evolved into the hammer and anvil bones in mammals. Cool stuff!