This entry will once again focus on deception from the Discovery Institute.
Darwin's Homology Problem?
In this video, DI tries to make the case against evolution by stating that homology doesn't always indicate common ancestry. Of course it doesn't, Richard Dawkins discussed this in his book The Blind Watchmaker over ten years ago. His answer was that biochemical and genetic similarity must be present, not just physical similarity.
They begin by talking about the Australian wolf. It has a lot in common with North American wolves, yet no one thinks the two share a recent common ancestor. Is this a problem for evolution? No. DNA Tests have confirmed Australian Wolves to be more closely related to their fellow Marsupials rather than Placental Wolves.
They continue to illustrate their point using the Wasp and the Fruit Fly. They tell us that different genes are responsible for forming the body segments of each one. I suspect that this is not true, however. Proceedings of the National Academy of Science published a paper that stated that the genes responsible for development ("homeobox" genes) were very similar between the honey bee and the fruit fly. The honey bee belongs to the Order Hymenoptera as does the wasp.
They go on to discuss how the gut develops from different tissues in the Lamprey, the shark, and the frog. Talk.Origins provides the answer on this one:
"We now know that organs can be stimulated to grow in many parts of the body (such as eyes growing on a fly's wings) simply by ensuring that the proper signalling chemicals are present. Thus homologous organs arising from different areas may result simply from mutations in where signalling proteins are expressed."
In another video they drag up the ancient issue of Haeckel and his infamous embryo sketches. I do not think that these embryos are used in many textbooks nowadays. For one thing, I examined my brother's textbook and found only correct drawings of embryos. For another, Randy Olson, in his film "Flock of Dodos", showed that textbooks simply do not use these embryos any more. For a third, Kenneth Miller corrected the fake embryo drawings in his textbook nearly ten years ago.
UPDATE: I have posted an update to this clarifying some of what I stated, and responding to a comment left about this entry.
11 comments:
Homology is defined by common ancestry. If structures really are homologous, that means they are derived from an common ancestral structure.
What creationists really mean is that 'similarity doesn't imply homology'.
My opinion is that homology can indicate common ancestry, but it depends on whether the similarities are biochemically similar. It would also depend on whether or not the structure could be the product of convergent evolution. Two shells could evolve the same shape, yet not be related, so that similarity would be worthless.
Homology is a particular form of similarity. Homoplasies (such as analogy) are another. The only difference is that homology is caused by common descent, whereas analogy is caused by convergent evolution and other homoplasies are mere coincidence.
See: http://wiki.cotch.net/index.php/Homology
I assume by "Australian Wolf", you're referring to the thylacine.
"DNA tests have confirmed Australian Wolves to be more closely related to Marsupials rather than Placental Wolves."
What? To say that a thylacine "related to marsupials" is like saying a dog is "related to placental mammals", or that "a lump of granite is like a rock".
A dog is a placental mammal.
Granite is rock.
A thylacine is a marsupial.
You don't need DNA to prove that, any more than you needed to wait until DNA testing was available to classify dogs as placental mammals.
(I presume you believed that dogs were placental mammals already, right?)
DNA evidence does show that thylacines are closely related to other marsupials, but that just supports the evidence that was already there. There's plenty of evidence that thylacines are also quite different from wolves (the pouch is a dead giveaway, for starters, but there are plenty of features that are like other marsupials and unlike wolves).
Convergent evolution is not in any way evidence against evolution - in fact it's dramatic evidence for it - species that fill similar environmental niches often generate similar adaptations to the environment. If eating meat becomes a big part of your diet, you start seeing adaptations in teeth, jaws and gut, as well as a host of other places... because the creatures that had displayed a little of those kind of adaptations were better able to survive. If you have teeth that are flat and designed for grinding, you won't be able to get meat off a carcass nearly as well as a competing animal that has pointier, sharper teeth. You'll eat less and so your rival will have more offspring... and so slightly pointy and sharp teeth become relatively more common. Even superficially different-seeming carnivores tend to share a host of features.
Efrique,
I am aware that thylacines are marsupials, and more closely related to other marsupials. Discovery Institute is NOT.
My point is that if evolution were not true, the thylacine could be more closely related to placental wolves.
Watch the video, because they bring up the Australian Wolf and try to use it as evidence against homology.
My point was to refute them at that.
Quote: "If eating meat becomes a big part of your diet, you start seeing adaptations in teeth, jaws and gut, as well as a host of other places..."
Okay, track with me just a little bit if you please…
Are you saying that the cells in the body send a message to the reproductive system suggesting that it should change things a little because of its slight inabilities (they would be very slight)? Or are you saying that because of the copying errors (mutations) of some animals' reproductive organs, animals with the freakin awesome defects may reproduce those errors, making it awesome for their offspring as well? Because, if the cells aren't communicating with the reproductive system and trying to make a change, then you just have a system of cells trying to reproduce the same blueprint every time, right? Why would that blueprint change if cells have a set function and only by error do they make something slightly different? An error doesn’t reprogram the cells from that point on. Any major mutation is usually corrected in the next generation because the cells have a blueprint that doesn't seem to work right if you change it at all. And if you could change the blueprint slightly and screw up a fruit fly's life, why can't you keep progressing until you have a new specie? They have screwed up the lives of a number of fruit flies and have more or less established the boundaries of the blueprint errors rather than cross them. No new specie has been created at all. Now I’m not saying this is solid evidence for anything, but if it doesn’t make since, it’s usually because it’s not true. So how am I supposed to approach this subject without a logical explanation to start out with? I know of a women who was born without arms (a mutation or copyist error) and she could do things with her feet that monkeys couldn’t much less a human. Her children all had their arms and couldn’t do anymore than anyone else could with their feet. No one in her family as far back as she could go had ever been born without arms. This would be a good time to apply your explanation… but it’s crap. Copyist errors don’t improve structures and they definitely don’t redesign the blueprint. They’re errors.
Quote: "...because the creatures that had displayed a little of those kind of adaptations were better able to survive. If you have teeth that are flat and designed for grinding, you won't be able to get meat off a carcass nearly as well as a competing animal that has pointier, sharper teeth. You'll eat less and so your rival will have more offspring... and so slightly pointy and sharp teeth become relatively more common."
What?! Okay, going back to the logic thing again; (I’m not mocking or trying to pick apart an idea here. I feel these are valid questions that haven’t been answered. I’m not a big fan of AIG either so don’t try that form of rebuttal.) If they have grinding teeth, they could always eat what they’ve been eating for presumably millions of years to supplement their diet, leaving them more adaptable than the defective members of their specie. And I don’t see how even an eighth of an inch less tooth length could stop them from eating just as much as the defective members. Even if it were a rabbit carcass; they couldn’t eat that added half an ounce that was closest to the bone? So if I can’t get that last bit of meat on my ribs I should have reason to believe I’m being phased out by Mother Nature. And how does that affect their reproducing ability? That’s what I want to know.
All these would be good explanations if there were extreme leaps in evolution, or even if evolution had been proven objectively already, but your explanations don’t really make since with the, “slight errors in the specie’s blueprint”, much less give any “cause” for the trans-specie evolution “effect”; not logically anyway.
Those are assertions, I know, but incredibly logical assertions and easier to believe than your assertions which are simply forcing a theory on an otherwise working hypothesis.
Do you have a little better explanation that establishes trans-specie evolution? That would be nice to read.
Sam,
What are you talking about?
Are these quotations from anything I have written?!?!
No, I'm sorry. They are quotes from the comment left here by "efrique" (last paragraph). I just thought his assertions were on the edge of philosophy and thought I'd probe the conversation for a more objective answer. I didn't consider that this may not be a board for conversation between the commentators, but rather conversations between the commentators and the poster. If I have made a mistake, excuse me.
Anyway, I believe that if evolution were true, we would have more transitional fossils than we do. A museum in Chicago boasts over a million fossils alone, meaning we have tens of millions of fossils, all of them a random sample and we have maybe a hundred very ambiguous fossils that are heralded as transitional forms.
I've been to Talk Origins website and I've had this debate in many forums now and not one person is able to show some evidence that can be observed. Instead, they make dogmatic statements with religious fervor and they're never really able to see the flaw of their argument. I understand that evidence is lacking from both sides, but what I don't understand is how they can perpetuate their dogmatic assertions based on so very little fact.
These are serious questions that I have and would be glad to see someone answer them. But atheists usually revert to ad hominems, names and other circumstantial evidences that can also be explained by the mechanisms of creation.
So I'll just say, "If evolution were true, history would bear it out."
Check me on it. Look for transitional forms. You'll find one or two very good sounding arguments, but ask yourself, "Does the evidence really support this, or can it be explained some other way?" If it can be explained another way then people are merely interpreting evidence through their preferred mechanism.
If I sought to prove a world wide flood I could point at the evidences all over world but they really wouldn't be convincing to someone who doesn't buy the Noah's ark story.
When it comes to proving and disproving evolution as a whole, you have to question the evidence from the outset; "Does history bear it out through palaeontology?" If historical evidence is barren then you can't even proceed to the next questions of homologous structures, homologous genes, geology, and microbiology; the latter three being equally damaging to evolution as palaeontology.
Maybe you can add to the masses of evolutionists and offer up some new evidence, but as for me, I have a strong reason to believe evolution is only a theory that was tried and failed and so, became a religion instead. Who knew?
Sam,
I have a whole series called "Evolution for creationists"
It is over to your right just below "The Files AiG Doesn't Want you to read".
Try checking out Part 1 and tell me what you think.
There is also an entry I wrote called "Smooth Fossil Transitions".
It was posted this month.
Okay, thanks. The work week is starting back up so it might take me a little bit to get back to you. But I fully intend on looking at all of it.
Thanks again.
Okay, I have read a great deal of your posts and I'm having trouble with the objective evidence that you said would be there. I gave you the benefit of a doubt but I'm pretty sure your perpetuating the same dogma as everyone else who chooses to believe the same thing you do. Is there any evidence that establishes the fact or does all your posts just reinterpret the evidence through the mechanisms of evolution. It would be extremely helpful if evolutionist would understand the term "objective evidence" because all I keep getting is your interpretation and nothing close to evidence that establishes your mechanisms as being functional. It just seems that since the evolutionist got their pants beat off of them thirty years ago in a field they monopolized for a time, they've had to resort to other ways of arguing. Now evolutionists do the elitist, "you're-an-idiot" approach and then say something that sounds intelligent that most people wouldn't know anything about and hope to fly by undetected. That approach seems to be working. It is taking a country by storm, yet it has not be proven with any sort of observable evidence. I can't say that enough. Being able to explain evolution and then interpret evidences in a different way does nothing to prove evidence or plausibility.
Is it possible that I have made my point yet or am I going to get more imagined drawings based on some guy's theory, perpetuated by his wasted education into super stardom? I looked at it all man. The theory can't even get off the ground if there are no transitional forms. To produce some seemingly transitional forms only shows me that you can theorize with very little evidence. The history that you claim is true would require so much more evidence that transitional forms should be the norm and we should have trouble finding the stuff we have now. If you disagree with that you are denying actual logic and stepping into the realms of religious faith.
Maybe you found what you wanted to find but dogma won't prove it.
Sam
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