Tuesday, April 10, 2007
Evidence for Evolution
Here's another one of those videos that are supposed to prove evolution. Before you watch it, let me give you the counter-argument. The amino acid glutamate is encoded by two different codons GAA and GAG. There is no bias in favor of one or the other so evolution would predict that the codons for glutamate can freely mutate from GAA to GAG or from GAG to GAA. If we examine several different species then we expect to see differences in the glutamate codons according to the neutral theory of evolution.
However, when we look at all the glutamate codons from α- and β-globin genes in humans, chimps, and monkeys we see that all the codons are identical. There has not been one single change as predicted by evolution. The chance of this happening if evolution is correct is 16 million to one. Thus, these genes must have been designed by an intelligent being who choose to use the same DNA sequence for all primates.
I don't like Intelligent Design Creationism. It's bad science. However, we aren't going to win any arguments by using silly examples that can easily be refuted by anyone with a brain. Is this is an example of the sort of framing that we're supposed to be practicing?
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13 comments :
Well, I wouldn't say that the example ID argument that you offered has "refuted" the video. That is too strong of a word.
Do we know what assumptions underly the 16 million to one probability?
I suspect they got sixteen million by multiplying the 2 options repeatedly -- 2 * 2 * 2 etc. -- for each position.
The video's argument is a little obscure, but I think they are trying to say that there is no design reason to choose one codon over the other, therefore they should be randomly distributed, but we observe the same codon because of common ancestry. I agree it is not a scintillating argument.
They would be better off looking at hundreds of characters and dozens of species, instead of this very small subset of data, where it is not at all clear what you "should" expect.
Hmm, I thought that the video was pretty good for what it purports to be, "one simple piece of evidence".
I'm really surprised at Larry's 'ID rebuttle'; or did he mean it to be really dumb? It goes from "If we examine several different species then we expect to see differences in the glutamate codons according to the neutral theory of evolution." directly to "However, when we look at all the glutamate codons from α- and β-globin genes in humans, chimps, and monkeys we see that all the codons are identical." as if 'the neutral theory of evolution' predicts that we should see changes under these circumstances (relatively recent divergence, mutation rate, neutral fixation rate). Now, not having done the calculations, I don't know what the correct prediction is but I doubt it is anywhere near a 1:16 million difference from what is seen (identical). And the probability quoted has no connection to the evolutionary expectations but is, as the video says, "the probability of that occurring by chance" ("that" being 12 ordered matches in the codons).
They also note that they are looking at only 2 of 30,000 (just a little high in the estimate :)) genes and using only 3 species.The clear implication is that analysing more genes in more species would offer more support.
- But what if neutral theory is wrong? ;-)
Hmm. I've seen some of the videos in that series before, and they seem pretty efficient too me. (Albeit with the usual few nitpicks on erroneous details.)
The argument is self-contained. Since its version of ID doesn't give any specific predictions (true), and it matches recent divergence (which I assume is true), evolution wins the day.
To borrow Nick's words, Larry's objections are somewhat obscure to me.
If the objection is that ID can postdict any observation, sure - it follows from not doing predictions. The IDiot will do that to deflect a 'frame shift', and refuse to acknowledge or being ignorant of the problem with that. This happens when facing all kinds of evidence, and there is absolutely nothing we can do about that.
But the video could be efficient with rational fence-sitters. Myself, I found it describing an interesting fact I didn't know.
If the objection is that it isn't informative with evolution and especially neutral theory, not discussing the time frame for divergence, et cetera, I'm not sure that it matters much. It is the framing that matters, not the boring details, right? :-)
Btw, that is how I see the 30 k genome number. As a physicist it is an approximation that seems fair in the context. I could nitpick on the malpractice of giving it too high precision, but then again it is supposed to be a fast readable datum, so I would cut the video some slack.
Torbjörn Larsson says,
To borrow Nick's words, Larry's objections are somewhat obscure to me.
Then let me make it more clear. According to the video, evolution predicts no change in the DNA sequence of the globin genes. Looking at the data we see no change. Ergo, evolution is true and Intelligent Design Creationism is false.
If one of my students submitted an argument like that in an essay, they'd get a failing mark. I'm very surprised that some people think the video argument is an effective way to support evolution.
If evolutionists want to end the arguments all they have to do is, get their brilliant heads together and assemble a 'simple' living cell. This should be possible, since they certainly have a very great amount of knowledge about what is inside the 'simple' cell.
After all, shouldn't all the combined Intelligence of all the worlds scientist be able the do what chance encounters with random chemicals, without a set of instructions, accomplished about 4 billion years ago,according to the evolutionists, having no intelligence at all available to help them along in their quest to become a living entity. Surely then the evolutionists scientists today should be able to make us a 'simple' cell.
If it weren't so pitiful it would be humorous, that intelligent people have swallowed the evolution mythology.
Beyond doubt, the main reason people believe in evolution is that sources they admire, say it is so. It would pay for these people to do a thorough examination of all the evidence CONTRARY to evolution that is readily available: Try answersingenesis.org. The evolutionists should honestly examine the SUPPOSED evidence 'FOR' evolution for THEMSELVES.
Build us a cell, from scratch, with the required raw material, that is with NO cell material, just the 'raw' stuff, and the argument is over. But if the scientists are unsuccessful, perhaps they should try Mother Earth's recipe, you know, the one they claim worked the first time about 4 billion years ago, so they say. All they need to do is to gather all the chemicals that we know are essential for life, pour them into a large clay pot and stir vigorously for a few billion years, and Walla, LIFE!
Oh, you don't believe the 'original' Mother Earth recipe will work? You are NOT alone, Neither do I, and MILLIONS of others!
Build us a cell, from scratch, with the required raw material, that is with NO cell material, just the 'raw' stuff, and the argument is over.
This will surely become feasible someday (assuming anybody wants to fund such a huge but pointless technological effort), the main barriers even now being merely the sheer number of different chemical components in even the simplest prokaryotic cell (and the fact that not all aspects of their spatial organization are fully understood yet), and the fact that technology for chemical synthesis of proteins lags way behind that for nucleic acids (and since there's little real-world demand for it, there's little incentive to develop the technology.) So then, what will your next excuse be after it's accomplished? (Here's a nontechnical newspaper account of some steps along the way: http://tinyurl.com/ynp7n5)
By the way, are you a vitalist? Do you think being living involves some kind of mysterious "essnece" above and beyond chemistry and physics?
Larry Moran said:
According to the video, evolution predicts no change in the DNA sequence of the globin genes. Looking at the data we see no change. Ergo, evolution is true and Intelligent Design Creationism is false.
If one of my students submitted an argument like that in an essay, they'd get a failing mark.
It seems to me that you are reading much more into the video than is there. Everything up to "Ergo" in your reply is fine, but after that it is your own 'spin'. They obviously believe that "evolution is true and Intelligent Design Creationism is false" but all they say in the video that what they present is a small piece of evidence in support of the theory of evolution and that 'Intelligent Design Creationism' makes no predictions in this case (ie isn't science/scientific). Is there a reason to think that this isn't a small piece of evidence in support of the theory of evolution?
As far as getting a failing grade as an essay, well, it isn't an essay. Particularly not one from a student to a professor. It's a short presentation of the type of data/analysis that provides support to the ToE aimed at the layman. As such, I think it's pretty good and don't see why you are coming down on it so hard.
“According to the video, evolution predicts no change in the DNA sequence of the globin genes. Looking at the data we see no change. Ergo, evolution is true and Intelligent Design Creationism is false”
But to be fair, that’s not what the video said. The video actually said:
“since mutations occur at a low rate, closely related species should use the same codons for glutamic acid simply because there has not been enough time for divergence” (my emphasis).
Now I’m with Nick on this one, ie the authors of the video could have presented their argument better. So for example, having pointed out the fact that primates use the same glutamate codons, they could also have shown the codon usage for these positions in more distantly related organisms. It turns out for example that in birds one of these codons in the alpha globin gene is GAA not GAG and so on. Then they could have mapped these identities and differences onto a standard phylogenetic tree to show how both the identities and differences form a pattern - a pattern best explained by the theory of evolution.
Anonymous sez:
"Walla!"
GAG me.
"Intelligent Design Creationism is false."
OK, now I understand. But I don't think they claimed that, but they claimed that ID isn't predictive. I took it to mean ID shouldn't be considered.
The counter-counter-argument to the one Larry posited is rooted in Larry's statement, "There is no bias in favor of one or the other [glutamate codons]", which is 100% false. I'm stunned that no other commenters caught this. As the authors of the video stated, "codon bias can affect the rate of translation". I think the specific objection Larry has to the video is that it doesn't do anything to explain what this bias (or biases, really) might be and exactly how it may slow down translation, and why this is significant, thus dumbing down the argument nearly to the point of uselessness. This point about bias was just one small one, Larry could have attacked any of dozens of glossed over, major concepts in the video.
That's really all I should say on that, but since I did mention that there is more to the bias story, I'll just finish that part and be on my way. A table showing the frequency with which codons are used in humans can be found here: http://www.kazusa.or.jp/codon/cgi-bin/showcodon.cgi?species=Homo+sapiens+[gbpri]
As you'll notice, the most common Glu codon is GAG, and according to the video it seems that all but two of the Glu codons are GAG. In most organisms (all?) these codon frequencies correspond very closely to relative abundance of tRNAs which are responsible for converting a given codon into an amino acid.
We need a crapload of hemoglobin and so this particular protein needs to be made extremely quickly, so it makes some sense that most of the Glu codons are "GAG", but if that is the case, why aren't all of them GAG? Why are there two "GAA" codons? Well the short answer is, I don't know, but if you will allow me to speculate, there is precedence for non-optimal codon use in proteins where a "pause" in translation is required for one reason or another (usually to permit proper protein folding, but also sometimes to cleave away some kind of leader peptide, or to enhance the kinetics of some other sort of post-translational modification. Of course the ratio between the use of GAA and GAG is fairly close (as compared to say, Glutamine) so my speculation above may be no more than just that, speculation. Changes between Glu codons probably will not slow down translation enough to be noticeable deleterious and the reason why those two "GAA" codons exist could be nothing more than a conserved random mutation somewhere in our tree which was did not impact our fitness enough to eradicate itself.
So, as Larry correctly pointed out, the argument presented in this video to support evolution is at best incomplete, and at worst, misleading. Thus his reference to this whole "framing" debate going on. We scientists do not want the public to simply trust our authority, we'd rather they be smart enough to weigh the evidence we can provide. This means that the public has to be willing to do the hard work of actually understanding the evidence we uncover. This dumbed-down spoon-feeding has to stop. Americans are smarter than they present themselves. And if they really truly aren't, don't blame the scientists for not trying to make people understand, we can only teach unwilling students so much.
Larry, am I in the ballpark here? I think alot of people missed the point you were going after.
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