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Member (Idle past 4516 days) Posts: 250 From: Tasmania, Australia Joined: |
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Author | Topic: Adding information to the genome. | |||||||||||||||||||||||||||||||||||||||||||||||
Kaichos Man Member (Idle past 4516 days) Posts: 250 From: Tasmania, Australia Joined: |
Now, the -lactalbumin gene has substantial sequence similarity to a gene family that code for lysozymes (specifically to Ca2+ binding c-lysozymes). The material I found suggested the similarity was in the order of 35-40%. Hardly "substantial" when you consider human and mouse DNA is 92% similar. The calcium-binding lysozyme that's so strikingly similar to -lactalbumin isn't present in humans, is it? So it has to be a case of gene duplication followed by "whoops, we've lost one". All in all, not a great example of growing the genome through gene duplication. Edited by Kaichos Man, : No reason given. "Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy." Charles Darwin
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3 |
The material I found suggested the similarity was in the order of 35-40%. Hardly "substantial" when you consider human and mouse DNA is 92% similar. Either the source you read was wrong, or you misunderstood. 40% of the sequence is identical, the rest is very similar.
The calcium-binding lysozyme that's so strikingly similar to -lactalbumin isn't present in humans, is it? So it has to be a case of gene duplication followed by "whoops, we've lost one". I don't know for certain whether it's present in humans, but it is most certainly present in other mammals. It's possible we've subsequently lost it, but that is hardly relevant to the point, is it?
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3
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As an aside, on this:
Hardly "substantial" when you consider human and mouse DNA is 92% similar. Gene similarity is a concept that has many different ways of being understood. When scientists talk about similarity between individual genes they are usually talking about aligned sequence similarity - that is you place the two genomes and look for the base pairs that are identical and occur in the same order and count matches. Figures such as the 92% mouse DNA figure come from a completely different method which simply involves dropping DNA from both into solution and measuring temperature changes. These methods give completely different numbers. Then there's the relatedness figures given for siblings - 50% of your DNA with your brother, etc. - these are looking only at genes that vary between individuals in one of the possible populations. Different numbers again.
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Dr Adequate Member (Idle past 312 days) Posts: 16113 Joined: |
Doesn't it sound triumphant? Can't you see Charlie standing there, jut-jawed and resolute, beating back the hordes of bleating Creationists? Unfortunately, the paragraph finishes:
However, it is now clear that the mammary gland did not evolve from a brood pouch [1]. Laugh! Yes, after 150 years of research scientists know more about biology than Charles Darwin did. This is because scientists can find stuff out. They also think that creationists are a bunch of shambling halfwits, and that creationism is a load of driveling crap. This is because scientists can find stuff out.
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Briterican Member (Idle past 3977 days) Posts: 340 Joined: |
- deleted by Briterican -
Edited by Briterican, : Added nothing to the discussion. Please accept my self-censorship as an apology. Edited by Briterican, : No reason given.
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RAZD Member (Idle past 1433 days) Posts: 20714 From: the other end of the sidewalk Joined:
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Hi Modulus,
The origin and evolution of lactation, Anthony V Capuco and R Michael Akers Yep, I just googled it and found the source. They go on to discuss the evolutionary history of lactation and where it fits in the tree of descent from common ancestors:
quote: It's just classic creationists, quote mining from the introduction of a paper in which the authors attempt to define the problem that they wish to discuss. The structure of the paper is: Yes, the fact that original ideas may not be correct in details, and that later evidence and increased knowledge can result in revisions of such ideas is an integral basal concept in science that seems to escape some people. Enjoy. by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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Adminnemooseus Administrator Posts: 3976 Joined: |
The origin of mammary glands and lactation is certainly a new and interesting theme at this forum. How about having a subtitle that will show up in the topic message index (which Percy promises will return some day). Such may be useful in making this little gem stand out in the sea of the other messages.
Or something like that. No replies to this message. Adminnemooseus Edited by Adminnemooseus, : Change ID.
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Kaichos Man Member (Idle past 4516 days) Posts: 250 From: Tasmania, Australia Joined:
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Edited by Briterican, 23-Oct-2009 9:40 AM: Added nothing to the discussion. Please accept my self-censorship as an apology. Oh, don't be so self-deprecating, Briterican. Adding nothing to the discussion never stopped Doctor Adequate... "Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy." Charles Darwin
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Kaichos Man Member (Idle past 4516 days) Posts: 250 From: Tasmania, Australia Joined: |
It's possible we've subsequently lost it, but that is hardly relevant to the point, is it? It is when the point is adding information to the genome. Losing one gene and gaining another puts you back at even. Incidentally, some of the research suggested the a-lactalbumin gene evolved from Ca++ lysozyme, but most of it suggested they both evolved from a 'common ancestor' gene. Can you cast any light on this? "Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy." Charles Darwin
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Kaichos Man Member (Idle past 4516 days) Posts: 250 From: Tasmania, Australia Joined: |
Figures such as the 92% mouse DNA figure come from a completely different method which simply involves dropping DNA from both into solution and measuring temperature changes. These methods give completely different numbers.
You learn something new every day. While I don't doubt that what yousay is true, there are significant "ultraconserved" areas of identical sequence between humans and mice aren't there? (Not suggesting they are anything like the order of 92%, but it's interesting). "Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy." Charles Darwin
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Kaichos Man Member (Idle past 4516 days) Posts: 250 From: Tasmania, Australia Joined: |
Two hundred years after Darwin's birth, the theory of evolution by natural selection remains a cornerstone of biology, as it has withstood this and other challenges You, and Mr Jack, and RADZ, fail to see the point of the humour. It's not that Darwin got it wrong. It's that this scientist decided to make an editorial point about the theory and used, as it turned out, a very poor example to do so. I don't know if you're old enough to have been exposed to Monty Python, but it's in the same vein as: "They said I was mad to build a castle in a swamp, but I built it anyway- just to show them!...it sank into the swamp... "Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy." Charles Darwin
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3
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It's not that Darwin got it wrong. It's that this scientist decided to make an editorial point about the theory and used, as it turned out, a very poor example to do so. Um, no. Do you read many scientific papers, Kaichos Man? What you've identified as "an editorial point" is actually the part of the paper that might be characterised as the "literature review". It's normal practice in these to discuss the historical context of the research into which the paper fits. This often, maybe even usually, includes a quick overview of once popular ideas that turned out to be false.
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Kaichos Man Member (Idle past 4516 days) Posts: 250 From: Tasmania, Australia Joined:
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Lactation appears to be an ancient reproductive feature that pre-dates the origin of mammals. "Appears to be". Uh-huh.
A cogent theory for the evolution of the mammary gland and lactation has been provided Oh good. Cogent. We can relax.
The features of current mammals were gradually accrued through radiations of synapsid ancestors What, no "Once upon a time, long, long ago"?
and the mammary gland is hypothesized to have evolved from apocrine-like glands associated with hair follicles Oh dear, an hypothesis. Let's hope it's cogent.
Oftedal suggests that these glands evolved from providing primarily moisture and antimicrobials to parchment-shelled eggs Oh dear. He's got the proto-mammal suckling an egg on her hair follicle. Cogency alert!
Fossil evidence indicates that some of the therapsids and the mammalia-formes, which were present during the Triassic period more than 200 million years ago, produced a nutrient-rich milk-like secretion. Amazing! 200 million year old fossils, and not only can they tell that they secreted stuff, they even know what was in it!
later evidence and increased knowledge can result in revisions of such ideas Hmm. You know, I'm starting to like Darwin's version more and more...
Enjoy. I did. Immensely. "Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy." Charles Darwin
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Blue Jay Member (Idle past 2726 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined:
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Hi, Kaichos Man.
Kaichos Man writes: Losing one gene and gaining another puts you back at even. So, you agree that information can be added, as long as other information is taken away simultaneously? You do realize that this is still addition of information, right? And, you also realize that this requires every mutation that increases information to be accompanied by a simultaneous mutation that decreases information to the same or greater extent, right? The problem you'll run into here is that the occurrence of mutations is pretty much insensitive to the consequences of mutations. You're proposing some sort of pre-emptive, phenotypic feedback mechanism that regulates whether mutations occur based on what the results of their occurrence will be. I'm interested in hearing what you'll come up with for that. -Bluejay (a.k.a. Mantis, Thylacosmilus) Darwin loves you.
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Blzebub  Suspended Member (Idle past 5268 days) Posts: 129 Joined:
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You appear to be a worshipper of "the god of the gaps". Finding any gap in mankind's scientific knowledge, on any subject whatsoever, leads the gap-god-believer to declare that "god did it".
If we all behaved in this way, we'd all still be sitting in damp, cold caves.
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