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TeddyKGB said:It is, perhaps unsurprisingly, an RNA regulatory gene.
The researchers compared the genomes of humans, chimpanzees, mice and rats and identified sections of DNA that have remained largely unchanged over the 80 million years or so since we all shared a common ancestor.
TeddyKGB said:http://www.livescience.com/humanbiology/060816_har1_gene.html
It is, perhaps unsurprisingly, an RNA regulatory gene.
Mark Kennedy, the ball is firmly in your court.
Sorry. It was probably an unneccessarily provocative statement now that I think about it.mark kennedy said:First of all, if you are going to address me in an OP I would appreciate a PM letting me know about it.
And? Do you have a particular objection to the passage?Secondly, I think something in the way of an actual argument makes more sense then a link and a one line challenge. Let's see what you have:"Some DNA regions have hardly changed at all over many millions of years in most species," said study team member Katherine Pollard, who is now at the University of California, Davis. "My twist was to look for a subset of these genes that have changed just in humans."
Doesn't that kind of genetic divergence between humans and chimps, coupled with rapidly-mutating regions as mentioned in the OP, prove difficult for your assertions that there hasn't been enough time for that genetic distance to accumulate?According to most of the research I have been looking at the genetic basis for human evolution is elusive at best."It is logical to tackle the genetic aspects via both genome-wide analyses and candidate gene(Comparing the human and chimpanzee genomes: Searching for needles in a haystack http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16339373&dopt=Abstract)
studies. Genome-wide surveys could eliminate the majority of genomic sequence differences from consideration, while simultaneously identifying potential targets of opportunity. Meanwhile, candidate gene approaches can be based on such genomic surveys, on genes that may contribute to known differences in phenotypes or disease incidence/severity, or on mutations in the human population that impact unique aspects of the human condition."
I'm sure you already consider it insufficient before reading a single word.I'll take a look at the thread and see where the conversation went but that should be as much as the OP merits.
TeddyKGB said:Sorry. It was probably an unneccessarily provocative statement now that I think about it.
And? Do you have a particular objection to the passage?
Doesn't that kind of genetic divergence between humans and chimps, coupled with rapidly-mutating regions as mentioned in the OP, prove difficult for your assertions that there hasn't been enough time for that genetic distance to accumulate?
Actually, I'm not sure I know what your position is anymore.
I'm sure you already consider it insufficient before reading a single word.
JohnR7 said:They do not have a DNA sample from 80 million years ago.
So they do not know if the DNA has changed any in that amount of time or not.
It is pure speculation on their part, because they otherwise have no evidence.
I'm sorry, but who has ever claimed that?mark kennedy said:On the contray John, they have found excellent evidence that the human genome is unique. However, there is no evidence supporting that this gene could be altered so dramatically by mutational forces that are thought to have shaped it.
No one has ever argued that the human brain is anything other than a remarkable advantage.mark kennedy said:Your kidding I hope, these genes have experienced rapid evolution. Let's take a closer look:
"Topping off the list was HAR1, a section of DNA made up of 118 bases, or "letters." A computational analysis of HAR1 showed that is essentially the same in all mammals except humans."
Did you miss this, the human condition especially the human brain is unique. It is a promising article but I would really like to get some more specifics and I wanted to respond to this thread as soon as I found it.
One of the "simple answers" is selection pressure - natural, sexual, and otherwise. And frankly, I'm absolutely fed up with having to remind you every single time you enter a discussion that mutations themselves are only half the picture.Allow me to clarify, the human brain is three times the size of our closest relative. The genetic basis for this evolutionary leap remains elusive while the line of ancestory remains an unquestioned a priori fact in the minds of scientists. Do you think random mutations are some kind of an explanation because the researchers don't seem to think so.
"In the time since humans and chimps split about 6 million years ago, HAR1 has racked up 18 base substitutions when only one or none would be expected by chance.Simple answers for how these genes underwent such a dramatic transformation do not exist. Chance mutations will result in dangerous deleterious effects as I am sure we will find to be the case.
For comparison, the HAR1 region of chickens and chimps only differ by two substitutions, even though more than 310 million years have passed since they shared a common ancestor."
It's okay. You won't lose any imaginary points for being a late-comer.By the way, it's a fascinating article I just wish you had given me a heads up before posting the challenge.
sfs said:I'm afraid your response doesn't make a lot of sense to me. Why do you call this "new, more complex information"? The changes are simple substitutions of one nucleotide for another. What's more complex about replacing an A by a T, or a G by an A, something that happens randomly all the time? In your version of genetics, does DNA become even more complex if the T is later replaced by an A again, and you end up with the identical sequence you started with?
I also don't see why this would be difficult to accomplish with random mutations. Over the last seven million years, every nucleotide in the region (as with any region in the genome) has mutated a couple of hundred times in one of our ancestors. The raw material for selection, the "ERRORS" must have happened, so why shouldn't they have been selected for?
Yeah, it's called 'every species' genome is unique.'mark kennedy said:On the contray John, they have found excellent evidence that the human genome is unique.
What a priori limitation prevents "mutational forces" from doing so?However, there is no evidence supporting that this gene could be altered so dramatically by mutational forces that are thought to have shaped it.
TeddyKGB said:No one has ever argued that the human brain is anything other than a remarkable advantage.
The wholly unsupported undercurrent of your position seems to be that whatever makes humans unique must be special, unevolvable, and therefore designed.
One of the "simple answers" is selection pressure - natural, sexual, and otherwise. And frankly, I'm absolutely fed up with having to remind you every single time you enter a discussion that mutations themselves are only half the picture.
It's okay. You won't lose any imaginary points for being a late-comer.
TeddyKGB said:Yeah, it's called 'every species' genome is unique.'
What a priori limitation prevents "mutational forces" from doing so?
I consider it out of my hands at this point. And I will continue to do so until you come up with an objection more specific than "It didn't happen via evolution."mark kennedy said:Whatever makes us unique has to have a genetic basis for a mutational force capable of changing highly conserved genes like the HAR1 gene. Are you going to go into the particulars are talk in circles with generalities?
What? It's pretty underhanded to proclaim ignorance in the matter of selective advantages of a giant cerebral cortex.Natural selection can only act once there is an effect, you have failed to identify any viable cause.
Who said it was "off the charts"? A low probability series of mutations is hardly impossible, especially given the massive advantages in planning inherent to a well-developed frontal cortex.That tells us less then nothing of how 18 nucleotides were changed resulting in 6 amino acids involved in the development of the neocortex. Relaxed functional constraints is out the window since this is such a vital area. The only alternative is a selective advantage based on a statistical likelyhood that is off the charts. How many random mutations does it take to pull this off Teddy?
I refuse to take lessons in perspective from someone whose idea of a logical argument against human brain evolution is "Look how big it is!"mark kennedy said:Let me put this in perspective for you, the human brain is 6 times the size of mammals in general and 3 times that as the closest ape.
Do you have any idea how many conception events end in spontaneous abortion? Do you have any idea what causes the bulk of those?The very real deleterious affects of mutations on genes involved in the development of the human brain.
TeddyKGB said:I consider it out of my hands at this point. And I will continue to do so until you come up with an objection more specific than "It didn't happen via evolution."
What? It's pretty underhanded to proclaim ignorance in the matter of selective advantages of a giant cerebral cortex.
Who said it was "off the charts"? A low probability series of mutations is hardly impossible, especially given the massive advantages in planning inherent to a well-developed frontal cortex.
I sure hope you aren't trying to play like the quotes you have posted so far support your impossibility case.
TeddyKGB said:I refuse to take lessons in perspective from someone whose idea of a logical argument against human brain evolution is "Look how big it is!"
Do you have any idea how many conception events end in spontaneous abortion? Do you have any idea what causes the bulk of those?
Mutations can happen in any gene. They are highly random. The question is that once a mutation happens, does that mutation lead to a reproductive advantage for the resultant organism?mark kennedy said:TWhatever makes us unique has to have a genetic basis for a mutational force capable of changing highly conserved genes like the HAR1 gene. Are you going to go into the particulars are talk in circles with generalities?
They changed randomly, and each was separately selected for. Random mutations happen all the time, but the changes which decreased intelligence were selected out of the population, while the changes that increased intelligence were selected for, eventually spreading throughout the population.Natural selection can only act once there is an effect, you have failed to identify any viable cause. That tells us less then nothing of how 18 nucleotides were changed resulting in 6 amino acids involved in the development of the neocortex.
Chalnoth said:They changed randomly, and each was separately selected for. Random mutations happen all the time, but the changes which decreased intelligence were selected out of the population, while the changes that increased intelligence were selected for, eventually spreading throughout the population.
Quite simple: the evolutionary pressures were different. Obviously the selection pressures that the chimpanzees were under didn't favor the growing of larger brains. Thus any change to that chromosome that increased brain size wouldn't have been selected for, and wouldn't ever reach a significant portion of the population.mark kennedy said:Do you mean single nucleotides, small insertions and deletions, interspersed repeats or chromosomal rearrangements? Mind you we are talking about a gene that was highly conserved from 60 million years with only two nucleotides diverging between chickens and chimpanzees. When chimpanzees and humans are compared the HAR1 gene diverges by 18 nucleotides with 1 or 0 expected by chance. How do you explain this?
My answer is the same as it would be for any other trait: random mutation + differential reproductive success.mark kennedy said:You mean you simply don't have an answer for how the gene was altered. Now after challenging me with a news article you refuse to even discuss the abstract of the paper the article was based on.
This is just insulting. Show me where it has been published that the HAR1 gene changes can't be accounted for by existing mechanisms.Sure it is, once you actually have a better developed cerebral cortex. The problem is that there is no known genetic mechanism for altering the HAR1 gene on this level.
Is this some Behe-esque "the evolutionary explanation must explicitly account for the precise location and behavior of every molecule before I consider it valid" rhetoric? Because I'm tired of wasting my time on nonsense.You are starting with the effect which is the selective advantage you assumed a priori to have resulted. When I press you for the actual cause of the 18 nucleotide change you simply don't have an answer. Typical.
Show me where it says that the changes can't have happened via evolutionary mechanisms.You didn't read anything about this did you.
"Now, this is the fastest of the regions of rapid evolution in the non-protein-coding genome, according to the paper. But if there are any substantial number of these, the number of selected substitutions they involve could easily exceed the number of amino acid substitutions between the human and chimpanzee genomes (already more than 40,000). "
http://johnhawks.net/weblog/2006/08/16
I want you to say something other than a variation of "big brain = impossible to evolve."I sure hope you don't intend to ignore the fact that you challenged me personally and all the quotes and links are directly related to the discussion you proposed?
Do you want to discuss this research or just talk in circles around it?
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