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Why should he assume that all genetic variations represent "mutations?"
Absolutely not, in fact I get irritated with the word because I believe there are mechanisms that create new alleles (variations of the genes). I suspect it's some kind of an RNA strand or something but there is definitely something.
How do we know that any of these expressions were not found in Adam OR Eve or the sons of Noah or their wives? I am not sure how many genes you are talking about.
In the HAR (Human Accelerated Regions) they found 210 showing signs of major divergence. I really don't know how many brain related, protein coding and regulatory, genes would be involved but the simple answer is a lot.
In order to focus on human-specific changes that have functional importance, we first identified a set of genomic regions which are at least 100 bp in length and identical between chimp (P. troglodytes), mouse (Mus musculus), and rat (Rattus norvegicus) in at least 96% of alignment columns...Bioinformatic analysis of the 34,498 predicted functional elements shows that they are very similar to previously described highly conserved elements in the human genome. Only 19.6% overlap coding regions of human genes, while the remaining non-coding regions are mostly intergenic (45.4%) and intronic (31.0%)...
Forces Shaping the Fastest Evolving Regions in the Human Genome
Forces Shaping the Fastest Evolving Regions in the Human Genome
By way of analogy, you can get a camry with four cyl. or six. In the factory of meiosis, things are created that are not "mutations", but are a different options packages.
Right, the genes cross over from the diploid chromosomes, one set from each parent. Obviously, that's not a mutation, traits being inherited in this way can even adapt to new environments but mutations are not required. I know certain genes can be turned off and on, I'm not really sure how that works exactly but I know it happens.
Crossing-over also occurs during meiosis I. Crossing over is an exchange of genetic material by non-sister chromatids of a homologous pair of chromosomes. This exchange of genetic material is the basis for additional variation in the offspring (another being the recombination of genetic material from two different genetic sources, the parents). This can lead to better adaptations and hence is a part of the process of evolution. Meiosis
How do we know that the information that is optional did not reside in our ancestors and is not carried? That is a question, not a rhetorical question, since I don't know the answer.
A lot of times the scientists who research this sort of thing don't know. Here is an interesting example.
The finding grew out of a research project started three years ago in which Dr. Pruitt and Dr. Lolle were trying to understand the genes that control the plant's outer skin, or cuticle. As part of the project, they were studying plants with a mutated gene that made the plant's petals and other floral organs clump together. Because each of the plant's two copies of the gene were in mutated form, they had virtually no chance of having normal offspring.
But up to 10 percent of the plants' offspring kept reverting to normal. Various rare events can make this happen, but none involve altering the actual sequence of DNA units in the gene. Yet when the researchers analyzed the mutated gene, known as hothead, they found it had changed, with the mutated DNA units being changed back to normal form.
Startling Scientists, Plant Fixes Its Flawed Gene
But up to 10 percent of the plants' offspring kept reverting to normal. Various rare events can make this happen, but none involve altering the actual sequence of DNA units in the gene. Yet when the researchers analyzed the mutated gene, known as hothead, they found it had changed, with the mutated DNA units being changed back to normal form.
Startling Scientists, Plant Fixes Its Flawed Gene
And Mark, what is the latest on where such information would be stored. One thing that research seems to show is that our simplistic notion of what the genetic code is seems to have a less defined boundary that was taught 20 years ago. Does the fact that you don't see the information in the strands of the 46 base pairs mean that the information isn't otherwise there? Remember that geneticists must rely upon notions like "self organizing", which implies that the information is present somewhere that we have no idea about.
The article above suggest the RNA may have had a copy somewhere:
Dr. Pruitt said he favored the idea that there is an RNA backup copy for the entire genome, not just the hothead gene, and that it might be set in motion when the plant was under stress, as is the case with those having mutated hothead genes.
He and other experts said it was possible that an entire RNA backup copy of the genome could exist without being detected, especially since there has been no reason until now to look for it.
He and other experts said it was possible that an entire RNA backup copy of the genome could exist without being detected, especially since there has been no reason until now to look for it.
I kind of like this idea since they are finding out that the RNA is coming from all kinds of places that were previously thought to be junk DNA:

TANGLED GENES. In the classic view of the genome (top), individual genes were distinct segments of DNA that a cell transcribed into RNA whole and in one direction. New data show that multiple and overlapping genes can occupy a single strip of DNA that also produces several functional RNAs that don't encode proteins
The results from ENCODE were even more striking. In the slice of DNA studied in that project, between 74 percent and 93 percent of the genome produced RNA transcripts. What becomes of this tremendous output is uncertain. John M. Greally of the Albert Einstein College of Medicine in New York says it's likely that some portion of it is made accidentally and simply discarded. But the discovery that so much of the genome is being transcribed into RNA underscores how out-of-date the central dogma has become.
Mountains of new data are challenging old views
The results from ENCODE were even more striking. In the slice of DNA studied in that project, between 74 percent and 93 percent of the genome produced RNA transcripts. What becomes of this tremendous output is uncertain. John M. Greally of the Albert Einstein College of Medicine in New York says it's likely that some portion of it is made accidentally and simply discarded. But the discovery that so much of the genome is being transcribed into RNA underscores how out-of-date the central dogma has become.
Mountains of new data are challenging old views
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