A new finding about DNA differences in somatic cells overthrows a common assumption and might have dramatic implications for evolutionary studies.Okay, let's take a poll.
Young's Law (from Murphy's catalog of perverse tendencies in nature) states that all great discoveries are made by mistake. A corollary is that the greater the funding, the longer it takes to make the mistake, but we won't go there. Anyway, a team of Yale scientists wasn't looking to overturn a huge assumption in genetics -- but they did. The ripple effects of their discovery remain to be seen.
We've all been told that every cell in our body has a copy of our unique genetic code. That's one of those simplistic beliefs that sounds sensible but is almost impossible to check. Doesn't the whole body arise from cell divisions of a single zygote with its unique genetic code? Yes, but it doesn't necessarily follow that the genes in cells downstream don't get modified. That was just assumed....
"Somatic mosaicism" is jargon for the finding that genomes differ from cell to cell -- not only in copy number variations (CNV's), but in single nucleotide polymorphisms (SNP's). The assumption that you have one genome is thus falsified. You have lots of genomes!
How many of you thought that mutations such as nucleotide substitutions, deletions, and insertions, could never take place during the thousands of generations that give rise to our somatic cells? (How were they supposed to be suppressed?)
How many of you thought that all of our cells, including red blood cells, contain copies of our unmodified genome?
How many of you thought that there were no polyploid cells in our liver?
How many of you thought that B cells, and T cells (and others) contain the same identical copy of our genome that's found in germ cells?
How many of you thought that spermatocytes and ovaries have exactly the same genome as our original zygote?
How many of you thought that cancer-causing gene rearrangements and mutations in somatic cells were impossible?
How many of you are completely ignorant of any medical problems due to genetic mosaicism?
If you answered "yes" to all of those questions then, congratulations!, you're as smart as an IDiot.
Sheeesh!
One thing is clear at this stage: the assumption that each individual has a unique genome has been overthrown to some extent. Think how this might impact common evolutionary studies. For years, evolutionists have claimed small differences between human and chimpanzee genomes. What if the percent difference is a function of the source cells used? Remember, the Yale team found differences between cells in the same organ -- human skin. If the percent difference grows or shrinks depending on the source, any conclusions about human-chimp similarities would prove unreliable.
Just one question for this anonymous commenter (and I'll bet he's glad he chose to stay anonymous!): is this remarkable discovery you're alluding to something that was made in, like, the 1920s? Because I'm pretty sure we knew about karyotype variation in the 1920s.
ReplyDeleteI had learned about this research finding a few days ago, I think from Science News. I know that abundant copy number variations had been known to exist between individuals, and so it is not really surprising that they occur within an individual.
ReplyDeleteAnyway, IDiots will be IDiotic. The differences between humans and chimps are not b/c of these sorts of differences, but are instead due to differences in exons and gene regulatory regions. Duh.
It seems that the IDiot also doesn't understand the difference between DNA and genetic code.
ReplyDeleteSadly, it's not just the IDiots.
ReplyDeleteI just reviewed a paper where the authors kept saying "genetically identical mice" when they meant "mice from the same genetic background" or "from the same inbred strain". I pointed this out in two rounds of review, but the authors did not want to change it, and the editors did not take this point seriously. This error will probably be there in the upcoming Cell paper.
How many of you thought that there were no polyploid cells in our liver?
ReplyDeleteWell, live and learn - I never knew that! This sounds suspiciously like a design defect. Particularly as applied to the organ that's designed to regenerate easily.
How many of you thought that identical twins were literally identical?
ReplyDelete...only people who've never done the math of multiplying mutation rate/bp x # bp in the genome.
Delete;-)
You may want to add:
ReplyDeleteHow many of you have never heard of loss of heterozygosity?
How many of you are unaware of gene amplification in amphibia?
How many of you are unaware of sister chromatid exchange?
ReplyDeleteWait, is this IDiot proposing that every cell with a SNP should be thought of as an entirely new genome?
ReplyDeleteOf course, you silly atheist. It only takes one (1) mutation to make the genome "diferent", isn't it? Tss tss.
DeleteDoes that mean that each different genome has a "soul" ?
DeleteWhat if the percent difference is a function of the source cells used?
ReplyDeleteSince the difference would only increase from the zygotic stage on, wouldn't that mean that we have overestimated the human-chimp difference? And that our genomes are actually MORE similar? I would think that ID creationists would try to argue the other way.
The ID drivel shows that their crowd doesn't even understand how to appropriate the study for their own profit. A clear example of saying anything, just in case, and with no regard about how idiotic they make themselves look. Anyway, the critique is to the point, and if weren't for science's duty to fight ignorance, the ID post wouldn't deserve any attention.
ReplyDeleteAnyway, the Yale study only adds to the understanding we already had on the topic. Perhaps even some more detail to the picture... which is always welcomed. The clowns, like Paul calls them, cannot even provide entertainment...
Truly incredible. So, will this bit of ignorance be scrubbed, or will they double down?
ReplyDeleteIf the percent difference grows or shrinks depending on the source, any conclusions about human-chimp similarities would prove unreliable.
ReplyDeleteAre they unaware that what their comment and proper understanding of genome variation within somatic cells would imply that we are even more similar to chimps than commonly reported?
The funniest thing about the rational the IDiots extract from the paper is that it is usually them who claim that genomes can not change because this would require some intelligent intervention. Since they can not totally ignore mutations they usually sum them up as genetic entropy that would lead to the death of affected cells or organisms. In the current case they of course ignore the fact that albeit neighbouring cells contain different sequences the organism obviously is doing well because these facts can only be explained if junk DNA exists.
ReplyDeleteGood point, the alternative for them is to accept that all their imagined to be functional DNA of any organism can actually mutate to a substantial degree and still produce a viable organism, which seems to contradict when they insist there's only a few specific functional sequences in a gigantic desert of nonfunctionality.
Delete"Think how this might impact common evolutionary studies. For years, evolutionists have claimed small differences between human and chimpanzee genomes. What if the percent difference is a function of the source cells used? "
ReplyDeleteI find it really cute how enthusiastically this was written. You can feel their excitement, thinking they're really onto something!
What if the percent difference is a function of the source cells used?
DeleteSo do the work and demonstrate whether or not the apparent species distance varies with genetic distance from the zygote? Or look it up. Fame and fortune await if you can debunk relatedness that way.
ENV might also want to get onto the respective Genome Project people and tell them their genomes are really tissue type genomes - and probably just from individuals - and not representative of the species at fresh zygote level. They were probably wondering.
They also have another piece of News and Views, entitled "How Would We Know if We Were Getting Stupider?" A good question. It seems they've been getting stupider for some time and don't know it.
ReplyDelete
ReplyDeleteThis is actual part and parcel thinking on the American Right, and a crucial component of the conservative bubble. Here's how it works:
1) A study appears making a claim that runs counter to your ideology (ie women are still discriminated against and paid less than men)
2) Come up with a possible (and usually embarassingly basic) error in methodology (ie the study did not control for different professions)
3) Reject the study as liberally biased, without bothering to verify that they study contained the hypothesized flaw.
They just applied it to gene comparisons. Never mind verifying that the source of the genes was different, just hypothesize that it was and reject the conclusions, thus keeping your ideology in tact.
LOL! Very funny posting. Keep 'em coming. I am teaching a formal course in Evolution for the first time this fall -- and need comic relief to combat rampant IDioSEE.
ReplyDeleteWell, there are IDiots but only one Moron.
ReplyDelete