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.
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