Convergent Evolution of Introns Challenges Common Descent and Random Mutation - Evolution News & Views

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Convergent Evolution of Introns Challenges Common Descent and Random Mutation

A recent article in ScienceDaily titled " Introns Nonsense DNA May Be More Important to Evolution of Genomes Than Thought," actually demonstrates nothing like Darwinian evolution. Introns are stretches of DNA within genes in Eukaryotes that do not code for proteins. But they aren't functionless and can play important roles in splicing together proteins. According to the ScienceDaily article:

"The scientists also found what appear to be "hot spots" for intron insertion -- areas of the genome where repeated insertions are more likely to occur.
This implies the occurrence of convergent genetic evolution of introns at specific locations, or as the article repeatedly puts it, "parallel intron gains." The study's principal investigator, Michael Lynch, was clear about the implications:
Michael Lynch, the project's principal investigator, agreed that the discovery of parallelism will surprise his colleagues.

"Remarkably, we have found many cases of parallel intron gains at essentially the same sites in independent genotypes," Lynch said. "This strongly argues against the common assumption that when two species share introns at the same site, it is always due to inheritance from a common ancestor."

So there's an admission that genetic similarity, i.e. the presence or absence of an intron at a particular locus within a gene, no longer necessarily implies inheritance from a common ancestor. This challenges a key component of the methodology commonly used to infer common descent.

But the implications of this sort of data go even deeper: According to the ScienceDaily article, "surprisingly, the vast majority of intron DNA sequences the scientists examined were of unknown origin." That means they couldn't find homology for those intronic DNA sequences with any other known stretch of DNA. So what possible mechanism could spontaneously produce functional genetic strings de novo inserted into identical locations in parallel lineages? Consider this comment:

"The thinking has been that these insertion events are very rare because they always have bad effects," said postdoctoral fellow Abraham Tucker, a lead author of the Science paper.
The reason they believed such events would be rare is simple: randomly inserting a bunch of novel DNA into a gene is highly likely to destroy the gene. Hence the argument has always been--so long as we're operating under Darwinian assumptions--that most intronic insertions will be junk. After all, what natural mechanism could blindly insert a bunch of nucleotides into a gene without destroying it?

But what if Darwinian assumptions are wrong? There is a mechanism that can produce non-deleterious functional genetic information--but it isn't random mutation. What they call "hotspot mutations" may just be another word for "non-random insertion of DNA."

What is the natural mechanism for creating functional, non-random DNA de novo? "Hotspot mutation" is a word for an observed effect--the presence of genetic modules in identical locations in parallel lineages where the common ancestor did not have that DNA--not an explanatory cause.

This sort of convergent genetic evolution not only pulls the rug out from the under part of the methodology used to infer common descent, but it strains the credulity of the Darwinian mechanism to insert functional genetic modules into the same location independently in separate lineages. It begs for an explanatory cause that can produce functional information. The only known cause which produces new functional genetic information (intelligent design), for now, must go unspoken.


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