New Scientist Challenges "Junk DNA"
Over the years, I've occasionally received e-mails from evolutionists citing an old study on mice where noncoding DNA was removed and supposedly the mice lived. The idea is that this shows how non-coding DNA is unnecessary "junk." However a new article in the journal New Scientist, "Mouse 'junk' DNA vital for gene regulation," suggests otherwise (as we noted earlier). Observes the New Scientist:
Some junk is worth keeping. Non-coding, or junk, mouse DNA contains vast amounts of information vital to gene function -- and those regulatory functions take up much more space on the genome than the all-important coding segments.The article cites a recent study in Nature which found some 300,000 functional regulatory elements from noncoding DNA in mice. But as reporter Hannah Krakauer explains, many of these coding elements are conserved in humans, implying function in the human genome as well:
The data could be useful for understanding human genetics as well. Using data from comparative genetic studies, the researchers found that the 300,000 functional elements make up about 70 per cent of the evolutionarily conserved non-coding DNA shared by mice and humans.Of course the rejoinder from the Darwin lobby is always, "Well, this only represents part of the genome, and there's much that still might be junk." The New Scientist article unwittingly provides an answer to that argument:
Even though the human genome was sequenced over a decade ago, gaps like these demonstrate just how little we know about what the large portions of those DNA sequences actually do.In fact, the Nature paper found that these 300,000 elements add up to some 11% of the mouse genome:
Here we apply the same experimental approach to a diverse set of 19 tissues and cell types in the mouse to produce a map of nearly 300,000 murine cis-regulatory sequences. The annotated sequences add up to 11% of the mouse genome, and include more than 70% of conserved non-coding sequences. ... These results indicate that a large fraction of cis-regulatory elements are active in a tissue-specific manner and are most probably involved in regulating tissue-specific gene expression.It's true that there's much of the genome we don't understand -- but why presume it must be junk? Certainly the trend line seems to predict that as we fill in more and more gaps in our knowledge, we'll keep finding functionally important DNA, not "junk."
(Yin Shen et al., "A map of the cis-regulatory sequences in the mouse genome," Nature (2012).)