This is about as vital and intimate a reminder as there could be that “junk” DNA isn’t the garbage that Darwinists once uniformly insisted it is.
The supposed junk is the 98 percent of human DNA that does not code for proteins, formerly dismissed as functionless debris left over from random, unguided evolutionary processes. Developing ovaries if you’re a female or testes if you’re a male turns out to be a valuable service of some non-coding DNA — in mice, but likely in men, and women, too.
This is from “Sex reversal following deletion of a single distal enhancer of Sox9,” by Nitzan Gonen et al. reporting in Science. The Francis Crick Institute, where Gonen is a postdoc, reports:
Male mice grow ovaries instead of testes if they are missing a small region of DNA that doesn’t contain any genes, finds a new paper published in Science.
The study, led by researchers at the Francis Crick Institute, could help explain disorders of sex development in humans, at least half of which have an unknown genetic cause.
Mammals will develop ovaries and become females unless the early sex organs have enough of a protein called SOX9 at a key stage in their development. SOX9 causes these organs to become testes, which then direct the rest of the embryo to become male.
The amount of SOX9 produced is controlled initially by the SRY protein encoded by the Sry gene, which is located on the Y chromosome. This is why males, who have an X chromosome and a Y chromosome, usually develop testes while females, who have two X chromosomes, do not.
Only 2% of human DNA contains the ‘code’ to produce proteins, key building blocks of life. The remaining 98% is ‘non-coding’ and was once thought to be unnecessary ‘junk’ DNA, but there is increasing evidence that it can play important roles.
The latest study adds to this evidence, showing that a small piece of DNA called enhancer 13 (Enh13), located over half a million bases away from the Sox9 gene, boosts SOX9 protein production at the right moment to trigger testes development. When the team genetically removed Enh13 from male (XY) mice, they developed ovaries and female genitalia. [Emphasis added.]
Dr. Gonen delivers another punch to the “junk” myth further down.
“Our study also highlights the important role of what some still refer to as ‘junk’ DNA, which makes up 98% of our genome. If a single enhancer can have this impact on sex determination, other non-coding regions might have similarly drastic effects.”
The “junk” view, once a prized piece of evidence for neo-Darwinian theory, is thus reduced to the province of the benighted, the reactionaries who “still refer to [it] as ‘junk’ DNA,” after science has already passed them by. Having volumes of garbage lying around was a logical prediction of Darwinism that is in the process of being falsified. Now, it seems likely that non-coding regions have not trivial but “drastic effects.”
This reversal helps explain why evolutionists like Richard Dawkins have radically revised a key claim. Dawkins himself, in the space of three years, went from assuring us that junk validates Darwinism to claiming that function is what it expects. What a theory! It can never, ever be wrong.
Photo credit: Greta Keenan, Francis Crick Institute, via EurekAlert!