Here’s biologist John Timmer to explain the orthodox Darwinian view of DNA from 2007:
Problem is, a study reported in Nature, one of the most highly respected scientific journals in the world, is that at least 80 percent of the human genome is active and the other 20 percent probably is to a very high proportion.Personally, I fall into the “it’s all junk” end of the spectrum. If almost all of these sequences are not conserved by evolution, and we haven’t found a function for any of them yet, it’s hard to see how the “none of it’s junk” view can be maintained. There’s also an absence of support for the intervening view, again because of a lack of evidence for actual utility. The genomes of closely related species have revealed very few genes added from non-coding DNA, and all of the structural RNA we’ve found has very specific sequence requirements. The all-junk view, in contrast, is consistent with current data.
One of the planks of the evolution platform is that
... because the genome of an organism has been cobbled together through a long, undirected evolutionary process, the genome is a patchwork of which only limited portions are essential to the organism. Thus on an evolutionary view we expect a lot of useless DNA.But there is very little "useless DNA." So to preserve this plank of evolution theory, biologists are going to have to figure how evolutionary processes managed both to preserve functional DNA while shedding "junk" DNA, and what were the gene-pool survival advantages of doing so.
Good luck with that.