Confronted with the ENCODE results that attribute “function” to at least 80% of the genome, some Darwinist bloggers and critics of intelligent design have established a defensive perimeter around the precious idea of Junk DNA. It truly is that critically important to them. Their favored critique of ENCODE — call it the case for Junk DNA 2.0 — is that ENCODE’s definition of functionality is wrong. “Well, maybe it’s technically functional,” they say, “but it really isn’t.”
In logical terms, ENCODE reasons as follows:
(1) If X is biochemically active, then it has “function.”In other words, ENCODE defines function in terms of biochemical activity; assuming transcription into RNA is a biochemical function, then 80% of our DNA is functional. As the Washington Post put it, “‘Junk DNA’ Concept Debunked by New Analysis of Human Genome” (September 5). Exactly right.
(2) Noncoding regions a, b, c, and d are biochemically active.
(Conclusion) Therefore, regions a, b, c, and d have a “function.”
Of course, as the critics of ENCODE point out, it’s possible that not all biochemical activity is a sign of function in a living cell. But the critics’ unstated assumption seems to be:
(1a) If region or component X has a function, then it is biochemical.Now (1a) obviously doesn’t follow from anything in the first argument. To argue that it follows from (1) would be affirming the consequent, a first-order logic error. (1a) is logically independent of the first argument. The emphasis on biochemical function actually grows out of the Central Dogma (“DNA makes RNA makes protein makes us”), which in turn grows out of the neo-Darwinian need for DNA mutations to provide the raw materials for evolution.
Not only is (1a) independent of the logic of the ENCODE argument, but it is also false.
As Jonathan Wells documented in Chapter 7 of The Myth of Junk DNA, we already know of several non-biochemical functions of non-protein-coding DNA: providing a structural basis for centromeres (which in living cells are not just functional, but absolutely essential); providing spacers to regulate the timing of protein production; and focusing light in rod cells in the retinas of nocturnal mammals.
By analogy, iron has lots of functions. As ferric oxide, it can record digital information on a magnetic tape. As steel, it can support buildings and bridges. The latter is no less functional than the former.
So if anything, ENCODE uses too narrow a definition of function — by limiting it to “biochemical” function. For this reason, the functionality reported by ENCODE surely underestimates the total.
In the end, will our DNA turn out to be 80% functional, or 70% functional, or 90% functional? Committed anti-ID people like Larry Moran (University of Toronto) and Dennis Venema (BioLogos) will always define “function” to minimize the number. There’s not much point in squabbling with them about it. But whatever the number is now, we have every reason to expect the discovery of more and more genuine function in DNA, under any reasonable person’s definition.
The Darwinist bloggers are defending a ragged flag on a rapidly shrinking ice floe, insisting that the vast ocean around them is nothing to worry about. But if trends continue, as ENCODE gives us excellent reason to expect they will, then before long those defenders of junk DNA will be planting their flag in open water.
Happy sailing, gentlemen.