Hey Discoveroids: Our DNA Is At Least 75% Junk

You’re familiar with the Discovery Institute’s argument against junk DNA. They insist that the genome is perfectly designed, without flaws, and every little scrap of it is designed to be functional. That’s because their transcendental designer — blessed be he! — wouldn’t do it any other way.

We found something at PhysOrg that is certain to infuriate the Discoveroids. The title is New limits to functional portion of human genome reported.

Gasp! How could there be limits to the portion that is functional? Surely the intelligent designer would make it all functional — wouldn’t he? We’re always delighted when there’s news that will upset creationists, so let’s see what this PhysOrg article is all about. Here are some excerpts, with bold font added by us for emphasis:

An evolutionary biologist at the University of Houston has published new calculations that indicate no more than 25 percent of the human genome is functional. That is in stark contrast to suggestions by scientists with the ENCODE project that as much as 80 percent of the genome is functional.

So at least 75 % is junk? The Discoveroids can’t ignore this. PhysOrg says:

In work published online inGenome Biology and Evolution, Dan Graur reports the functional portion of the human genome probably falls between 10 percent and 15 percent, with an upper limit of 25 percent. The rest is so-called junk DNA, or useless but harmless DNA.

Here’s the published paper: An upper limit on the functional fraction of the human genome, but you can’t read it without a subscription. Back to PhysOrg:

Graur, John and Rebecca Moores Professor of Biology and Biochemistry at UH [University of Houston], took a deceptively simple approach to determining how much of the genome is functional, using the deleterious mutation rate – that is, the rate at which harmful mutations occur – and the replacement fertility rate.

Both genome size and the rate of deleterious mutations in functional parts of the genome have previously been determined, and historical data documents human population levels. With that information, Graur developed a model to calculate the decrease in reproductive success induced by harmful mutations, known as the “mutational load,” in relation to the portion of the genome that is functional.

Interesting! PhysOrg tells us:

The functional portion of the genome is described as that which has a selected-effect function, that is, a function that arose through and is maintained by natural selection. … In his model, only functional portions of the genome can be damaged by deleterious mutations; mutations in nonfunctional portions are neutral since functionless parts can be neither damaged nor improved.

Okay. Let’s read on:

Because of deleterious mutations, each couple in each generation must produce slightly more children than two to maintain a constant population size. … If 80 percent of the genome were functional, unrealistically high birth rates would be required to sustain the population even if the deleterious mutation rate were at the low end of estimates, Graur found.

This is good! One last excerpt:

For 80 percent of the human genome to be functional, each couple in the world would have to beget on average 15 children and all but two would have to die or fail to reproduce,” he wrote. “If we use the upper bound for the deleterious mutation rate (2 × 10?8 mutations per nucleotide per generation), then … the number of children that each couple would have to have to maintain a constant population size would exceed the number of stars in the visible universe by ten orders of magnitude.”

The Discoveroids are going to have a problem with this, and they already had a problem with our DNA. While claiming that it’s a glorious code created by their wondrous designer, they can’t explain why any of it isn’t functional. Now, it appears that if it were all functional, our species couldn’t survive the inevitable mutations that the designer somehow allows to occur.

Copyright © 2017. The Sensuous Curmudgeon. All rights reserved.

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12 responses to “Hey Discoveroids: Our DNA Is At Least 75% Junk

  1. Excuse this non-scientist for intruding with this suggestion. How about, rather than a choice between yes-or-no, that there is a degree of function for each part of the genome? Some places which are critical, where even small changes are fatal, some places where even major differences make at most trivial differences, and a lot of places are in-between functional? Maybe all of the human is at least 1% functional?

    And I think that the junk DNA issue has been made too much of. A creationist always has the option of saying that we don’t know the ways of the Lord. He is capable of making us with non-functional DNA. Moreover, there may be features of our DNA that have a purpose other than genetic. We don’t have to get into fancy genomics to ask about functions: What is the function of our having different blood types, different finger-print patterns, different eye colors? Just as we don’t know the purpose of paleolithic cave art, we know that it is a product of intellligent human design.

  2. Ken Phelps

    “The Discoveroids are going to have a problem with this…”

    Does this not presuppose that they will feel the need to present a rational position? It seems more likely that they will follow their traditional role of saying some sciencey sounding words to placate and reassure the flock, all while studiously avoiding the actual scientific community and any need to make sense.

  3. The paper may be newly published but Graur has been talking about for some time. Sandwalk has a Youtube video of his that was put online in January: http://sandwalk.blogspot.kr/2017/02/dan-graur-explains-junk-dna.html

  4. Tom S,
    “rather than a choice between yes or no”. Interesting idea.
    For the vast majority of coding genes, absence or mutation creates big and often lethal problems (search “inborn errors in metabolism” for some examples). Very few are like the single point mutation in the gene for brown eye pigment which led to blue eyes. When compared between individuals, functional parts of DNA are essentially identical (any differences are trivial and code for the same amino acid or for an amino acid that does not alter protein function). Make a single change in a signaling or coding DNA segment which results altered proteins and you can detect significant changes in cell functioning and often the change is lethal.
    Alternatively, non-coding parts can be dramatically different between individuals or absent and the two individuals’ cells live and function the same. Non-coding segments also do not have the start and stop segments necessary for transcription and if they do somehow get transcribed, the resulting proteins are nonfunctional. For your idea, you would need a completely separate and as yet undiscovered mechanism of transcribing these junk segments and then some use for the nonfunctional proteins that resulted. Or some purpose for the segments such as telomeres perform. Either is a stretch.
    To me, the large number of people (mostly kids) needlessly suffering and dying from genetically based diseases is ample evidence that any designer(s) is either not very intelligent, or is an A-hole.

  5. Eric Lipps

    The DI’ers might handle this by simply saying that nonfunctional DNA is a product of mankind’s “sin nature” and proof that god is keeping us all alive by way of miracles since nature couldn’t possibly do it with so much of our genome useless.

  6. Of course biologists are well aware that some parts of the genome are more essential than others – mutations in some functional places will be fatal and mutations in other functional places will have a tiny negative effect. The beauty is that the equations for estimating genetic load automatically account for this. As the paper explains:
    “the mutational load does not depend on the strength of selection against any particular mutation. This surprising result comes from the fact that alleles under strong selection are relatively rare, but their effects on mean fitness are large, while the alleles under weak purifying selection are common, but their effects on mean fitness are small. As a result, the effects of these two types of mutation neatly cancel out. To understand the magnitude of the mutational load in a population, we need only determine the deleterious mutation rate, not the distribution of fitness effects.”

  7. @Eric Lipps:
    It is good luck that there are not more clever people supporting creationism.
    But if they were more clever, then they would not be supporting creationism.

  8. “limits to the portion that is functional”
    The Grand Old Designer (blessed be His/Her/Its Name) has limited Him/Her/Itself? Gasp indeed! Can’t be true. And it isn’t.

    “The Discoveroids can’t ignore this.”
    But they will try for a while.

    “If 80 percent of the genome were functional, unrealistically high birth rates would be required to sustain the population.”
    There you are! The Grand Old Designer of course realized this! Junk DNA does have a purpose: avoiding unrealistically high birth rates! See Gen. 3-16: “in sorrow thou shalt bring forth children!” But The Grand Old Designer (again blessed be His/Her/Its Name) in His/Her/Its Omnivolence wanted to avoid too much sorrow and hence created junk DNA. This actually confirms IDiocy! Isn’t it wonderful?

  9. Creationists are particularly apt to forgetting (if indeed they ever understood the fact) that natural selection acts on populations, not individuals. Or better: acts on the gene pool of a population, and that it is what is what confers benefits to the overall population over successive generations that is selected–even if the mechanism is sometimes imperfect in that deleterious effects can also thereby arise within some individuals within that population. The best example I know of is the mutation responsible in humans for sickle cell disease: IIRC, inheriting the mutation from one parent only confers some benefit in the form of resistance to malaria, but to pull it from both parents can lead to sickle cell disease (I’m sure I don’t have the details correct here, and would be happy to be corrected by those better qualified). I think (but am too lazy to check) that there are actually several similar mutations that arose independently in different regions–which seems far more likely the working of natural selection than the tinkering of an Apprentice Intelligent Designer.

  10. Megalonyx,
    Some of the other hemoglobin (Hgb) mutations include the alpha thalassemia, beta thalassemia, and Hgb C among others. Hgb C homozygotes confers complete immunity to some malaria strains, causes only mild anemia and none of the other disabling/lethal problems associated with Hgb S. Evolution predicts that Hgb C will replace Hgb S in malaria regions and this seems to be the trend. Still more evidence of evolution, not so smart designer(s), or that the smart designer(s) is an A–hole for making people suffer needlessly with Hgb S.

  11. @ Tom B: Many thanks for info, very interesting.

    Years ago, I had a Nigerian colleague in an office in London whose daughter suffered sickle cell disease; I could only dimly recall the technical details of the condition, though I will never forget the terrible emotional trauma to the family of losing a child. If it actually were an ‘intelligent’ but transcendent entity responsible for the condition, one would have to admit such an entity was indeed, as you put it, an ‘A-hole’

  12. It is interesting to contemplate the battle against malaria. As Behe points out in his “Edge of Evolution”, the best efforts of human intelligent design, are defeated by micro-evolution of the malaria parasite, while the micro-evolution of the human genome, such as have been mentioned here are still effective against malaria (although they may have serious faults).

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