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Junk DNA

The discovery of DNA revolutionized biology.  There was a recent spate of articles talking about the significance of “junk” DNA.  You might be interested in hearing about it.

According to some scientists only about 20% of our DNA contains meaningful genetic information; the rest is “junk.”[1]  We know “junk” DNA exists, but don’t exactly know why.  Therefore many argue that the existence of this “junk” DNA proves the validity of random evolutionary theory.  The argument goes something as follows[2]:

  1. Random evolution is inherently a messy and inefficient process that doesn’t clean up after itself.  Therefore one would expect all the failures to leave trash around.
  2. There are vast differences in genome sizes.  We don’t know why, but it must be because evolution left more trash behind in some cases.
  3. The only way random evolution can work is with a preponderance of extraneous genes.  Otherwise mutational loads[3] (the degree to which a population’s fitness is altered through random evolutionary mutation) would prevent random evolutionary processes from working.

Actually, none of the above arguments proves the existence of random evolution beyond speculation.  Let’s examine each of those arguments:

  1. Intelligent design and execution is also a messy process.  Just consider our recent Mars rover, Curiosity, which left behind a wake of trash.  In fact, 99.7%[4] of that complete system was either consumed or discarded during the mission!  Yet it was the product of intelligent design.  Therefore the existence of “trash” does not demand or even imply the existence of “random” processes.
  2. Just because we don’t know why genome sizes are different does not demand or even imply the existence of “random” processes.  A well written software program is compact and effective.  A poorly written software program wanders all over the place, includes much extraneous information, is repetitious, yet achieves the same goal as the well written program.  Both are the products of intelligent design.  Therefore all one can say about the source of differing genome sizes at this moment is, “They are different, and we don’t know why.”
  3. This is a circular argument:  The only way our proposed solution (random evolution) can work is with the existence of a bunch of trash.  Therefore the existence of the trash confirms the truth of our proposed solution.  No way!  There may be other solutions that work equally well or better, and also explain the existence of the trash.

But more importantly, recent findings of the ENCODE project[5] seem to contradict the very existence of “junk” DNA itself by arguing that most of this “junk” DNA is actually performing essential functions.  The “junk” really isn’t “junk” after all!  It’s necessary to life, according to these findings.  The study likens this non-genetic (“junk”) DNA to regulator programs that control various DNA processes:

These regulator genes serve as control mechanisms, or switches, for the DNA. They can determine which genes turn on and off, or they can act as a kind of volume knob, turning a gene up or down depending on its specific function or epigenetic response (such as DNA methylation). These differences determine whether a gene sequence produces a strand of hair, or parts of a lung — or whether someone is susceptible to high blood pressure or cardiovascular disease.[6]

The prospects are exciting.  Correctly understanding the function of “junk” DNA may actually help us understand exactly how certain diseases start; perhaps even how we can prevent and cure them.  Incorrectly understanding them based on false assumptions leads nowhere.

As for the existence (or non-existence) of a designer:  “Junk” DNA proves nothing either way.  If it doesn’t exist, one can’t use its presumed existence to prove anything.  Even if it does exist, “trash” can be created as a result of random processes such as random evolution, or as a result of intelligent design and construction such as during a human building project.  Therefore we must seek other clues to discern the truth.  This article may prove enlightening.

A book has been recently published on the subject of junk DNA, “The Myth of Junk DNA” by Jonathan Wells.  Other references of potential interest regarding the issues addressed in this essay:


All is not as it looks.


[2] Surprisingly, there is comparatively little available literature supporting this thesis.  I selected the one which seemed most cogent and understandable.  There is much more literature arguing against this thesis.  http://blogs.scientificamerican.com/the-curious-wavefunction/2012/09/13/three-reasons-to-like-junk-dna/

[4] Rover alone: 899 kg; Spacecraft: 3893 kg; Complete system with launch vehicle: 284,450 kg

  1. joelghome
    September 17, 2012 at 8:42 pm

    Excellent brother! I would add that the fact that there is extra DNA parts, does not negate that the 20% we use is so complex and intricate, that it is STILL impossible for it to have happened by accident or random chance. Great entry!!

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