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The Koala's Tale

For those who are unconvinced that endogenous retroviruses  derive from exogenous retroviruses. 
(Short jargon section at the bottom.)

Dr Jon Hanger with a friend.

Dr Jon Hanger worked as a vet at the Dreamworld theme park in Queensland Australia where a large number of koalas were dying of cancers. Retroviruses are often the cause of outbreaks of cancers like this.

Testing 200 captive and wild animals revealed that every one of them showed signs of a previously unknown retrovirus. It was named KoRV, standing for Koala RetroVirus.

KoRV DNA was then found in koala sperm. This meant that KoRV existed in both exogenous and endogenous forms. But certain isolated populations of koalas show no signs of KoRV and KoRV’s close similarity to gibbon ape leukemia virus (GALV) strongly suggests that the exogenous GALV jumped species to infect koalas. This means that endogenous KoRV was not originally “designed” into the koala’s DNA, but is an exogenous retrovirus that is in the process of becoming endogenized.

Moreover, endogenous KoRVs have been found in large numbers in multiple locations in the DNA of koalas.

Of 39 distinct KoRV proviral loci examined in a sire–dam–progeny triad, all proved to be vertically transmitted and endogenous; none was exogenous. Of the 39 endogenous KoRVs (enKoRVs), only one was present in the genomes of both the sire and the dam, suggesting that, at this early stage in the retroviral invasion of a host germ line, very large numbers of ERVs have proliferated at very low frequencies in the koala population. (Proliferation of Endogenous Retroviruses in the Early Stages of a Host Germ Line Invasion)

In other words, the progeny had inherited copies of KoRV in 39 different locations in its DNA. All of these corresponded to an ERV in one parent or the other, but only one of them was common to all three. The remaining 38 were in one parent, or the other, but not both. Proof that these were not “designed” into the koala genome, but acquired, either by direct endogenization, or by endogenization in an ancestor.

Other studies have found as much as 165 copies of KoRV per cell in some individuals. It appears that this retrovirus is capable of integrating into germ-line DNA in multiple locations, in large numbers.
  • Retrovirus - a virus that replicates by integrating a DNA version of its genome into the DNA of the cells of a host organism, inducing the host to make more viruses.
  • Exogenous retrovirus (or retroviral virion) - a (retro)viral particle capable of infecting cells.
  • Endogenous retrovirus (or ERV) - the DNA version of a retrovirus that has integrated into the DNA of a germ-line cell and has become heritable.
  • Endogenization - the process by which a virus becomes endogenous.


  1. But but, God designed the koala genome to do.Natural Genetic Engineering on itself! So the koala cells genetically engineered the endogenous retrovirus into themselves, and knew just where to insert them. And how could the genome be so amazing that it engineers itself? It must be intelligently designed!

    /down the rabbit hole

    1. :)


  2. I have to believe you're missing the point about ID. Let me give am analogy. Some one writes a very sophisticated software program, someone else writes a program to degrade it. The second program is able to use the original top producer copies of itself and distribute them to other machines and car them to repeat the cycle. This does not prove that the original program, let alone the computer running it, or the communication channels, came about by blind unguided chance. But that is exactly what you're claiming. Sorry, not buying it. Kerry Petersen

    1. I have removed your other comments, Kerry, because they were identical to this one. Endogenous retroviruses are clearly the inherited remains of retroviral integrations into germ-line DNA. Take a look at

  3. The problem, I think, is that you can't imagine a scenario where a Creator might create a virus that would be helpful in one context and harmful when removed from that context. It is easily within the ability of our Creator to do, and you have not demonstrated why He would never choose to do it. Death is by design of God. Disease is by design. Even if it were by chance, winning the debate helps nothing. Your argument is meaningless.

    1. If anything and everything is a "design of God", then that is an unfalsifiable hypothesis, and as such, is of no interest to science. Further, if God purposely introduced false and unnecessary evidence, appearing, to any honest and unprejudiced observer, to be solid evidence of common descent, then what you are saying is that this God is a liar and a deceiver. That strikes me as blasphemous.

    2. «Death is by design of God. Disease is by design.» That seems kind of blasphemous, too, at least for a creationist.

  4. Sure, there is the modern example of koala's being infected by an exogenous retrovirus that is integrating itself into the koala genome to become an endogenous retrovirus. How is this explained from an intelligent design perspective? Well, not everything that started off as designed maintains original functionality. Good designs decay over time if not maintained. Degenerative genetic changes can and do lead to parasitic activity in real time. The same thing can happen and obviously does happen with ERVs. These endogenous genetic elements that once functioned in a beneficial manner have, on occasion, become parasitic exogenous retroviruses. A famous example includes the HIV virus which is responsible for Acquired Immune Deficiency Syndrome or AIDS.

    On the other hand, however, how does this koala evidence of exogenous viral endogenization support the argument of common descent for all or even most ERVs sequences in all genomes? - like humans and apes? - especially the very large numbers of ERVs that are now known to be not only functionally beneficial, but vital?

    Consider again that so many ERVs are now being discovered to have functionality, tens of thousands of them, that it's hard to make ERVs out to be any more special or unique, over protein-coding genes, when it comes to their being markers of common descent vs. that of common design. After all, ERVs seem to regulate human transcription on such a large scale as to be one of the primary genetic factors governing the entire human genome.  In this light, it seems rather difficult to keep up the old argument that non-functional genetic sequences would never have been created by any reasonable designer in the same places within different creatures.  This argument loses a great deal of ground once non-coding genetic sequences, like ERVs, show themselves not only to be functionally beneficial, but vital to the functionality of complex genomes (like those of humans and apes).

    This is even more true once one considers the enormity of the odds against getting a random sequence of code to be randomly inserted into a genome and then to randomly evolve some beneficial much less vital highly complex function. The odds of such an event are enormously unlikely because of the rarity of such high-level functionalities within the vastness of sequence space at such levels of functional complexity.  The odds are so remote as to be essentially impossible, statistically, this side of trillions upon trillions upon trillions of years - a practical eternity of time. 

    Citing an example of ongoing endogenization of a viral sequences within the Koala gene pool, while interesting, is completely irrelevant to the main problems that confront the common descent hypothesis for ERVs within the human and ape genomes.  The odds are simply so far against this notion as to make it completely untenable outside of a children's fable or other forms of imagination or wishful thinking.  Certainly there is no testable science here...