It can shown that this is strong evidence for common descent by comparing the likelihood of the data among the various models. If one species arose by common descent from another containing the ERV, the likelihood of the ERV being in the same place in the genome is close to one (not exactly one because a deletion event is possible). What if the species were specially created? If the second species were specially created without the ERV, then the ERV would have to become inserted in a germline cell in the exact same spot, and then this would have to become fixated in the population. The likelihood is vanishingly small. What if the second species were specially created with the ERV? We will assume then that the ERV would have some function, that the likelihood that a designer would just stick some random “junk” in the DNA with no function or a deleterious function is zero or close to zero. Now in fact some ERVs do have a useful function, for instance one ERV is associated with placental formation (syncytin). Other ERVs have a deleterious effect, being associated with cancer for instance. But, in syncytin formation, the
entire ERV is not associated with syncytin. An ERV consists of three genes,
env,
gag, and
pol, as well as a long-term repeat (LTR). But only the
env gene is used for syncytin production. What’s the function of the rest of the ERV? Specifically, what’s the LTR (essentially “junk”), doing there? Why would a designer use specifically an ERV for this purpose? Why not just design an ordinary gene for syncytin?
Creationist responses in the past have typically included the following.
- Confusing the issue by citing ERVs not shared between primates, conveniently omitting the fact these are not in the same place in the genome, making the likelihood of independent insertions much greater.
- Confusing the issue by citing insertion hotspots; yes, insertion hotspots make certain regions more likely than others but insertion at the exact same location is still vanishingly unlikely in a genome with 3 billion base pairs.
- Confusing the issue by demanding an explanation for the differences in the genome, not just the similarities. This would be a valid point if the only options were “Biblical” creation versus atheistic, stochastic, undirected evolution. However they are not, and theories of front-loaded and/or directed evolution easily explain the similarities.
- Complaining that I am speculating on what a designer might or might not do. If a designer is brought into the equation, then it is necessary to do this in order to evaluate the evidence scientifically, which means evaluating likelihoods and applying Occam’s razor and parsimony. I can’t prove that angels don’t move the planets and stars around. But I can show their motion is accounted for by natural laws, which is a much more parsimonious explanation than angels, for the hypothesis space is much smaller. Why should angels be moving the planets in the exact same fashion as predicted by Kepler’s Laws, and later more accurately by general relativity? Similar considerations apply here.
Here is the AIG interpretation of retroviruses:
answersingenesis.org/articles/am/v1/n2/were-retroviruses-created-good which kind of just makes me want to say, get real.
Seeking Catholic,
Sorry to have taken so long to follow-up, the first time I even heard of these ERVs was right here, two days ago. I must say it was nice of you to provide a link to some of the alternative side’s information. I didn’t know about the AIG site either. I glanced at it and it appears to have a lot of interesting stuff.
I really don’t have a new argument, I actually think your case is good, as at least you make an argument which points to facts, explains their logical significance, anticipates challenges, etc. Your introduction is very well done.
It is interesting that you are making an argument for evolution, using probability, as of course this same argument is used (I think powerfully) from the other side. The only answer that evolutionists have to this I think is the hundreds of billions of years supposedly available.
This is a complex subject and I have not been able to more than scratch the surface. Of the common opposition (creationist) arguments you cite, I think your numbers 2 and 4 have validity. Number 2 (or a version of it) was actually suggested to me by my boss, an agnostic, oriental (raised Buddist, not practicing, and its not really “Theistic” anyway), well educated in all aspects of science. (We make a product that uses differential equations to model and optimize microbial metabolic rates given various environmental scenarios to solve for the optimal dissolved oxygen, the application is beleive it or not, wastewater processing). Anyway, we found ourselves waiting at a bank for service and I asked him what he knew about this issue. He said that it is not a meaningful case because many viruses seek and only operate in very specific locations. He pointed to a rash on his forehead, about an inch above his eye. He said this acts up when ever my resistance is down (he had just returned from a long trip to China) but it never spreads to my eye because that spot has different characteristics. He said even in the DNA chain, each location is unique and a virus may seek a preferred spot. Of course similar creatures may be vulnerable to the same virus. Since I beleive that all creatures are more or less specially created, it is possible that they all caught the same virus. Is it not? Of course re number 4), God could do what ever he wanted. We used to not know what the appendicts was for…we learn new things and old assumptions fail. BTW he is open to evolution but not convinced.