ERVs are probably the best argument that evolutionists have for universal common descent. After all, at least on the surface, it makes sense that the only way that different organisms could share the same viruses in the same location would be by common descent. However, a close look at this claim shows that it does not really work for several reasons. One of which is that it would make more sense if these genetic elements were non-functional, but not only are these segments of DNA functional, but they often perform important functions, including cellular immunity from viruses.
What are ERVs?
Endogenous retroviruses are viruses that infect the germ cells of an organism, such that they get passed on to its offspring, becoming a permanent part of its genome. This is the primary reason that evolutionist suggests that it is evidence of common descent. The idea is that if you find these viral sequences in the same place in the genomes of different species, then they could only have gotten there by common descent.
Viruses in general carry the genetic sequence that gets inserted into the genes of a host cell, where it hijacks the cell's machinery to reproduce itself. In the process, it will harm and even destroy the host cell. This is why getting a viral infection makes you sick. It is because your cellular machinery is being hijacked by an invader.
Assumptions of ERVs as evidence for common descent.
The idea that ERVs are evidence for common descent has three major assumptions. These assumptions are based primarily on naturalistic evolutionary Ideas about viruses and why they exist. If any one of these assumptions is wrong, it cannot be considered to be evidence for universal common descent.
They were inserted into the genome randomly. When Modern viruses insert themselves into a cell’s DNA, they do so randomly. The problem with this assumption is that it ignores the possibility of a loss of function over time. If Viruses originally had a function such as horizontal gene transfer, they may have had the ability to find specific places in the genome to insert themselves. The random aspect of them could have developed over time as they deteriorated from their original purpose.
They have no function for the organism. If the ERVs serve an important function within cells, then they are either original genetic material or a result of targeted Insertion for genetic transfer. The idea that ERVs are non-functioning viral insertions originates with the now disproven notion of junk DNA, where it was claimed that the overwhelming majority of our genetic material was non-functional junk. This is an idea that was totally disproven by the Encode Project. In fact, some ERVs have been demonstrated not only to have functions but also very important ones.
They were not original genomic elements. The other assumption is that ERVs are viral insertions, rather than original genetic material. This is strongly suggested by the observation that ERVs actually have functions. If indeed ERVs were original genetic material, we would expect them to be functional in some fashion.
Functional ERV’s contradicts common descent argument.
There are two main reasons why functional ERVs contradict the common dissent argument. After all, if they are viral insertions into the genome that get passed on to offspring, you would expect that in order for the offspring to survive, the virus would have to become non-functional. This fits perfectly with the evolutionary notion of junk DNA.
The first is that if they are functionally inserted DNA, then it is likely that the insertion is not random. In other words, a virus that is designed to add legitimate code to an organism's genome will likely be programmed to also seek a specific location. The result is that in any organisms with similar genomes, even unrelated ones, you would have a high probability and possibly even guarantee that such insertions will occur in the same place, particularly if that location is highly similar or even identical between the organisms.
The other reason why functional ERVs contradict the common dissent argument is that functionality suggests the likelihood that these genetic elements are original genomic content in a created organism. This would be enhanced if the function that they serve is critical to the survival of the cell.
The simple fact of the matter is that the Encode project has determined that the overwhelming majority of so-called ERVs have definite functions. Furthermore, these include all of the cases that we have in common with chimpanzees and other organisms. Furthermore, these tend to be fixed in their location within the genome, as opposed to others that move around, called transposons.
ERV-like sequences provide immunity against real viruses.
Many ERV-like genetic sequences perform a very important role in defending cells against viruses. When the cell is invaded by a viral RNA, these components are transcribed to produce an RNA molecule that can attach itself to the viral RNA, rendering it harmless. To perform this function, these genetic sequences need to look a lot like a viral sequence. This would be why they have viral-like patterns, while being functional, original DNA.
These ERV-like genetic sequences would not only be original material but also fixed within our genome. This would also explain why the same sequences are found in the same place in chimpanzees and similar animals. That is, such a location is necessary for it to do its job and has the result it is preprogrammed into the genome.
Transposons
Transposons are ERV-like genetic sequences that move around within our genome. Transposons (also called jumping genes) are DNA sequences that can move to new locations within a genome. Their movement can affect genes and genome structure in several important ways—some harmful, some neutral, and some beneficial. Transposons can copy and paste themselves to a new location (retrotransposons) or cut and paste themselves to a new location (DNA transposons). This mobility is their defining feature.
When a transposon inserts into or near a gene, it can affect genes in several ways. They can break a gene’s coding sequence, altering it often negatively. They can alter gene regulation by turning genes on or off. They can cause loss of function or abnormal expression. Such abnormal expressions are often harmful. Badly placed transposons are one way that mutations occur. Because unchecked movement can be damaging, cells silence transposons using DNA methylation, histone modification, and RNA
Some transposons carry promoters or enhancers, causing them to become part of regulatory networks. They help create new gene-expression patterns because many regulatory elements in genomes originated from transposons. This helps to increase genetic diversity and can even provide built-in potential diversity in a small population.
Possible origin for viruses.
One of the problems that evolutionists have concerning viruses is where they come from. This is because you have the problem that the virus needs to exist to infect the cell, but it needs cellular machinery to reproduce. So they have the uncertainty as to which came first, the virus or the cell. After all, viruses are a lot simpler than living cells.
Looking at the problem from a creationist perspective, there are two possible answers. The first is that God designed a horizontal gene transfer mechanism, following Adam's fall. This would have been targeted to where it implanted itself and would have been for the purpose of spreading around fall-related genetic sequences. This genetic targeting would have gotten lost as these sequences mutated over time.
The second would be whether they are transposons or fixed ERVs. Some of these virus-like elements escaped from their original cells as viruses. When they entered a new cell, they proved dangerous to the cell because it was not designed to handle them. The viral casings could have originally aided transposon mobility, including moving genetic material to other cells in the body as a way of repairing damage to those cells.
Conclusion.
The claim that ERVs are conclusive proof of common descent evolution is not only based on the assumption that the genetic elements in question are indeed ERVs, but that conclusion presupposes an evolutionary rather than a design perspective. In other words, considering these genetic elements to be ERVs makes sense from their model, and so they are confusing the interpretation with the evidence itself. This is a very common mistake made by evolutionists, and in fact, it is what they are doing most of the time when they claim that something is evidence for universal common descent evolution. They ignore the fact that you cannot disprove one model by assuming the interpretation of evidence from a competing model.
The fact that these ERV-like genetic elements have definite functions, including protecting the cell from viruses Is evidence against the common dissent interpretation. The fact that even transposons frequently serve regulatory functions within the genome, that is, turning on and off genes, adds to this.
Ultimately, the common descent model cannot really explain where these viruses originated from, while creationists have at least two different viable models, both of which could be correct.
