Creationism in Crisis - How An Ancient Retrovirus Evolved To Create The Vertebrate Brain

A myelinating oligodendrocyte (green)

Credit: Peggy Assinck,
ALTOS Labs-Cambridge Institute Of Science

Ancient retroviruses played a key role in the evolution of vertebrate brains | ScienceDaily

Schematic diagram of a neuron show the myelin sheath as the electrical insulator of the axon.

Wikimedia Commons (CC BY-SA 3.0)

Extinct Late Devonian placoderm Bothriolepis canadensis. Myelin first appeared in these primitive early fish

Credit: Nobumichi Tamura / Stocktrek Images / Getty.

Creationists generally hate endogenous retrovirus (ERV's) because:

1. They are one of the strongest pieces of evidence of common descent appearing in the same locations in the genome of all organisms in a clade, forming nested hierarchies exactly as the Theory of Evolution predicts. The probability of the same viral DNA appearing in the same locus in all species in a clade by chance is, of course, so small it can be dismissed as an explanation.
2. They form a large part of the 'junk' DNA carried by all organisms, which, although a small proportion of it is transcribed into RNA, the RNA doesn't get translated into proteins and most of it doesn't serve any purpose. Some, but by no means all of it may have some regulatory functions.
3. Occasionally, an ancient ERV may have become exapted for some useful purpose unrelated to the original virus, so showing how new genetic information can enter a genome, flatly contradicting creationist's claims that no new information can arise within a genome because the second law of thermodynamics [sic] and Shannon Information Theory somehow forbids it.
4. An ERV serving a useful purpose also contradicts creationist claims that, while their favourite creator god is responsible for all the good stuff, another creator, called 'Sin', is responsible for the harmful stuff like parasites and viruses. Yet in those exapted ERVs we have viruses providing something that is beneficial and therefore, according to creationist dogma, must have been provided by their god!
5. Lastly, the examples of where ancient ERVs have mutated and provided some additional ability or function, such as enabling the formation of the myeline sheath in vertebrates, can't be regarded as detrimental mutations, yet creationist dogma, courtesy of the hapless Micheal J. Behe, is that all mutations are 'devolutionary'[sic].

Creationism in Crisis - A New Endogenous Retrovirus Caught In The Act Of Invading a Genome

white-bellied mosaic-tailed rat Melomys leucogaster.
The species is being infected with the gibbon leukemia retrovirus.

Photo by Carlos Bocos

A rare recent case of retrovirus integration: An infectious gibbon ape leukemia virus is colonising a rodent’s genome in New Guinea - Leibniz Institute for Zoo and Wildlife Research

Researchers have discovered that a retrovirus is currently in the process of invading the genome of a rodent in New Guinea. This will add to the extensive list of known endogenous retroviruses. The virus, which appear to be harmless to the rodent - a mosaic tailed rat of the Melomys genus - is an infectious virus that causes leukemia in gibbons.

A retrovirus is an RNA virus that 'hides' in its host's DNA by inserting the DNA template for its RNA, using the enzyme reverse transcriptase that is coded for in its RNA. Once inserted it is replicated by every daughter cell. If it is inserted into the DNA of a germline cell, it can be passed on to the next generation.

Endogenous retroviruses (ERVs) are common in the genomes of all multicellular organisms and even some single-celled organisms, and as such constitute a large proportion of the non-coding or 'junk' DNA. A few may have been exapted for other purposes, but most are simply strands of viral DNA with a few mutations that broke them and rendered them harmless way back in our evolutionary history.

ERV's provide some of the most compelling evidence for common descent, especially since they appear at the same locus in the genomes of almost all members of a clade such as the vertebrates, including fish ancestors or the terrestrial vertebrates. The probability of the same ERV with the same mutations in in the same genetic locus to make it look like they form nested hierarchies, is vanishingly small, yet they do it over and over again.

The fact that they are present in all members of the same major clade tells us they must have been present in the last common ancestor of that clade, so they are a double embarrassment for creationists. They are both evidence of descent with modification and that there was no intelligence in the design of our genomes, because an intelligent designer would have no reason to include broken viral DNA which adds nothing by way of functionality yet must be replicated in every cell.