nygreenguy wrote:otseng wrote: I’ve given several examples of functions for ERV. So, how can a virus infect a reproductive cell, mutate to become inactive, yet also mutate to have a beneficial function in the host organism? ERV are supposed to be at best functionless, not impart a beneficial function.
Argument to incredulity?
ERV has historically been labelled as “junk DNA” and assumed to have no purpose.
Endogenous retroviruses provide yet another example of molecular sequence evidence for universal common descent. Endogenous retroviruses are molecular remnants of a past parasitic viral infection. Occasionally, copies of a retrovirus genome are found in its host’s genome, and these retroviral gene copies are called endogenous retroviral sequences. Retroviruses (like the AIDS virus or HTLV1, which causes a form of leukemia) make a DNA copy of their own viral genome and insert it into their host’s genome. If this happens to a germ line cell (i.e. the sperm or egg cells) the retroviral DNA will be inherited by descendants of the host. Again, this process is rare and fairly random, so finding retrogenes in identical chromosomal positions of two different species indicates common ancestry.
These endogenous retroviruses (ERVs), contrasted with exogenous ones, now make up 5-8% of the human genome. Most insertions have no known function and are often referred to as “junk DNA”.
And let me add that assuming ERV has no purpose has actually slowed down scientific progress.
Junk DNA, a term that was introduced in 1972 by Susumu Ohno, was a provisional label for the portions of a genome sequence for which no discernible function had been identified. According to a 1980 review in Nature by Leslie Orgel and Francis Crick, junk DNA has “little specificity and conveys little or no selective advantage to the organism”. The term is currently, however, a somewhat outdated concept, being used mainly in popular science and in a colloquial way in scientific publications, and may have slowed research into the biological functions of noncoding DNA.
Now that recent research has shown that ERV can have a function, it falsifies the original assumption that ERV is junk DNA.
I would agree that if ERV is functionless, it would be better explained by some random process of virus DNA/RNA insertion than design. However, since science is now revealing that ERV have function, it is better explained by design.