by Ryan Thomas

Created on: September 18, 2008   Last Updated: March 10, 2009

Over the past decade, evolutionists have touted the existence of alleged "junk" DNA as near indisputable evidence for evolution. Junk DNA is exactly what the name would imply: DNA sequences that appear to be extraneous, and therefore serve no purpose in the cell. It can consist of repeated DNA sequences, failed retroviral insertions, or introns, which are segments of DNA that are cut out during DNA to RNA transcription. Basically any DNA that does not code for a specific protein (or in a few cases codes for an apparently useless protein) is considered junk DNA, although more recently the term "non-coding DNA" has come into favor as it has been discovered that much of the DNA previously regarded as junk DNA does in fact serve in many important functions.

The existence of junk DNA found in the human genome is used to support evolution in a number of different ways. Many argue that it is a remnant of discarded evolutionary tools. This claim is very much akin to the vestigial organs argument. It basically holds that as a species population evolves, certain "primitive" DNA sequences may not be used, but will still be maintained in the species' genome for at least some period of time. Similarities in some junk DNA sequences between certain organisms are also used to support the idea of common ancestry.

The second major argument for common ancestry through junk DNA concerns what are called endogenous retroviral insertions. Retroviruses are viruses that, rather than inserting their own RNA into the host cell to carry out the viral protein synthesis, prefer to "reverse transcribe" their RNA into DNA, which is then spliced into the host cell's genome. Scientists have found DNA in humans as well as in many other organisms that shares a very striking similarity to modern day retroviral DNA. These retroviral DNA sequences appear in the human genome quite often, making up about 1% of the total human genome, and they represent about 30,000 different kinds of ERV's.

These supposedly useless DNA sequences appear to be the result of retroviral insertions where a particular virus has attempted to insert its own viral DNA into the host cell, but for some reason or another, the attempt failed. This failed insertion leaves something of a genetic "scar" on the DNA of the host cell, and if that cell happens to be a germ cell, this "scar" will be passed on through reproduction. It is therefore postulated that if an ERV is found in the genome of two species in the same loci on identical

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