tornapart - If you look back to the early pages of this thread you will see that we all agree that the term "junk DNA" is unhelpful.
Our genome consists of about 3 billions base pairs and so far we know exactly what 60% of it is for.
1.5% codes for proteins
4% is regulatory DNA
10% is structural DNA - centromeres and telomers which compensate for a substandard copying mechanism
All of the above 15.5% is essential.
However......
21% are LINEs Long Interspersed Nuclear Elements (parasitic)
13% are SINEs Short Interspersed Nuclear Elements (parasitic)
8% are ERVs Endogenous RetroViruses (parasitic)
3% are DNA Transposons (jumping genes, also parasitic)
All of this 45% of our genome arose in our ancestors through various types of copying errors.
As I explained previously there are enzymes called "reverse transcriptase" and "integrase". These function like a "copy-and-paste" function in a word document.
Try copying a chunk of text from any file and then hold down Ctrl+V and seee how quickly the document gets very long.
Most other species also have lots of parasitic DNA in their genome. The onion Alium altyncolicum has double the DNA we do and a very similar species of onion Alium ursinum has TEN times as much.
There are species of rice that have bigger genomes than humans.
So is it OK to call this 45% junk? Well yes it probably is but with a proviso. It does provide raw material that future mutations may turn into useful code. I keep promising to write about our opsin genes which are a great example of this - I will soon.
The remaining 40% is currently unknown - its why geneticists get up for work on Monday mornings. Some of what remains will no doubt have functions and some of it may be other forms of parasitic DNA.
Jonathan Wells is a Moony - his studies were sponsored by Rev Moon specifically for the purpose of attacking evolution for purely theological - in this case cultish - reasons.
His book will provide lots of examples interesting functions of parts of our genome whose function was previously unknown and he will try to give you the impression that therefore all non-functional DNA has a purpose. For all the reasons I have explained above and more - it doesn't. We know precisely how the "bloat code" originated and it was not put there by any designer.
If you look back to my posts about transposons LINEs and SINEs you will see how they in fact provide very powerful evidence of common ancestry.
