Just read
this, an essay by Mark Pagel in Nature.
Other things I have read recently should by on the sidebar of this blog or you can look at them
here.
I thought it was an extremely well thought out essay, with some very original and creative ideas that brought to my mind other ideas I'd had in the past.
On the nature of intergenic DNA (normally called 'junk' DNA, although this name significant underepresents its importance in the genome).
- I agree that it is important for phenotypic regulation, and that it must be important in developing the complexity seen in phenotypically complex organisms (humans, trees, beetles).
- RNA may play an important role, and may be what most of this DNA is doing there (see work by John Mattick).
- I also believe intergenic DNA has physical importance in regulation, i.e. intergenic regions create novel promoter/enhancer elements, modifying polymerase assembly/transcription factor recruitment. Imagine shapes within shapes, of promoters enhancing TATA boxes to regulate transcription factor bound enhancement of ncRNA structures that catalyse RNA cleavage.
- Even though the previous point is entirely unproven (and mostly rubbish), you can't deny it all adds up to a whole lot of complexity.
I have to say though I didn't totally agree with some of his statements.
- He suggests analogue measurements are less precise, when it seems to me they can be more precise, and as long as you don't need to store analogue data (i.e. reduce its precision for storage e.g. rounding errors) then analogue will always be more precise.
In my opinion the genome cannot be encoded in an analogue way, but can be interpreted so. If you use an inexact system to read the digital genome you get an analogue result. E.g. transcription does not produce 10 RNA copies of a gene, it just transcribes it until the transcriptional machinery is no longer available or moves away.
Having said all of that though I do think that in regulatory systems, number/counts of molecules are important, and that concentrations often 'miss the point'. If an enzyme is at a very low concentration, there will be very few molecules of it around and therefore the chances of it bumping into its necessary reagents/cofactors etc. are not necessarily concentration dependant.
I think language is 'the voice of our genes' just as our brains are an adaptive strategy. The brain is a truly brilliant product of evolution. It allows us to evolve our behaviour, and to some extent our bodies, within our own lifetime, this is something that 'hard-coded' behaviour/instinct and non-plastic development cannot do. The only trouble is we can't pass it on to our offspring directly, we have to use language to tell our children about our experiences, so they can improve/modify them.
