Tuesday, May 17, 2005

I had a nice email about this article today which explains how the genetic code must be part of the fabric of the universe rather than something that can have evolved. I am also reading Alister McGrath's Dawkin's God, which is a critique of Richard Dawkin's non-scientific thoughts. You may remember I discussed a talk McGrath gave at Cambridge a few months ago. I'll have some more on the book when I've finished it but it looks good for now.

Another thing to consider is the question of mutations. These are random changes to DNA that are then passed on to the next generation. It is the effect these changes have on an organism that provide grist for the mill of natural selection. But are the mutations actually random? They are certainly usually assumed to be although in fact, they have causes such as radiation or chemical reactions. Also, some genes are more prone to change than others which is why some genetic illnesses are quite common and some very rare indeed. A mutation is essentially a chemical reaction and how easily these happen depends on the stability of the molecules involved. Some mutations happen more easily than others because some DNA arrangements are inherently less stable than others.

This raises an interesting point. In the long run, all mutations should tend towards the most stable arrangement of DNA. Even if that arrangement is not genetically viable (and it probably isn't), there will still be a tendency to move in that direction. This might be part of what junk DNA, that has no direct genetic effect, is doing. On the other hand, it might be that the 'higher' animals have more stable DNA than lower ones simply because theirs has mutated further towards the theoretical arrangement of maximum stability. If that is the case, then it would mean that there was a built in tendency in nature towards the higher animals. It would also leave us asking where that tendency might have come from.

I do think it would be worth measuring the relative chemical energies of different types of DNA, or perhaps it has already been done in which case I'd love to see the results.

Comments or questions? Post them at Bede's dedicated yahoo group.

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