Responding to Moran – Is “Unguided” Part of Modern Evolutionary Theory?
|August 12, 2012||Posted by johnnyb under Intelligent Design|
I am always aghast that in the 21st century people still make the claim that mutations are unguided. This is a hold-over idea from before the discovery of DNA, simply because some mutations were found to occur independently of selection.
However, modern evidence has showed that mutations are actually in large part due to mechanisms geared for adaptive purposes, just like the rest of biology. And, just like hearts have heart attacks, mutation systems can break down, too, and lead to disease. Just like bacteria, we discovered mutations first by noting the ones that were causing disease, but with every closer look we see that these are the exception rather than the rule.
To point to a simple example (and one that is even often used as definitive evidence of the efficacy of random mutations!) let’s look at the somatic hypermutation process in the immune system. When a new bacteria invades the body and causes an infection, the body must generate a new gene. So what does it do? It takes a close-fitting antibody gene and mutates it. Now, first of all, you should notice that the mutations only happen in the correct gene – the antibody gene. That’s 1,200 base pairs out of 3,000,000,000. But that’s not all – it also focuses mutations on the part of the gene that attaches to the antigen, not the part that signals the cell (because otherwise it wouldn’t signal the cell correctly). So, that’s roughly 600 base pairs out of 3,000,000,000. The mutation system is highly selective of the sites that it mutates, skipping over the cell signaling systems and focusing on the part that is specific to the antigen.
So, therefore, in this scenario (which is one of the best-studied), teleology (goal-directedness) accounts for 99.99998% of the specificity of the mutation, and randomness / unguidedness / happenstance accounts for 0.00002% of it. Yet somehow the myth persists that we have good evidence that mutations are random.
For more information on this issue, you might be interested in a UD series I did on the modern synthesis and the video below:
P.S. I originally tried to post this comment on Moran’s blog itself, but was having technical difficulties. So, if it winds up in his moderation queue three or four times under different accounts, I’m sorry, I was just trying to get it posted.