Back in 2007 (you see I’m late, as ever) Allen MacNeill published a list of 47 sources of variation within living cells. I believe he’s since expanded it to over 50. As you’ll see from the link, his intention was to knock down an ID “straw man” that random point mutation cannot produce nearly enough variation to give natural selection traction. Every evolutionary biologist, he points out, can refute that from the hosts of other mechanisms now known to occur.
His critique of ID is a little unfair, I feel, having seen firsthand how often orthodox Neodarwinists knock down ID on the basis that point mutations are more than sufficient, or even unnecessary, to keep natural selection humming along. Certainly that is the case on BioLogos, where relatively little has been discussed in articles about epigenetics, gene splicing and so on. But he still makes a very cogent point. The year after his blog, MacNeill participated in a long and very fruitful (not to say educational and unusually good natured) discussion on this, and other, matters on Uncommon Descent. As he put it then:
…the engines of variation are more than up to the task of generating anything that could conceivably be of use to a living organism (plus an immensely larger amount of useless variation).
One point that didn’t seem to be raised in the ensuing posts was actually the first thing that struck me. To be more exact what struck me was the memory of an excellent song by Joe Jackson. The relevant image was of a man who hates the vast American hypermarket because he is actually paralysed by the amount of choice. That resonates with the experience of missionaries I’ve known who have returned from the developing world and find it physically almost impossible to do the shopping.
Too much choice is as inimical to selection as too little. It actually takes a great deal more mental sophistication to shop successfully in a megastore than in a small corner shop. It would seem to be possible that 50 or so random mechanisms generating enough variation to produce, say, the Cambrian explosion would swamp selection. The organism would drown in deleterious variations before any evolution could occur.
Another analogy might be a large archaeological dig such as those of Nineveh or Ebla, from which came large archives of cuneiform clay tablets. It can take so long to process and publish the results of such excavations that the original excavators will often not live to see the end of their work. It is not hard to envisage rampant variation stopping not only evolution, but life, dead in its tracks, in the same manner as mutation from ionising radiation.
And anyone working in a large organisation will be aware of the (false) quote from Gaius Petronius:
We trained hard . . . but it seemed that every time we were beginning to form up into teams we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.
Whether or not such catastrophe would occur in living organisms is, I guess, a mathematical question requiring also intimate knowledge of each process. But my use of verbal analogy is, maybe, partly justified by another MacNeill quote from the UD blog:
The idea that a field of inquiry isnt science unless it has some underlying mathematical model(s) is precisely the viewpoint that I am criticizing when I criticize the modern evolutionary synthesis. Yes, the mathematical models formulated by Fisher, Haldane, and Wright provided the basis for the modern synthesis, but more recent research has shown them to be inadequate models of biological reality.
That’s my excuse, anyway, and I’m sticking to it. Now MacNeill’s contributions laid some stress upon the non-directed nature of such variations in order to distance himself from his ID interlocutors. But it is clear from the rest of the UD conversation, and his other writings, that he is by no means a believer in totally undirected variation. On the contrary his criticism of the modern synthesis is because of its failure to grapple with the organisational sophistication of the cell, for which at one point he uses the term “artifical intelligence”. It was an ID respondent who suggest that “natural intelligence” might be a better term, and that either would vindicate the aims of Intelligent Design.
The upshot is that much recent evolutionary biology points to the cell’s active participation in restricting and guiding variation. Most think such variation remains “random with regard to fitness”, but even that shibboleth might some day be seen as a hangover from Neodarwinism. “Randomness” is hard to detect, and “fitness” impossible to define. Certainly there is increasing evidence that the environment can have an input into inherited characteristics, which has been anathema for many deacdes, though actually considered likely by Darwin himself.
What is undoubtedly the case is that a huge machinery of variation exists in living cells. That it could only produce chaos unless under the control of sophisticated mechanisms prior to natural selection seems difficult to dispute.