Many thanks to Umberto Lombardo, Sicilian-born Scientist and all-round good egg. He posted a courteous and thoughtful comment to my previous post, which you can read below.
I am imposing on your patience by developing my reply to his comment.
He explains the "mechanism" of Darwinian evolution by saying that we see it on a short timescale in bacterial resistance to antibiotics or insect adaptation to agrochemicals: all examples of the same Darwinian evolutionary mechanism, which on a multi-million year timescale produces widely divergent species of plants and animals. If the mechanism can so do so much in days/weeks/months, why should we be surprised to see what it can do over aeons?
In my view the analogy breaks down, thus:
When you have a penicillin injection to counter a bacterial infection, you and the doctor hope that all the bugs will be wiped out. In many cases they all are – case closed.
But there may be some bugs which are immune to the drug; just as some humans are immune to plague – if this were not the case, Europe might well have been totally depopulated by the Black Death.
So you get your shot, killing most of the enemy; but some of the invaders survive. These lucky ones now have your body to themselves and run riot. If you live long enough to infect somebody else with them, the doctors will not be able to use penicillin. They will try other antibiotics but the same thing may happen again – and we end up with MRSA etc.
My point is that the resistant bacteria are not members of a new species – no new genetic information has been created. It was all there in the original population.
Similarly in the geneticists' laboratory: they bombard fruit flies with radiation and get one of three outcomes – normal fruit flies, mutant fruit flies or dead fruit flies. What they don't get is a new species of fruit fly. Nearly all mutations are harmful or, at best, neutral.
I think it is far-fetched to explain the development of birds from dinosaurs (or whatever) in terms of random mutations and natural selection.
I complained that the "fossil record" does not support Darwin. Umberto says that this is "because the vast majority of fossil deposits have been buried, destroyed, eroded." He is in good company – Darwin said the same. Animals with soft bodies are not as likely to be fossilised as creatures with bones or shells.
The Earth is about four-and-a-half billion years old – about a third the age of the Universe. For a very long time it was too hot to sustain life, let alone bring it forth. But the fossil evidence indicates that almost at the moment it cooled sufficiently, about three billion years ago, life forms appeared. The fossils are of soft-bodied single-celled creatures – just the sort that might be expected to have been destroyed. We have more single-celled fossils for the next two-and-half billion years.
Then just over half-a-billion years ago came the Cambrian Explosion. In a lousy 5-10 million year period, an astonishing variety of multi-celled creatures appeared, some of whose fossilised remains we have found and classified. These creatures have no apparent ancestors.
My question was: do marsupial wolves and placental wolves share a common (proto-wolf) ancestor, or do marsupial wolves and kangaroos share a common (proto-marsupial) ancestor?
Umberto answers: marsupial wolves and kangaroos share a common (proto-marsupial) ancestor. The similarity between, marsupial wolves and placental wolves is accounted for by similarity of the ecological niches occupy.
Here is me being frivolous (in serious sort of way): Lastly, and here I shamelessly appeal to the argument from personal incredulity: The marsupials stage a tragedy, Hamlet – The hero's father is murdered by his uncle... At about the same time the placentals (who occupy a similar ecological niche) coincidentally publish a play, Haammlett – The hero's father is murdered by his uncle... Well, you may have a mechanism but...
Umberto: The evidence that does not fit in the theory is the basic motor of scientific progress.
Me: Agree 100%.
Umberto: If we start to use it as a proof of the existence of God, then scientific progress stops.
Me: I regard inconvenient evidence as destructive of inadequate theories. If there are people who use it to "prove the existence of God", they are benighted. If there are those who say that the discovery of information in DNA is consistent with a designing intelligence, I have no quarrel with them. If they have an understanding of God that comes from Philosophy, Theology and the Mystics, I'm one of them.