I too acknowledge my lack of expertise. I am a mathematician by trade
and my biological credentials are lacking. But, let me hazzard an
analysis of the possibilities.
Here are the alternatives for an explanation of the hierachy, let's
call it the __life_tree__, in the fossil record:
1. PROGRESSIVE CREATIONISM VERSION ONE. The _life_tree_ is studded
with miracles at all the major forks. The variation and selection
mechanisms are still at work, but the "sudden jumps" we seem to see
(at least I am told there are many places of apparent rapid change)
are the result of a miracle. This scenario is entirely consistent
with *junk* DNA and *vestigial* organs -- the result of the genetic
mechanisms which are still at work. "But a designer would remove this
junk and these vestigial organs at each miracle", I hear you say.
What basis is there for assuming a designer would want to do this? It
might not be part of his plan and purpose. God might be perfectly
content to leave the junk DNA and vestigial organs there. More
pointedly, perhaps God wishes to give those who do not wish to see the
creator, excuses not to do so? Evolutionary dead-ends are similarly
2. PROGRESSIVE CREATIONISM VERSION TWO. The _life_tree_ is studded
with miracles at all the major forks, but miracles of a more
naturalistic kind. Let me explain what I mean. With this
explanation, all the transitions are the result purely of genetic
mechanisms. That is, if somehow we could look at the entire history
of life, we would observe that everything could be described in purely
scientific terms - new species the result of a sequence of genetic
mutations and combinations. However, this history would be
*miraculous* in that the *probability*, in some sense, that genetic
mechanisms should produce the history we see, is extremely low. That
is, the fact that genetic mechanisms produced the _life_tree_ we see,
is viewed as a huge fluke. God has performed his miracles, not
through some undescribable process, but by causing a series of crucial
low chance events to occur. Some scientists view the natural
formation of life as being inevitable and common place, and thus
expect there to be life in many places around the universe. This
model views the fact that we have life as we know it on earth as being
amazing - either a big fluke, or the result of a designer, interacting
with his creation through the manipulation of chance. This model fits
even more comfortably with *junk* DNA and *vestigial* organs, for God
is only performing his miracles through the genetic mechanisms.
3. DARWINISM - GRADUALISTIC MECHANISMS. This model is the "standard"
evolutionary model. The _life_tree_ is the result of gradually
changing animal populations, this change being driven by natural
selection, and achieved via genetic mechanisms.
4. NON-GRADUALISTIC MECHANISMS. It is my understanding that various
non-gradual mechanisms to explain sudden changes in the fossil record
have been proposed. These do not, I believe, belong to the Darwinian
stable of explanation because the Neo-Darwinian explanation of why
genetics is able to produce the changes we see is that the
evolutionary mechanisms involved have had such long time periods over
which to operate.
5. EXPLANATION X. My final suggestion is that maybe we just don't
know enough yet to explain how the _life_tree_ came to be. Maybe
there are mechanisms at play which we simply haven't discovered yet.
I heard a radio documentary recently where they said Lamackian
(spell?) mechanisms have had a revival. That is, new research into
the immune system has shown that there are limited Lamackian
mechanisms at play and researchers have discovered biological
mechanisms which make this possible. Perhaps there are all sorts of
factors at play which we don't know about yet. We shouldn't fall into
the fallacy which says "We haven't got anything better, so Darwinism
must be right."
> I think most other ideas I have heard put forth are in general
> sweeping pictures which sound good but few wade into the messy
The above analysis is still in the realm of "sweeping pictures", but
my lack of expertise means that it is difficult for me to do
otherwise. But in any case, I think these "sweeping pictures" are
enough to demonstrate that it is reasonable to accept "common descent"
while remaining agnostic on the question of "mechanisms".
I hope this helps. Furthermore I hope that others who know more may
be able to comment on the above analysis.
"They told me I was gullible ... and I believed them!"