> DC:>
> > We do not know whether we have seen the formation of a new major kind of
> > organisms or not. It takes too long for major groups to differentiate. An
> > observer in the Carboniferous would have had no reason to regard the
> > development of novel skull configurations (especially the development of
> > temporal openings) as especially exciting, but one group eventually led to
> > mammals, the other to reptiles and birds. We have to wait a few tens if
> > not hundreds of millions of years to find out which lineages will diversify
> > into a new major group, which will die out, and which will plod along with
> > little change.
>
> VJ: But this is precisely my point! You are prepared to accept, on
> trust, that such dramatic changes have occurred! In doing this, you, as
> a Christian and Bible believer, have created problems which can only be
> resolved by distorting the scriptures! In earlier posts I have drawn
> attention to the dangers associated with such an exercise (viz Ph.2:12,
> 2Pet.1:10, and 2Pet.3:16-18). Further, a careful reading of the word of
> God - as you must be aware - reveals that the all-too-popular notion,
> 'once saved, never lost', is founded on sand.
My post may not have been clear. We do not know if we
have seen a new major kind appear within the period of time during which
we have been studying living organisms. The fossil record shows excellent
evidence for the development of one major kind from another. However, it
is only in retrospect that we can look back and see that a certain point
was the beginning of a major group. True mammals did not evolve from the
synapsid line for about 80 million years, although within about half that
time the synapsids would probably have been recognized as a significant
division within the amniotes. The change is very gradual. After the
appearance of the first reptiles, some relatively slight changes in the
configuration of the skull bones are our first clue (in hindsight) that we
are looking at our lineage. Further development of the skull includes
variation in the form of the teeth and growth of whiskers, if not more
extensive hair. In the body, there is a gradual shift towards a more
efficient upright quadrupedal stance and a reduction in lower ribs
(suggesting development of a diaphragm, which is needed for more efficient
breathing). The configuration of the jaw bones changes, with the back
bones of the lower jaw becoming reduced and moved. Eventually, there is a
double jaw joint, with both the reptile-like and the mammal-like in the
same individual. Finally, the joint becomes fully mammalian, with the
other bones reduced and becoming part of the auditory apparatus. Some of
these transitions in the jaw can also be seen in the development of modern
mammalian embryos. Once the jaw joint had switched, the new forms are now
considered mammals by most systematists. (Some want to use a different
definition of what is a mammal and thus draw the line higher up; if
anyone is into systematics, crown-group definitions would do this. I
think crown-group definitions are a bad idea for various reasons, but
that's off-topic. The fact that the proper classification of these is
debated reflects their transitional nature as well as the current
contentiousness of systematics.) Modern monotremes such as the platypus
and echidna retain a number of reptile-like or transitional features that
have changed in most modern mammals, such as laying eggs, poor
thermoregulatory ability, and poorly developed nursing (no nipples, milk
less well-developped). Thus, we can see the gradual development of a
major group in the fossil record. Similar examples could be given for a
variety of groups, but because we are mammals, fossil mammals have been
particularly well-studied.
Similarly, the patterns of molecular systematics point to the derivation
of major kinds from each other. The 18S gene codes for ribosomal RNA,
used to make proteins. It is basic to cell function, so everything
needs a copy (usually many), and it does the same thing in everything, so
there is no particular need for our gene to be more similar to a mouse
sequence than to a mushroom sequence. In bivalves, there are five
generally recognized subclasses. The 18S sequences of clams within a
subclass are more similar to each other than to clams of other subclasses,
but they are in turn more similar to other clams than to other kinds of
mollusks. Within the subclasses, the evolution of various orders,
families, and genera can be traced using this gene.
ancestry of major kinds of organisms. From the Bible, I see clear
evidence that creation reflects the glory of God and little evidence about
how He created things.
Your last point is an example of the passages that can be a problem for
straightforward reading. Rom. 8:38-39 declares that nothing can separate
us from the love of God, which sounds rather like once saved, always
saved. My belief is that once saved, never lost. The warnings against
falling away are then interpreted as cautions for self-examination, that
we may not fool ourselves into believing that we are saved when we are
not, and warning against the dangers of neglect of the faith. Actions
prove the existence of faith, as James argues, so we cannot assume that
an experience at some past point was a truly saving event without its
having an ongoing effect on ourselves. Not that I think we will resolve
the debate between Calvinist and Arminian views here, but that careful
study by Christians has produced disagreement on this point.
David C.