"Macroevolution" is simply a convenient way of indicating that the observed
changes are large-scale rather than small-scale. The danger with this term
comes in believing that this is a different kind of evolution, separate from
and independent of "microevolution". The evidence demonstrates that this is
not the case; therefore we could just as easily refer to "macoevolutionary"
change as large-scale evolutionary change. It would say the same thing, but
we would also recognize that it is still the same kind of basic change as we
see on a smaller scale as with the peppered moth.
>One doesn't have to delineate mechanisms to argue for macroevolution. Just
>pointing out the geological instantaneousness of the Cambrian explosion, in
>to the observable modes and rates of evolution, makes a strong case.
Compared to geological time, nearly all the observed instances of modern-day
"macroevolution" (such as speciation) are also "instantaneous". Besides,
the "instantaneous" nature of the Cambrian explosion is an illusion caused
by the lack of fossil evidence prior to the event. The recent discovery of
fossilized embryoes demonstrates that many of the Cambrian forms existed in
the Precambrian, side-by-side with the Ediacaran fauna, and there is the
even more recent announcement of a possible ancestor to the Cambrian fauna
(Science 283:1919-1923 [3/19/99]). All this indicates that the explosion
was not quite so "instantaneous" as the geological timetable might lead us
However, even if the Cambrian fauna did appear "overnight" geologically
speaking that would not rule out the fact that these "rapid" large-scale
changes were caused in part by mutation of duplicated genes (both
"microevolutionary" mechanisms; the absence of which would make any form of
"macroevolutionary" change impossible) filtered by natural selection.
>tend to be smug in the claim that microevolution explains it all.
No evolutionist -- not even myself -- has ever claimed that "microevolution"
[mechanisms] explains it all. What we have said is that "macro-" and
"microevolution" are all one and the same as evolution as a whole, and that
the different mechanisms responsible for small-scale and large-scale changes
are not mutually exclusive or independent, but work cooperatively together.
>science a service when they make challenges based on this valid point.
Except that as I have pointed out in this post and explained in my previous
post, this is NOT a valid point, but a tactic invented by creationists to
attack evolutionary theory. You don't have to take my word for it, Cliff;
check it out on your own.
And while you're at it, read the scientific literature. It will show you
how research into small-scale mechanisms makes it posible for us to
understand how large-scale changes occur. The textbooks of Douglas Futuyma
in particular do this very well. Don't rely on the ignorance of others for
your information; investigate it for yourself.
Kevin L. O'Brien