Punctuated Equilibrium: reviving the dead man?

Ami Chopine (amka@vcode.com)
Tue, 13 Apr 1999 13:40:52 -0700


> I offered PE as an example of Evolutionists patching the Theory of
> to save it from a failed test. Anyway, I haven't read the Talk.Origins PE
> FAQ, but I believe I'm failure enough with the doctrine to strongly
> with it.

Before you judge things, please read them. Otherwise, you may be thought of
as narrow minded. I sincerely hope this is not the case.

Does the FAQ address this:
Mutations are
> constant (usually not affected by the environment).


And, if the
> size is constant, then so is the selection/stress/pressure (this is
> essentially Darwin's argument for gradualism).

Hence the observation in the fossil record of long periods of statis, where
little or no evolution occured.

> Environment would really only affect the direction NOT THE RATE of
> evolution.


When the environment changes, the group of "good" mutations
> would change, but the rate would stay the same. If you're suggesting that
> number of mutations are somehow suppressed, not eliminated, in a
> until the right environment comes along --

I am not suggesting these mutations are suppressed. I am suggesting two
things: since under the pressures common to that population, that mutation
will not be selected for. Under some circumstances, given enough time, it
may gradually take over the entire population, much like diffusion. If
there is a direction, however..a stressor event, or the effective isolation
of part of the population in a slightly different enviroment then you will
see those mutations being selected for. What was once a slow, almost stand
still process, will become almost instantaneous in the geologic record.

how long can a population
> accumulate these mutations before it's forced to "evolve," assuming the
> environment never changes?

Without specific pressures selecting for those mutations? A long time.

And, if Evolution is true, how can there ever
> periods of stability (remember, there's always pressure and there's always
> mutations)?

When there is a basic equilibrium between the pressure and the species
original traits. The very great majority of mutations make no difference
whatsoever. They occur in non-protein coding DNA. Then also, the mutations
which do occur in the protein coding DNA may not even affect the protein.
The next group would be more likely to be harmful than beneficial. The
smallest group by far would be the potentially beneficial mutations (I say
potentially because they may make no difference at all until some unique
pressure appears).

> Sharks have stayed the same for millions of years (right?),

In a way, actually, that is wrong. There is more than one kind of
shark..there are many many species of shark. The appearance of a daughter
species does not mean the extinction of the parent species. Only if the
daughter species is so succesful within the same ecological niche that it
wipes out the parent species will that happen.

same with any
> the major groups of marine invertebrates. Of course, the ocean provides a
> very stable long-term environment. So, how did the marine invertebrates
> turn into fish, and the fish start walking onto the land, all the time the
> sharks just keep swimming around (not to say that sharks go back as far as
> marine invertebrates, they're fish). As far as I can tell, they evolve if
> they do, the don't if they don't.

Because, if a species gains a new ability, it will be more succesful. If it
can thrive in a more difficult enviroment, like air, then it has opened up a
whole new area of opportunity. The first land dwelling creatures had
virtually no competition. Therefore, they were very successful. And since
the ancestor species were also very succesful, they still thrive too.


Ami Chopine