[net.origins] Horsefeathers

dubois@uwmacc.UUCP (Paul DuBois) (03/25/85)

> [Jeff Sonntag]
> Paul Dubois, writing on the (mistaken) idea that when a new specie 
> evolves, all members of the parent specie must die out:
> > Evolutionists developed the idea.  Some evolutionists realize this, some
> > (as, apparantly, Bill) do not.  Some creationists realize this, some do
> > not.  Some creationists realize that it is not necessary to evolutionary
> > theory, some do not.
> > 
> > But whether the idea is true or not, it *is* the case that a number of
> > proposed intermediates have been rejected as such (by evolutionists) on
> > the basis of EXACTLY the above reasoning:  a form is not transitional to
> > another form if it exists contemporaneously with it.  Lungfish, for
> > example.  My beloved coelecanth, for another.  Archaeopteryx is under
> > the same pressure since the discovery of other fossils which are clearly
> > birds contemporary to it.

>      It really doesn't matter *who* has accepted the idea that a form is not
> transitional to another form if they exist contemporaneously.  The idea simply
> doesn't stand up to examination.

Fine.
I was not concerned to demonstrate the validity or invalidity of the
idea that when species evolve the parent species must die.  I was
concerned to demonstrate that the idea did not originate with
creationists, so it is an evolutionist FALLACY to imply that it did.
Really, for all the times that we hear in this newsgroup that
creationists attact a mistaken notion of what evolutionists believe,
I sometimes wonder if even evolutionists know what evolutionists
believe.

> Archaeopteryx may or may not have been
> the link between reptiles and birds, but the fact that Archaeopteryx hadn't
> died out before birds developed HELPS TO SUPPORT THE IDEA THAT ARCHAEOPTERYX
> was the parent specie.

That fact alone has nothing to do with support for your contention.  It
must be bolstered by additional assumptions.  Other possibilities,
equally plausible from the sequence in the rocks, are that both
descended from common ancestors, or that Archaeopteryx descended from
more well-developed birds (e.g., McGowan thinks the Ostrich degenerated
from more well-developed birds) or that Archaeopteryx and other birds
have no common ancestor.  Which of these are inconsistent with the
fossils, or less consistent with the idea you claim they support?

> Birds could hardly have developed from Arch. if Arch.
> had died out before birds developed.  It's almost a tautology.  Yet Paul
> tries to get us to deny the possibility of Arch.'s intermediate status
> (not solely) on the basis of it's contemporaneousness with birds, a fact
> which actually *lends support to* it's intermediate status!

I did no such thing.  I stated that the line of reasoning has been
used by *evolutionists* as evidence against certain forms being
transitional.

>      Just what would you require of an intermediate specie between birds
> and reptiles, Paul?  You criticized Arch.'s feathers as being almost
> identicle with modern bird feathers.

I didn't "criticize" the feathers.  It's simply a fact.  What do you
want me to say about them?  That they're NOT identical with modern
bird feathers?

> You want maybe some sort of useless
> half-feather?  Why would something like that be selected for?  Why would
> you expect a specie with useless features to survive long enough to leave
> any kind of fossil record?

Like the Irish Elk?

I assume from what you say that we *wouldn't* expect intermediate
features, that we must go from one developed structure to another
- no incipient features.  Would we, then, expect instantaneous
appearance of fully developed feathers? Anything less would not be
selected for?  Or what?
-- 
                                                                    |
Paul DuBois	{allegra,ihnp4,seismo}!uwvax!uwmacc!dubois        --+--
                                                                    |
                                                                    |

ethan@utastro.UUCP (Ethan Vishniac) (03/26/85)

> 
> > You want maybe some sort of useless
> > half-feather?  Why would something like that be selected for?  Why would
> > you expect a specie with useless features to survive long enough to leave
> > any kind of fossil record?
> 
> Like the Irish Elk?
> 
> I assume from what you say that we *wouldn't* expect intermediate
> features, that we must go from one developed structure to another
> - no incipient features.  Would we, then, expect instantaneous
> appearance of fully developed feathers? Anything less would not be
> selected for?  Or what?
> -- 
> Paul DuBois	{allegra,ihnp4,seismo}!uwvax!uwmacc!dubois        --+--

It is an interesting problem to speculate on the origin of highly
specialized structures.  Indeed, evolutionary theory would lead us to
expect that they should have developed from other structures that conferred
some definite advantage to the organism that posessed them.  From this
point of view the features that allow birds to fly are most fascinating.
At first glance nothing would appear more useless than a partially developed
bird.  However, upon further examination we see that the issues involved are
more subtle.  Consider the feathers of that strange beast.  There is nothing
bizarre about a non-flying creature having feathers.  They are a reasonably
good form of insulation.  This tells us, incidentally, that Archeopteryx
was probably warm-blooded (insulation is not a good idea for a creature that
needs exposure to the sun to warm up).  What is interesting about Archeopteryx
is that it has feathers that appear to be structurally modified for flight.
In other respects, Archeopteryx is not well adapted for flight.  Its lack
of a large breastbone and the unfused nature of its skull and backbone
show that it had not yet minimized its body weight and adapted for powered
flight.  It could have been an adequate glider.  The evidence from its
claws that it was a tree climber is particularly suggestive in this respect.

What does all of this suggest?  On evolutionary grounds we would expect that
there was a preceding species with feathers for insulation, but without the
wing feathers (I forget the technical term) necessary for flight.  Although
such feathers are not well preserved by fossilization we do expect them to
turn up eventually (even the "hair" on pterosaurs has been preserved in some 
specimens).  Could it have coexisted with true birds?  Only if it could
sucessfully compete within some ecological niche.  Since there are 
tree-climbing gliders around today this doesn't seem improbable.  The peculiar
combination of features seen in it indicate that if it was not a direct
ancestor of modern birds, it was still closely related to such an ancestor.
I note in passing that there is no firm evidence that it did coexist for any
length of time with essentially modern birds.  

The point of the above is that there is nothing about the development of flight
that requires that all of the necessary adaptations be made at once.  No
species represents a truly "perfect" adaptation.  Archeopteryx, like others,
was adequate, given its resources and its competition.


"Don't argue with a fool.      Ethan Vishniac
 Borrow his money."            {charm,ut-sally,ut-ngp,noao}!utastro!ethan

*Anyone who wants to claim these opinions is welcome to them.*

mrh@cybvax0.UUCP (Mike Huybensz) (03/26/85)

In article <827@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes:
> I was not concerned to demonstrate the validity or invalidity of the
> idea that when species evolve the parent species must die.  I was
> concerned to demonstrate that the idea did not originate with
> creationists, so it is an evolutionist FALLACY to imply that it did.
> Really, for all the times that we hear in this newsgroup that
> creationists attact a mistaken notion of what evolutionists believe,
> I sometimes wonder if even evolutionists know what evolutionists
> believe.

Nobody knows what any large group really believes.  Look at the controversy
in net.religion.christian over what a christian is.

Yes, there are fallacies about evolutionary theory, some of them constructed
by all-too-human evolutionary scientists.  However, when creationists bring
up generally discredited fallacies as straw men, they are misrepresenting
current evolutionary thought.

Should I quote past fallacies of Christianity, such as flat-earthism, cite
distinguished theologians and some modern supporters, claim it is
representative of modern Christian belief, and claim it as support that
belief in god is an error?  No.

But the flat-earth example is analogous to creationist arguments based
on erroneous ideas about evolution like non-contemporaneity of parent and
offspring species.

> > Archaeopteryx may or may not have been
> > the link between reptiles and birds, but the fact that Archaeopteryx hadn't
> > died out before birds developed HELPS TO SUPPORT THE IDEA THAT ARCHAEOPTERYX
> > was the parent specie.
> 
> That fact alone has nothing to do with support for your contention.

Paul is correct here.  Dates of occurrence in the fossil record tell little
about individual ancestry questions because the fossil record is so incomplete.

> > You want maybe some sort of useless
> > half-feather?  Why would something like that be selected for?  Why would
> > you expect a specie with useless features to survive long enough to leave
> > any kind of fossil record?
> 
> Like the Irish Elk?

What useless features do you think the Irish Elk had, Paul?  Why do you think
they were useless?

> I assume from what you say that we *wouldn't* expect intermediate
> features, that we must go from one developed structure to another
> - no incipient features.  Would we, then, expect instantaneous
> appearance of fully developed feathers? Anything less would not be
> selected for?  Or what?

You assume incorrectly.  Intermediate features may be useful and selected
for.  Anyone who has worked with insects has seen numerous groups of insects
showing full ranges of development from rather generalized species to
highly specialized species with tremendous anatomical modifications.
The incredible number of insect species provides clearer examples than the
small number of large animal species most people are familiar with.  Specific
groups to look at include ants and treehoppers.
-- 

Mike Huybensz		...decvax!genrad!mit-eddie!cybvax0!mrh