Re: The use of offensive weapons (was Re: ANKYLOSAUR CLUBS *)

[ornstn@inforamp.net (Ronald Orenstein)]

>Actually, the opposite is true.  Biologists have been able to show
>that every part of an animal is there for some reason.  Granted,
>there is some preadaptation function involved in the generating of
>the part in the first place, but the refinement (and ultimately the
>keeping of the part) is because it is serves some purpose.  Any part
>of the animal which isn't needed is subsequently lost.

This is simply not true.  For one thing, vestigial structure may persist for
a long time (otherwise please explain the function of a kiwi's wings, the
vestigial toes on certain fossil horses, your vermiform appendix etc.).
Secondly, we certainly know that at the molecular level at least there is a
lot of evolutionary "garbage" in the form of unexpressed or otherwise
nonfunctional DNA.  Even vestigial behaviour can persist, as in Lauterbach's
Bowerbird of New Guinea which displays a head ornament that it no longer has
in the same fashion as its close relatives that have retained it.

And it is certainly not the case that "Biologists have been able to show
that every part of an animal is there for some reason"; otherwise we would
have explained the function of every animal adaptation, and we have
certainly not done that yet!

>This isn't as big a stretch as one might think.  Structures that
>form, and are subsequently kept, do so because it gives the animal
>an adaptive advantage which helps insure a mate.  Ultimately,
>competition in evolution comes down to whether an animal gets it's
>genes into the next generation (literally a life or death issue).
>This is why there are a wide variety of display/threat/bluff
>features found on all vertebrate groups.  This is also why any
>weapon will ultimately be used to fend off members of the animals
>own species.  Anti-predator function is simply an extra benefit.

Do you have ANY evidence for this statement?  I doubt it.  Do you consider a
porcupine's quills (for example) to have evolved for dealing with rivals,
and only later developed an anti-predator function?  If so I would love to
see the references.  Also there are many structures (ie a bird's wings) that
could NOT have had their current function in the early stages of their
evolution because they needed to be a certain size or structure first.
True, animals need to reproduce, but that is not the only thing they need to
do and they won't get a chance to do even that if they do not survive to
sexual maturity.  Defence or prey-capture mechanisms are every bit as
crucial to an animal's reproductive fitness as adaptations directly involved
with mate selection, and there is no way that you can make a blanket
assumption that one always is the primary selective force acting on
morphology, with the other bringing up the rear.

>The pronghorn was simply one example.  There are millions of
>examples (one for each species) which back up my statements.  Every
>single time that one finds an unusual part on an animal (especially
>if it could be used as a weapon), it is ultimately designed to be
>used against it's own species.

This is absolutely unprovable and almost certainly false.  Please consider
the following:  the venom apparatus of snakes; the stings of bees and wasps;
the quills of porcupines; the claws on the front limbs of anteaters; the
tentacles and suckers of cephalopods; the poisonous spines of many fishes;
the enlarged jaws on the guard castes of army ants (etc) - I defy you to
cite research citing that ANY of these evolved first and foremost for
intraspecific combat.

>This has also been shown for many dinosaur groups.  Horns in ceratopians,
>hornlets on theropods, and the thickened skull on pachycephalosaurs are simply
>some of the examples of features found on the animal which are primarily used
>for intraspecies combat.

You have NO WAY of determining this except by inference, unless you have a
time machine you haven't told us about.  It may be possible or even probable
that they served this purpose, but you simply cannot make such statementsas
though they were proven certainties.

>Do catfish use the spines against their own species?  If so, it
>would be another point for me.  These spines would certianly be
>useful in solving a territorial dispute.

As far as I am aware, NO.  They do not.  Point against you, I'm afraid.

>Rob

I hate to say this, Rob, but I'm afraid your degree of certainty far
outstrips your biological knowledge or understanding of evolutionary
processes.  May I respectfully suggest you do a little reading in the area
before making such pronouncements?  And if you come up with evidence that
you are correct please post it - and I mean that your GENERAL statements are
correct.  We all know of adaptations that are indeed primarily used for
interspecific combat, but you have a long way to go to persuade me that ALL
weapons serve this purpose.
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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