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Re: Sauroparental care

On Sun, 21 Dec 2003, Ken Carpenter wrote:
> Again, I raise the point of how do you test your hypothesis? I can just
>as as well say that little green men come to earth and took care of the

I agree that at the present state of evidence we can only make inferences
about parental care.  I must disagree about the _strength_ of the
inference.  In my view parental care is a strong inference--so strong that
we can assume it happened.  Behaviors don't fossilize.  Maybe we can never
prove it.  However, in terms of helping us derive hypotheses, I wonder at
what point does an inference become so strong that a broad consensus
exists that we can assume it happened?
I'm trying to think of an analogy.  Parental care--i.e., increasing
investment in egg and therefore baby (once an organism has invested
considerable time and effort in an egg it pays to maintain investment in
baby!) seems to have increased over evolutionary time.  Indeed, it
requires greater behavioral flexibility/intelligence/memory, etc. to
carry out (e.g., only in a Larsen cartoon can one imagine bacteria in
school).  Of course there are exceptions, but in general parental care is
very much the plot line of vertebrate evolutionary progression.  Parental
care has important advantages for predator protection and nutrition.  In
most cases, animals that possess the ability to protect their young will
do it.  I realize that this is not necessary in all species.  But it
is in most terrestrial quadrupeds over a certain size.

I wonder if the acceptance of endosymbiotic origin for mitochondria and
chloroplasts is a good analogy for what I'm trying to argue.  It was a
fringe idea.  It couldn't be observed (although it could be in
lichen and such, i.e., extant analogues).  It left no fossil record.  But
disparate lines of evidence were so convincing that the inference became
a widely held assumption.

If one cannot have direct evidence of something, what is the next best
thing?  And at what point does the need for empirical evidence become
superceded by the quality of indirect evidence?