Re: tears

H. M. Hubey (
20 Oct 1995 17:56:51 -0400

David Froehlich <> writes:

>Have you ever heard of kidneys? These seem to be much better at getting
>rid of excess salt. Isotonic tears are not an efficient method of
>loosing salt, urine is.

So what? We're discussing something else.

Besides which, if you are living in a marine
>habitat where is this fresh water coming from?

1) I didn't say that they never drank fresh water.
2) Even if they had adapted to salt water, the kidneys could have
changed over time, and probably faster than bones.
3) It could have been an estuary or a lake, maybe even a swamp.

And we could ask the same question for the grassland dwellers.
OF course, they'd need to hang around water. The question is
one of degree.

>So what? Producing isotonic tears as a salt excretion mechanism only
>works if you have voluminous amounts of fresh water. The energetics of
>the situation (you would have to expend a lot more energy to expel salt
>in this manner than with concentrated mechanisms such as using the
>kidneys) would seem to indicate that the use of isotonic tears is
>extremely unlikely.

It's unlikely that they didn't have kidneys! They urinated like
every other animal. The question is not about that so don't twist
it out of shape into a straw man. Just because the complete
answer is not there doesn't mean that there isn't something
there that's strange an unusual. We still have the problem
of tears that seems to be associated with emotion and also
with animals that seem to have water affinities. Can we call
this "affinity" aquatic or semi-aquatic and get it over with
instead of fighting over wading, dunking, splashing...

>organism out (ie an increase in the length of the loop of henley).
>Interestingly, there is no evidence of this change. I wonder what AAS
>proponents make of this anotomical structure? To my eyes it seems to
>falsify the AAS position (at least for AAS in seawater). Any comments?

Sure. The extra salt due to salt water could have been the
reason for the tears. You already have animals that have
working kidneys, and you might have a marginal problem with
salt. The weeping could have been the extra little thing needed
to keep the salt balance. The habitat could have been an
estuary or something like that periodically flooded with sea water.
I don't know how one would go about forcing animals to live in
salt water and then studying the effects of the salt in the water.

I suppose we could look at sea otters, polar bears, penguins and
other animals..

Any information on these?


Regards, Mark