Re: Tears

Alex Duncan (
9 Jul 1995 17:27:32 GMT

In article <3tniep$> Pat Dooley, writes:
>How big is your computer? The area is fraught with difficulties because
>other primates don't weep copiously, whereas humans actually have
>two types of tears. Check out William Frey on the subject.

I had the good fortune to speak to an opthomologist on friday night. As
you might expect, I asked him about tears. According to him, tears have
several functions, most of which I suspect we already know. I also asked
him about the saline content of tears. He told me that the salinity of
tears exactly matches the salinity of other bodily fluids and excretions.
Apparently, this is especially important for the eyeballs, which would
otherwise be subject to dessication due to exposure to air. Apparently
this has a lot to do with osmotic action across membranes (which I don't
understand well). If the salinity of tears was either greater than or
less than that of the inter- and intracellular fluids of the eyeball,
then the eyeball would be at risk of losing either fluid or saline. Loss
of either of these substances would impede ocular function.
So, does the salinity of human tears differ from that of the
tears of other mammals or primates? My opthomologist (sp?) friend was
skeptical. Do we have some reason to think that the usual saline content
of the human body differs from that of other mammals? I doubt it, but as
always, am ready to check any references someone might provide me.

Alex Duncan
Dept. of Anthropology
University of Texas at Austin
Austin, TX 78712-1086