Re: Morgab tears /salt

Alex Duncan (
16 Nov 1995 14:44:08 GMT

In article <48fe17$> Thomas Clarke, writes:

>Thus you prefer an explanation which invokes conditions that only
>obtained in the past 10,000 years or less, or with a bit of hand
>waving in the past half a million.
>I don't think anyone has yet commented on my suggestion that there
>is a tendency among PAist to favor explanations for ape/human
>differences that place the changes as late as possible.
>I think you reaction to the stipulated tear composition problem
>illustrates this. Putting aside the AAT explanation, explanations
>could be thought up based on exposure of the eyes to windblown dust
>on the savannah etc that would place the change much further back in time.

Actually, I considered the "dust on the savanna" idea as well, but
thought the "population density" argument made more sense, for a reason I
can't remember now. If the reason doesn't come to me by the time I've
finished typing, then I'll have to concede that the "dusty savanna" model
makes just as much sense.

Well -- hold on: we're looking for an explanation not just for tearing,
but for tears which might contain a high proportion of infection-fighting
enzymes. A capacity to produce large quantities of tears might be
selected for in a dusty environment, but would they necessarily be tears
w/ lots of lysozyme (or whatever it was)? Does dust necessarily carry a
lot of pathogens?

I have no particular preference for "when" human features arise. In
fact, I think I tend to go the opposite way, and assume they arose fairly
early, until someone can come up with a good reason otherwise.

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