Re: Holloway/Morgan

Peter Card (
25 Jul 1995 12:47:38 +0100 (Phil Nicholls) writes:

[stuff deleted]

>4. Large bodied primates, when subjected to heat stress, produce
> eccrine sweat though not in amounts that would provide
> significant cooling.

>Large bodies primates for the most part are not subjected to intense
>heat stress. Those that are have adapted via behavior. They are
>inactive during the hottest parts of the day and rest in the shade.

I read this and it struck me, probably not very originally, that
aquatic creatures in general are not subject to intense heat
stress. Flexible cooling via eccrine sweating and the associated
neural mechanisms would be selected for where the organism experienced
heat stress, and not in an aquatic environment. In fact the whole
sweaty argument seems to work against the AAH.

I am probably restating part of the "radiator" hypothesis, but
wouldn't an efficient and flexible cooling mechanism be part of the
recipe for an effective cursorial predator on the savannah, such as a
modern human. I have read that a fit human can run longer and further
than most animals, allowing them to run down prey. There are easier
ways to catch deer, or antelope, or whatever, for modern humans, armed
with weapons and language, but it is plausible that the unusual human
cooling system was originally selected for by a particular mode of
predation, and that in turn took enabled large brain size.

"The avalanche has already begun, it is too late for the pebbles to vote"

The above article is the personal view of the poster and should not be
considered as an official comment from the JET Joint Undertaking