Re: Brains size and sweat

William T. Yates (
Wed, 08 Jan 1997 20:12:03 -0800

I've been working up a sweat trying to follow this discussion, and I
think my brain is overheating!

A question: Man may sweat profusely, but isn't the cooling effect
dependent on how much of this water is actually evaporated from the
skin? That's the way the heat energy is removed, by using it to
dissociate the liquid water molecules into water vapor. Agreed, the more
you sweat, the more water is available for evaporation, but I wonder, is
there an optimum rate for sweating where you achieve the maximum cooling
effect with the minimum loss of bodiy water? The point being that merely
the rate of sweat production is not the whole story in the cooling
effect. Much sweat simply drops off.

And re the Watusi... don't forget the Pygmies! Africans come in varied
body styles!

Just wondering...
--Bill Yates

Glenn Morton wrote:
> > To continue an on-going discussion:
> >
> >(1) The unanimous consensus of the books (about 12 I read) was that
> >sweating constitutes on 25% of the cooling system in human beings;
> >60% of heat loss in humans is from radiation.
> >
> If this is an average, over most of the time, then I have no doubt about it.
> At temperatures above 80 F or so, the rate of heat loss from the body by
> radiation is insufficient to relieve the body of enough heat. At 90 F humans
> sweat fairly easily and by 98.9 radiation removes almost no heat. Sweat must
> remove nearly all of it.
> This is a size effect. Larger animals have a smaller surface area/mass ratio.
> This is why Eskimo bodies are short and stout--that shape minimizes surface
> area and retains heat. African bodies, like the Watusi, are long and lean,
> maximizing surface area and minimizing heat retention.
> glenn
> Foundation,Fall and Flood

--Bill Yates