Death of a hypothesis

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Elaine Morgan

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May 8, 1996, 3:00:00 AM5/8/96
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The one facet of the case in "Scars" that I feel has been seriosuly
dented is my personal speculation that Homo's sweat and tears may
originally have evolved to excrete salt, even though they are no longer
hypotonic. I've already conceded in the case of tears that the case
does not stand up.That has had a domino effect since I thought the two
were possibly connected. I withdraw on the sweat also.
It remains as true as ever that we have become for some reason the
leakiest animals in the world, and this is extremely unlikely to have
been a response to arid savanna conditions - but that has become largely
irrelevant since the savanna is also in shtook.

My beautiful hypothesis was slain by three ugly facts - the
eccrine-sweating patas (courtesy of pnich), the fact that our erratic
respons to salt imbalance applies equally to a number of terrestrial
mammals (courtesy of Jdm) and the fact that in seals, unlike in marine
iguanas, if you feed them with salt water it does not make them cry
(courtesy of Elaine Morgan)

I believe the case for an aquatic phase in our evolution is strong
enough to stand without that one particular speculation. Recanting it
does have one interesting consequence. When I now hypothesise an aquatic
phase, I have no anatomical pointers to where it happened. I still tend
to lean towards the Afar area, simply because it would best explain a
period of geographical isolation which would have speeded divergence.
But a freshwater site like Turkana would now also be in the running.

So to coin a phrase we are now back to square one on questions like why
does the gorilla have so many eccrine glands when it does not use them
for thermoregulation? Here's a tentative (non-aquatic) suggestion. N.B,
I'm not claiming this as a Theory, or a Hypothesis, or anything like
that. Just wondering, okay? I'm allowed to wonder?

According to Gary Schwartz ( and, much earlier, to Schultz) hair density
in primates decreases allometrically with size, as if the same number of
follicles were spaced out to cover greater areas of skin. I believe it
is also said to be true (can anyone verify?) that skin thickness
increases with size.

Now in small mammals with thin skin some moisture continually seeps out
through it without benefit of skin glands; enough to keep the skin moist
and supple. Perhaps it can't get out through the thicker skin of the
gorilla; and the apocrine glands (attached to the hairs) are too wide
apart to prevent the skin from becoming dry and stiff. So eccrines
sprang up in between the apocrines to prevent that happening. That would
make sense of why there are more of them in apes than in monkeys -
because apes are bigger.

Montagna put up a powerful case for believing that they first evolved
for some reason other than thermoregulation and were co-opted into that
function later. That would figure too. The egregious patas, which puts a
spanner in the works of so many theorists on both sides of the (aquatic)
fence, does not necessarily invalidate this one. Apparently it does not
succeed in sweating so successfully by having very large numbers of
eccrine glands, but by increasing the output of the glands it does
possess. Elizondo in his famous patas paper does not give an estimate of
the number of eccrines per square cm. in the patas, but he reports an
estimate of 136 p.s.cm for the rhesus, which also sweats some. And he
gives no indiction that the figure differs dramatically in the patas.
But the number of patas hair follicles (and hence of apocrine glands)
was given by Schultz as around 1546 p.s.cm. So the eccrines seem
probably a small percentage numerically even though they can become
hyperactive.

I don't suppose anybody else finds that interesting, but I do. Even homo
fits the pattern to the extent that our immensely larger number of
eccrines could be simply a consequence, originally, of the loss of body
hair. And that in turn was a consequence of .... well we won't go into
that! We have covered the ground too often.

Can any kind scientist please give me a definition of the word
"cholinergic

Elaine

Elaine.


msd...@cbdcom.apgea.army.mil

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May 10, 1996, 3:00:00 AM5/10/96
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Gerrit Hanenburg

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May 10, 1996, 3:00:00 AM5/10/96
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Elaine Morgan <ela...@desco.demon.co.uk> wrote:

>It remains as true as ever that we have become for some reason the
>leakiest animals in the world, and this is extremely unlikely to have
>been a response to arid savanna conditions - but that has become largely
>irrelevant since the savanna is also in shtook.

Fact remains that profuse eccrine sweating *is* a physiological response to
thermal stress,and as such is most parsimoniously explained as an
adaptation to an environment where there is considerable thermal stress and
where humidity is low enough to allow for cutaneous evaporative cooling.
The fossil data in the form of the nearly complete skeleton of KNM-WT 15000
and its paleoenvironment indirectly indicate that eccrine sweating probably
already had a mainly thermoregulatory function in early Homo erectus.

Gerrit

Phil Nicholls

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May 11, 1996, 3:00:00 AM5/11/96
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Elaine Morgan (Elaine Morgan <ela...@desco.demon.co.uk>) writes:


>Can any kind scientist please give me a definition of the word
>"cholinergic

Cholinergic refers to the neurotransmitter acetylcholine. Cholinergic
neurons are those that use acetylcholine as a neurotransmitter or are
believed to use acetylcholine as a neurotransmitter because of a
positive stain for acetylcholinesterase, the enzyme that degrades
acetylcholine.
.
Acetylcholine is used by neurons of the parasympathetic division of
the autonomic nervous system and associated with localized action in
discrete regions as apposed to the mass reaction characteristic of the
sympathetic nervous system. Eccrine sweat glands are innervated by
cholinergic neurons while apocine glands are innervated by
noradrenergics (ie, neurons using noradrenalin [norepinephrine]).

Phil Nicholls pn...@globalone.net
"To ask a question you must first know most of the answer"
-Robert Sheckley


Paul Crowley

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May 14, 1996, 3:00:00 AM5/14/96
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In article <Dr7M...@inter.NL.net>
ghan...@inter.NL.net "Gerrit Hanenburg" writes:

> Fact remains that profuse eccrine sweating *is* a physiological response to
> thermal stress,and as such is most parsimoniously explained as an
> adaptation to an environment where there is considerable thermal stress and
> where humidity is low enough to allow for cutaneous evaporative cooling.

^^^^^^^^^^^^^^^^^^^^^^
It is a common assumption that sweating evolved for low-humidity
environments. But is it true? The intensity of the sweating
response in h.s.s. is universally remarked upon; it far exceeds
that of any other animal. But if we evolved for an environment
where relatively little sweating was adequate for cooling purposes,
why did we acquire such an extreme ability?

This extreme ability would have been necessary, even in those
environments, had early hominids survived by regular pursuit
of fast animals on the savannah - the hunting hypothesis. Since
this is now fairly dead, I suggest that the sweating hypothesis
that went along with it should be re-evaluated. One problem about
heavy sweating on high savannah is that there is little water
there, and if one thing is certain in the story of human evolution
it is that, when this response was evolved, hominids had immediate
and constant supplies of water

I suggest that the h.s.s. unique sweating response evolved in
those areas where it was needed most - ones of *high* humidity.
These would be at or close to sea level. Also they would
generally have a much better water supply.

This may feel counter-intuitive. Generally, we do our best to
avoid stressful situations. We all feel more comfortable on
higher ground, where we don't have to pour out gallons of sweat
to survive. But surely such an ability would not have evolved
unless our ancestors were in an environment where it was
essential? I suggest that it was there that they found food
and a refuge from predators; but a major problem was heat
stress. Intense sweating was the main response.

Paul.

Alex Duncan

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May 14, 1996, 3:00:00 AM5/14/96
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In article <832065...@crowleyp.demon.co.uk> Paul Crowley,
Pa...@crowleyp.demon.co.uk writes:

>I suggest that the h.s.s. unique sweating response evolved in
>those areas where it was needed most - ones of *high* humidity.
>These would be at or close to sea level. Also they would
>generally have a much better water supply.

Sweating is NOT an effective cooling mechanism in a high humidity
environment. For sweating to operate to cool the body, the sweat has to
evaporate.

People who are acclimated to high humidity environments don't sweat
nearly as much there as people who are "visiting" from low humidity
environments.

Darn.

Alexander S. Duncan
Dept. of Anthropology
University of Texas at Austin
Austin, TX 78712-1086
(512) 471-4206
adu...@mail.utexas.edu

David L Burkhead

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May 14, 1996, 3:00:00 AM5/14/96
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In article <4na26l$t...@geraldo.cc.utexas.edu> Alex Duncan <adu...@mail.utexas.edu> writes:
>In article <832065...@crowleyp.demon.co.uk> Paul Crowley,
>Pa...@crowleyp.demon.co.uk writes:
>
>>I suggest that the h.s.s. unique sweating response evolved in
>>those areas where it was needed most - ones of *high* humidity.
>>These would be at or close to sea level. Also they would
>>generally have a much better water supply.
>
>Sweating is NOT an effective cooling mechanism in a high humidity
>environment. For sweating to operate to cool the body, the sweat has to
>evaporate.

Is there a _Physicist_ in the house? Oh, wait. I'm one. Alex
is essentially correct. Sweat cools by evaporation. Water takes a
great deal of heat to change from liquid to gas, and that energy comes
from heat.

The rate at which heat is carried away is directly proportional
to the rate of sweat evaporation. That rate is determined by two
things: temperature of the liquid and the partial pressure of water
vapor in the surroundings (humitidy). The temperature of the liquid
sweat will be, to a close approximation, skin temperature. That
remains within fairly narrow bounds over much of the body (as I
understand it--I'm not a biologist), so it can be treated as
essentially constant. That means that partial pressure of water vapor
is the driving factor in the rate at which heat can be lost through
sweating. I.e. low humidity means you can shed more heat through
sweat in a given period of time.

Now, under normal circumstances, the latent heat of evaporation
of water is _very_ close to constant. That means that regardless of
humidity, they will have to evaporate the same amount of water to
eliminate the same amount of heat. This is more difficult to to in
high humidities since evaporation rates are lower.

This also leads to the surprise people who are unfamiliar with
really dry climates encounter when they experience hot, dry places.
They "stop sweating." What happens is that the water evaporates as
fast as it is released, leaving no liquid on the surface to be
seen or felt. This results in the absolute most efficiency possibly
from evaporative cooling. There is no loss of liquid dripping off
the body (where it's evaporation cannot be used to cool the body).
It's the best you can do if your goal is to keep body temperature
constant. Other animals that I am familiar with that retain water
better than do humans, do so by letting body temperature rise during
the day and using a form of "spot cooling" to keep the brain cool.
Alternately, they seek shelter from the heat and only come out when
it's cooler. Humans function actively during higher temperature
periods than many animals, including those evolved in regions with
high temperatures, and don't have the equipment for the "spot
cooling" so that's not an option.

Oh, one more thing. I forgot to mention above another factor in
sweat evaporation rates: amount of dissolved solids. The more solids
that are dissolved in water, the slower it evaporates. Thus, were
sweat to be more concentrated in salts than it is, it would be less
efficient as a cooling mechanism. I don't know the case for sweat in
general, but if it varies much in creature to creature those with less
saline sweat would, from basic physical principles and other things
being equal, find themselves better able to remain cool than those
with more saline sweat.

David L. Burkhead
r3d...@dax.cc.uakron.edu
FAX: 330-253-4490

Thomas Clarke

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May 14, 1996, 3:00:00 AM5/14/96
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In article <832065...@crowleyp.demon.co.uk> Paul Crowley
<Pa...@crowleyp.demon.co.uk> writes:

> ... a major problem was heat

> stress. Intense sweating was the main response.

Don't forget the possibility that copious sweating also served
to rid the hominid of excess salt in its diet.
Neat solution by evolution, that. Deal with heat stress and get
rid of excess salt without having to change the kidneys.

Tom Clarke


Paul Crowley

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May 14, 1996, 3:00:00 AM5/14/96
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In article <4na26l$t...@geraldo.cc.utexas.edu>
adu...@mail.utexas.edu "Alex Duncan" writes:

> Pa...@crowleyp.demon.co.uk writes:
> >I suggest that the h.s.s. unique sweating response evolved in
> >those areas where it was needed most - ones of *high* humidity.
> >These would be at or close to sea level. Also they would
> >generally have a much better water supply.
>
> Sweating is NOT an effective cooling mechanism in a high humidity
> environment. For sweating to operate to cool the body, the sweat has to
> evaporate.

Sweating is not AS effective a cooling mechanism in a high humidity
environment. That is my point. If h.s.s. had evolved in a low
humidity environment it would not have needed its present mechanism,
unless as per the hunting hypothesis it engaged in intense activity
under the midday sun (and also carried a water bottle around).

If h.s.s had to survive in a high humidity environment, it would
have needed whatever cooling mechanism it could manage. What
else is there? It's also another compelling reason for the loss
of hair; this reason would not apply on higher ground. OK, the
sweat does not evaporate so quickly. You'd have a lot of liquid
all over your body, some of which would just drip to the ground
with little, if any, cooling effect. The absence of any mechanism
which restricts ineffective over-sweating is most remarkable.
It speaks for plentiful supplies of fresh water.

> People who are acclimated to high humidity environments don't sweat
> nearly as much there as people who are "visiting" from low humidity
> environments.

I don't get your point here. People acclimatise to their local
environment. So . . . ?

Paul.

David L Burkhead

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May 14, 1996, 3:00:00 AM5/14/96
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And this particularly egregious bit of speculation has been shot
so full of holes that it resembles an old, rusted-out, screen door.

Since the kidneys function is not just to get rid of excess salt
(actually, a mix of different salts--not just sodium chloride), but to
maintain salt balance (proper ratios of those different salts), and
since the sweat glands _alters_ the salt balance, the kidneys have to
work harder to restore proper balance.

If, for instance, the sweat glands excrete more potassium salts
than sodium salts (illustrative example, not meant to reflect which is
actually preferentially excreted), the body fluids experience an
increase of relative concentration of sodium. The kidneys, then, have
to not only dump salt, but preferentially dump the sodium while
retaining more potassium. This requires more work on the kidneys'
part.

Gerrit Hanenburg

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May 14, 1996, 3:00:00 AM5/14/96
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Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:

>One problem about heavy sweating on high savannah is that there is little water
>there, and if one thing is certain in the story of human evolution
>it is that, when this response was evolved, hominids had immediate
>and constant supplies of water

"immediate" does seem to be a little exaggerated,but
I do agree that it is unlikely that humans evolved eccrine sweating in an
environment where they had no regular access to fresh water.
River,lake,waterhole,marsh,any of those will do.

>I suggest that the h.s.s. unique sweating response evolved in
>those areas where it was needed most - ones of *high* humidity.
>These would be at or close to sea level. Also they would
>generally have a much better water supply.

The cooling function of sweating decreases in environments with a high
relative humidity.If you can't lose heat by means of evaporative cooling
what use is sweating? Increased sweating won't help you if it doesn't
evaporate.

>This may feel counter-intuitive. Generally, we do our best to
>avoid stressful situations. We all feel more comfortable on
>higher ground, where we don't have to pour out gallons of sweat
>to survive. But surely such an ability would not have evolved
>unless our ancestors were in an environment where it was
>essential?

Probably an environment where they were subject to considerable thermal
stress and with a low enough relative humidity to make evaporative cooling
work.

>I suggest that it was there that they found food

>and a refuge from predators; but a major problem was heat

>stress. Intense sweating was the main response.

Exactly! ;-)

Gerrit.


Alex Duncan

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May 15, 1996, 3:00:00 AM5/15/96
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In article <832100...@crowleyp.demon.co.uk> Paul Crowley,
Pa...@crowleyp.demon.co.uk writes:

>Sweating is not AS effective a cooling mechanism in a high humidity
>environment. That is my point. If h.s.s. had evolved in a low
>humidity environment it would not have needed its present mechanism,
>unless as per the hunting hypothesis it engaged in intense activity
>under the midday sun (and also carried a water bottle around).

So, you're saying that in an environment where evaporative cooling would
be very effective, we don't need evaporative cooling, because...?

But in an environment where evaporative cooling doesn't work well at all,
it would be the best choice for thermoregulation?

Maybe you better explain it again.

You would think just being in the cool, refreshing waters of the Red Sea
would provide plenty of cooling. Or, to extend your argument: maybe
since evaporative cooling doesn't work AT ALL when we're in the water,
and staying warm would be the major challenge in any case, our ancestors
would necessarily have evolved a human-like sweating capacity. Oooh --
now I get it. We were in the water sweating profusely as a means of
generating heat. If the sweat glands were working so heavily as to
generate heat, then significant amounts of heat would've been generated.

It's all so simple! Why didn't I see it before?

The only time sweat would be necessary for cooling would be on the long
march to the burial grounds at Lake Turkana. (Just out of curiosity --
do you suppose the treks to the burial grounds can be likened to the
lemming death marches?)

Paul Crowley

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May 15, 1996, 3:00:00 AM5/15/96
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In article <4nbdro$1...@geraldo.cc.utexas.edu>
adu...@mail.utexas.edu "Alex Duncan" writes:

> In article <832100...@crowleyp.demon.co.uk> Paul Crowley,
> Pa...@crowleyp.demon.co.uk writes:
>
> >Sweating is not AS effective a cooling mechanism in a high humidity
> >environment. That is my point. If h.s.s. had evolved in a low
> >humidity environment it would not have needed its present mechanism,
> >unless as per the hunting hypothesis it engaged in intense activity
> >under the midday sun (and also carried a water bottle around).
>
> So, you're saying that in an environment where evaporative cooling would
> be very effective, we don't need evaporative cooling, because...?
>
> But in an environment where evaporative cooling doesn't work well at all,
> it would be the best choice for thermoregulation?

It would be the best choice because it was the only one readily
available. Given the plentiful water supply, it was good enough.
What alternatives would you suggest were possible?

Paul.

Elaine Morgan

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May 15, 1996, 3:00:00 AM5/15/96
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In article <Dr7M...@inter.NL.net> ghan...@inter.NL.net wrote...


> Fact remains that profuse eccrine sweating *is* a physiological response to
> thermal stress

Of course. That has never been in dispute.

,and as such is most parsimoniously explained as an
> adaptation to an environment where there is considerable thermal stress and
> where humidity is low enough to allow for cutaneous evaporative cooling.

What primate-skin specialists question is whether our millions of
non-volar eccrines originally evolved for that purpose. If you say yes,
you have a problem. The only animals with even half that number of
eccrines are the forest-dwelling gorillas and chimps in which they do
*not* function for thermoregulation. You would have to postulate that
the gorilla and chimp also once lived on the savanna - an environment
where there is considerable thermal stress and low humidity - and then
returned to the forest where the glands gradually became non-functional.
Do you really think that?

> The fossil data in the form of the nearly complete skeleton of KNM-WT 15000
> and its paleoenvironment indirectly indicate that eccrine sweating probably
> already had a mainly thermoregulatory function in early Homo erectus.
>

This too has never been in dispute. By the time of homo erectus it seems
clear that the hominids were running around on the savanna. I suspect
that their physiological adaptations prevented them from wandering as
freely far away from water sources as some other savanna species, but I
see no reason to doubt that they were using sweat-cooling by then.

Elaine
>
>


Gerrit Hanenburg

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May 15, 1996, 3:00:00 AM5/15/96
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Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:

>> But in an environment where evaporative cooling doesn't work well at all,
>> it would be the best choice for thermoregulation?

>It would be the best choice because it was the only one readily
>available. Given the plentiful water supply, it was good enough.
>What alternatives would you suggest were possible?

Small overall size and relative long limbs (high surface to volume ratio)

Gerrit.


Gerrit Hanenburg

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May 15, 1996, 3:00:00 AM5/15/96
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Elaine Morgan <ela...@desco.demon.co.uk> wrote:

>What primate-skin specialists question is whether our millions of
>non-volar eccrines originally evolved for that purpose. If you say yes,
>you have a problem. The only animals with even half that number of
>eccrines are the forest-dwelling gorillas and chimps in which they do
>*not* function for thermoregulation.

Well,I doubt *that* assumption.
I recall George Schaller reporting:"I have observed animals lie in the direct
sun for more than two hours,with beads of sweat forming on their upper lip and
rivulets of it running down the chest."
(The Mountain Gorilla:Ecology and Behaviour.University of Chicago Press,Midway
reprint ed.1988,p.295)



>You would have to postulate that the gorilla and chimp also once lived on the savanna - an environment
>where there is considerable thermal stress and low humidity - and then
>returned to the forest where the glands gradually became non-functional.
>Do you really think that?

No,but I doubt that the assumption that the eccrine sweatglands in Gorillas and
Chimps are entirely non-functional.

Gerrit.


Phil Nicholls

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May 16, 1996, 3:00:00 AM5/16/96
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Gerrit Hanenburg (ghan...@inter.NL.net (Gerrit Hanenburg)) writes:

>Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:

>>One problem about heavy sweating on high savannah is that there is little water
>>there, and if one thing is certain in the story of human evolution
>>it is that, when this response was evolved, hominids had immediate
>>and constant supplies of water

>"immediate" does seem to be a little exaggerated,but
>I do agree that it is unlikely that humans evolved eccrine sweating in an
>environment where they had no regular access to fresh water.
>River,lake,waterhole,marsh,any of those will do.

Humans have the capacity to undergo voluntary dehydration. This means
that then can incur a temporary negative water balance by withdrawing
free circulating water from the gut (up to 2 liters). The trick is
that it must be replaced at night. This provides a buffer against
dehydration during the day.

We can assume that early hominids lived near wateholes or rivers and
that like other mammals they engaged in behaviors to minimize heat
stress.

Paul Crowley

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May 16, 1996, 3:00:00 AM5/16/96
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In article <DrGvK...@inter.NL.net>
ghan...@inter.NL.net "Gerrit Hanenburg" writes:

> Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:
> >> But in an environment where evaporative cooling doesn't work well at all,
> >> it would be the best choice for thermoregulation?
>
> >It would be the best choice because it was the only one readily
> >available. Given the plentiful water supply, it was good enough.
> >What alternatives would you suggest were possible?
>
> Small overall size and relative long limbs (high surface to volume ratio)

And what was Lucy? - About as small (I guess) as a hominid can get.
OK, male afarensis were large, but the size of males is relatively
unimportant. They probably died well before the females. From a
breeding point of view, mature females could outnumber mature males
by ten to one, although I'd say that they proportion was probably
closer to two to one or three to one.

Paul.

Phil Nicholls

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May 17, 1996, 3:00:00 AM5/17/96
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Paul Crowley (Paul Crowley <Pa...@crowleyp.demon.co.uk>) writes:

>I suggest that the h.s.s. unique sweating response evolved in
>those areas where it was needed most - ones of *high* humidity.
>These would be at or close to sea level. Also they would
>generally have a much better water supply.

>This may feel counter-intuitive. Generally, we do our best to

>avoid stressful situations. We all feel more comfortable on
>higher ground, where we don't have to pour out gallons of sweat
>to survive. But surely such an ability would not have evolved
>unless our ancestors were in an environment where it was

>essential? I suggest that it was there that they found food

>and a refuge from predators; but a major problem was heat
>stress. Intense sweating was the main response.

As I am sure several others have pointed out by now, you really blew
this one. Sweating does work particularly well when humidity is
high, Paul. That's a basic fact of physiology.

You seem to see yourself as someone who can cut through the bullshit
of paleoanthropology and offer a new perspective. How do you hope to
do this when you can't seem to get your facts straight?

By the way, did you ever respond to the point ot Zihlman and Tanner?

Paul Crowley

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May 17, 1996, 3:00:00 AM5/17/96
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In article <4nasvl$1...@kira.cc.uakron.edu>

r3d...@dax.cc.uakron.edu "David L Burkhead " writes:

> Since the kidneys function is not just to get rid of excess salt
> (actually, a mix of different salts--not just sodium chloride), but to
> maintain salt balance (proper ratios of those different salts), and
> since the sweat glands _alters_ the salt balance, the kidneys have to
> work harder to restore proper balance.

I know you've said this before, but I never followed the logic then
either. Please bear with me but my understanding is that the kidneys
adjust the balance in the blood plasma to what is desirable. If they
find too much sodium, they excrete that; if too much potassium, or
urea or whatever, they excrete that. So long as the urine is not
over-concentrated, they will have no problems with this operation.
If large amounts of salt are eaten, the "work" of the kidneys goes
up. This will not create any problems unless the quantities are
excessive or not enough liquid is consumed to carry it away.

I cannot see how sweating increases the load on the kidneys. If
it disposes of excess salt, surely the kidneys will have less to
do? If, say, sweating reduces sodium to a low level, and some
potassium/sodium balance is desirable, then the kidney has to
excrete more potassium. A load on the kidneys will come from large
quantities of excess salts. Adjustments at a low level must be
part of their normal activity and could hardly constitute any
additional imposition.

IOW, when you say "the kidneys have to work harder" are you saying
that they get hotter, or exceed their capacity, or what?

Paul.

Alex Duncan

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May 18, 1996, 3:00:00 AM5/18/96
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Earlier I wrote:
>Sweating is NOT an effective cooling mechanism in a high humidity
>environment. For sweating to operate to cool the body, the sweat has to
>evaporate.
>
>People who are acclimated to high humidity environments don't sweat
>nearly as much there as people who are "visiting" from low humidity
>environments.

Since then I've done some checking (in one of those "book" things you may
have heard about), and discovered that I was incorrect. When a person
acclimatized to low humidity is moved to a high humidity environment,
over a period of several days the rate of sweat production increases.
The study did not address sweat rates between "native" and "non-native"
inhabitants of high humidity environments.

Phillip Bigelow

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May 19, 1996, 3:00:00 AM5/19/96
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Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:
>In article <4nasvl$1...@kira.cc.uakron.edu>
> r3d...@dax.cc.uakron.edu "David L Burkhead " writes:
>
>> Since the kidneys function is not just to get rid of excess salt
>> (actually, a mix of different salts--not just sodium chloride), but to
>> maintain salt balance (proper ratios of those different salts), and
>> since the sweat glands _alters_ the salt balance, the kidneys have to
>> work harder to restore proper balance.
>
>I know you've said this before, but I never followed the logic then
>either. Please bear with me but my understanding is that the kidneys
>adjust the balance in the blood plasma to what is desirable. If they
>find too much sodium, they excrete that; if too much potassium, or
>urea or whatever, they excrete that. So long as the urine is not
>over-concentrated, they will have no problems with this operation.
>If large amounts of salt are eaten, the "work" of the kidneys goes
>up. This will not create any problems unless the quantities are
>excessive or not enough liquid is consumed to carry it away.

I have stayed out of this discussion since I have been in this newsgroup
for two reasons: 1) I don't know much about the subject, and 2) what I do
know about the subject tells me that Elaine's conclusions on this are
probably over-blown, and probably not particularly relevant to aquatic
adaptation in the first place.

Here is my thesis in a nut-shell:
If large quantities of salt(s) are ingested, why don't we sweat more,
even if we are *not* over-heated, or even if we are *not* exerting
ourselves?
This whole salt-ballance and salt-serum concentration debate is getting
nowhere. There is no clear-cut *direct* relationship (cause-and-effect
relationship) between salt ballance in the plasma and the amount of sweat
we excrete. On the contrary, we sweat either when we are over-heated,
and/or when we exert, or when we are emotionally-excited.
In a cool-temperature environment, when a calm at-rest individual
ingests excessive salt, the kidneys do the work. Not the sweat glands.
Period. Case closed. The blood salt-ballance issue, although
scientifically well-understood, is not relevant to this
particular discussion.
<pb>

Paul Crowley

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May 19, 1996, 3:00:00 AM5/19/96
to

In article <4nlt8t$i...@ra.cc.wwu.edu>
phi...@lubricant.free.org "Phillip Bigelow" writes:

> If large quantities of salt(s) are ingested, why don't we sweat more,
> even if we are *not* over-heated, or even if we are *not* exerting
> ourselves?

An AAT version would say that consumption of relatively large amounts
of salt (say 20 g per day) only occurred when the hominids were at
sea level in tropical climes. So sweating was automatically tied
to consumption; no biological mechanism was needed.

> This whole salt-ballance and salt-serum concentration debate is getting
> nowhere. There is no clear-cut *direct* relationship (cause-and-effect
> relationship) between salt ballance in the plasma and the amount of sweat
> we excrete. On the contrary, we sweat either when we are over-heated,
> and/or when we exert, or when we are emotionally-excited.

If we sweat the same (say 5 litres) each day then the more salt we eat
the more we will excrete through sweating. Isn't this correct?

> In a cool-temperature environment, when a calm at-rest individual
> ingests excessive salt, the kidneys do the work. Not the sweat glands.
> Period. Case closed. The blood salt-ballance issue, although
> scientifically well-understood, is not relevant to this
> particular discussion.

But our evolution was not in a cool-temperature environment. It
was in one where we sweated a great deal. At least that's what our
anatomy indicates.

I agree that not a great deal appears to hang on it. Our kidneys
seem quite well able to cope with 20g or thereabouts of salt -
given a good supply of water. But sweating needs an explanation;
it would also have needed a good supply of water. When you sweat a
lot you don't pass much urine. The excretion of salt through the
skin would have been a necessary feature (or adaptation?).

Paul.


chris brochu

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May 20, 1996, 3:00:00 AM5/20/96
to

In article <832543...@crowleyp.demon.co.uk> Paul Crowley,

Pa...@crowleyp.demon.co.uk writes:
>If we sweat the same (say 5 litres) each day then the more salt we eat
>the more we will excrete through sweating. Isn't this correct?
>

No. Sweat nearly always has the same composition, regardless of how much
salt you've eaten.


chris

Phil Nicholls

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May 20, 1996, 3:00:00 AM5/20/96
to

Thomas Clarke (cla...@acme.ist.ucf.edu (Thomas Clarke)) writes:

>In article <832065...@crowleyp.demon.co.uk> Paul Crowley
><Pa...@crowleyp.demon.co.uk> writes:

>> ... a major problem was heat

>> stress. Intense sweating was the main response.

>Don't forget the possibility that copious sweating also served


>to rid the hominid of excess salt in its diet.
>Neat solution by evolution, that. Deal with heat stress and get
>rid of excess salt without having to change the kidneys.

Unless you propose that the physiology of sweating differs today from
what is observed in humans and in other animals that sweat then this
is not likely. Too much water is lost due to the hypotonic nature of
sweat. Besides, the kidneys do a very good job of elimating excess
salt.

If you suggest that sweat was hypertonic at one time then you are
moving into the never-never land of untestable assertions.

Jim Moore

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May 20, 1996, 3:00:00 AM5/20/96
to

In reply to a message by Paul Crowley on 19-May-96 22:05:24:


>In article <4nlt8t$i...@ra.cc.wwu.edu>
> phi...@lubricant.free.org "Phillip Bigelow" writes:

>> If large quantities of salt(s) are ingested, why don't we sweat more,
>> even if we are *not* over-heated, or even if we are *not* exerting
>> ourselves?

>An AAT version would say that consumption of relatively large amounts
>of salt (say 20 g per day) only occurred when the hominids were at
>sea level in tropical climes. So sweating was automatically tied
>to consumption; no biological mechanism was needed.

But sweating doesn't happen as a consequence of consumption of salt, or
water, or anything short of chili peppers. If it were ever a
salt-excretion mechanism we reasonably would expect it to do so.
Salt-excretion mechanisms, such as kidneys in mammals and salt glands
in reptiles and birds, perform as a result of that stimulus, as indeed
they must to do the job.

Jim Moore e-mail:jimm...@inforamp.net


Jim Moore

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May 20, 1996, 3:00:00 AM5/20/96
to

In reply to a message by chris brochu on 20-May-96 01:34:59:

Sweat does vary in salt content, as a result of the fluid being pumped
against a gradient, but for the myriad reasons that obviously haven't
sunk in to some skulls, it isn't a salt excretion mechanism. If
anything -- as has been pointed out -- it acts to conserve salt rather
than eliminate it. This also fits with our salt appetite, a feature
which *does not* fit with a marine background.

Jim Moore e-mail:jimm...@inforamp.net


Thomas Clarke

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May 21, 1996, 3:00:00 AM5/21/96
to

In article <4noi83$j...@geraldo.cc.utexas.edu> chris brochu
<ga...@mail.utexas.edu> writes:
> In article <832543...@crowleyp.demon.co.uk> Paul Crowley,
> Pa...@crowleyp.demon.co.uk writes:
> >If we sweat the same (say 5 litres) each day then the more salt we eat
> >the more we will excrete through sweating. Isn't this correct?

> No. Sweat nearly always has the same composition, regardless of how much
> salt you've eaten.

I believe you are mistaken. I found contradictory data in
Kuno, Yas (1956); _Human Perspiration_; Charles C. Thomas Publisher,
Springfield, IL; 416pp.

In the chapter on the Chemistry of Sweat there is
a discussion of the effect of salt intake on the rate of sweating.
"In the experiments of Sengoku (1941), which were made on three
subjects, salt intake was entirely stopped for six to seven days while
the subjects were made to sweat profusely once a day. The chloride
concentration of sweat measured during maximal sweating fell to 1/8 to
1/10 of the level before the salt deficiency while the fall of cloride
in the blood was not remarkable. Lock, Talbot and Jones and Worcester
(1951) observed the effect of varying the intake of sodium chloride and
potassium salts. Two subjects were given diets containing very large
amounts of sodium chloride for ten days and found that the chloride-
index above mentioned rose considerably. " (page 230, a figure from
Lock et al is reproduced on page 228 and a change from 5 gms or sodium
per square meter of body surface per day to 25 grams/m^2/day seems
to raise the salt concentration of the sweat also by a factor of 5)

Note that chloride and salt are essentially identical: "Sodium in
sweat is all combined with chlorine ... sodium in sweat is almost
equimolar with chlorine..." (page 231).

Tom Clarke

Paul Crowley

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May 21, 1996, 3:00:00 AM5/21/96
to

In article <843.6714...@inforamp.net>
jimm...@inforamp.net "Jim Moore" writes:

> Sweat does vary in salt content, as a result of the fluid being pumped
> against a gradient, but for the myriad reasons that obviously haven't
> sunk in to some skulls, it isn't a salt excretion mechanism.

You drink fresh water; you sweat salty water; ergo, you lose salt.

> If anything -- as has been pointed out -- it acts to conserve salt
> rather than eliminate it.

How does losing salt conserve it?

> This also fits with our salt appetite, a feature
> which *does not* fit with a marine background.

Why? The LCA almost certainly had a salt appetite. We then
adapted to a particularly salty diet and acquired even more of
a taste for the stuff. Has anyone done experiments on the
amount of salt chimps (or other primates) would eat given a
choice between equivalent low-salt and high-salt foods? It
could be done in any zoo. If the figure worked out to
significantly less than the human one, it would be good support
for the theory of a high consumption of seafood in our recent
evolutionary history (and maybe for the AAT as well).

Given the salt appetite of chimps, it is very, very suprising
that they don't forage for fresh-water molluscs. It's quite
likely that that was the first proto-hominid behaviour to be
adopted, leading in time to foraging on the seashore, leading
then to bipedalism.

BTW I see that the normal adult consumption is 9 grams a day,
increasing hypertension and heart disease. I bet people who
sweat a lot have fewer such problems. Exercise is known to be
beneficial; perhaps the sweating is an important element.
Research should be done on regular but non-energetic sweaters,
such as those with sedentary occupations in hot areas. It
would be easy enough to get historical records and see how
many died of heart problems as compared with other comparable
groups. Bus drivers in tropical cities as against those in
temperate ones, might be a possibility. Again the
introduction of air-conditioning in buses (or generally)
should increase, or have increased, hypertension. Records
from Greyhound might tell a story.

Paul.

Jim Moore

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May 21, 1996, 3:00:00 AM5/21/96
to

In reply to a message by Paul Crowley on 21-May-96 20:35:04:


>In article <843.6714...@inforamp.net>
> jimm...@inforamp.net "Jim Moore" writes:

>> Sweat does vary in salt content, as a result of the fluid being pumped
>> against a gradient, but for the myriad reasons that obviously haven't
>> sunk in to some skulls, it isn't a salt excretion mechanism.

>You drink fresh water; you sweat salty water; ergo, you lose salt.

As has been explained here many many times in ever simpler language,
what you describe is an uncontrolled process that entails severe health
risks; it is not an excretion mechanism, which by its nature must be
controlled, and which do not offer severe health risks in normal use.
Not to mention that for a creature in a saltwater environment, this
would also require massive amounts of fresh water.

>> If anything -- as has been pointed out -- it acts to conserve salt
>> rather than eliminate it.

>How does losing salt conserve it?

As has been explained here many many times in ever simpler language,
when sweating you lose far more water than salt, and salt is in fact
reabsorbed into the plasma when sweating. (It's sorta like having a
strainer with holes that stop most of a water/solid mixture.) This
is not the action of an excretion mechanism, but it is the action of
a conservation mechanism.

>> This also fits with our salt appetite, a feature
>> which *does not* fit with a marine background.

>Why? The LCA almost certainly had a salt appetite. We then
>adapted to a particularly salty diet and acquired even more of
>a taste for the stuff.

This also (surprise) has been explained here many many times in ever
simpler language; the salt appetite and salt hunger in the face of
deficiency is something which evolves in animals which *do not* live
on diets with a lot of salt. Animals which *do* live on such diets
either never evolve such an appetite or they lose it.

Here are some past posts to explain this to those who, unlike Crowley,
have an open mind and are able to learn from the results of scientific
studies (I only say this last because he has been shown this info, with
refs, repeatedly for months now and still refuses to accept this basic
fact of physiology):
************** relevant quotes from old posts **********
You are misunderstanding what is involved in salt hunger and salt
appetite. Mammals which normally intake an excess of salt do not,
according to experimental evidence, possess the instinctive drive
to take in salt. They either never developed this drive (or it was
lost) because they didn't need it.

HH> This 'salt appetite', business should indicate, if anything
HH> that we are somehow used to more salt than we get via
HH> vegetables and not non-marine ancestry. On the other hand
HH> salt is given to cattle and sheep too, so maybe it has nothing
HH> to do with anything.

You've put forward two possibilities there, and neither is correct.
Animals which exhibit "salt appetite" are those for whom such a
mechanism has had important survival value during their evolution.
Marine animals, for instance, have never had a need to search for
or crave salt -- quite the opposite. On the other hand, animals
such as humans, sheep, rats, rabbits -- and indeed most all
terrestrial non-carnivores (Carnivores get plenty of salt from meat)
-- have evolved in environments in which this salt appetite was a
crucial need, and consequently they typically exhibit such an appetite.

We, OTOH, are adapted to live on a low-salt diet, although, as is
common with mammals so adapted, we like salt and sometimes overdo
it considerably given the opportunity.
************** end quotes from old posts **********

>Has anyone done experiments on the
>amount of salt chimps (or other primates) would eat given a
>choice between equivalent low-salt and high-salt foods? It
>could be done in any zoo. If the figure worked out to
>significantly less than the human one, it would be good support
>for the theory of a high consumption of seafood in our recent
>evolutionary history (and maybe for the AAT as well).

Yes, Derek Denton -- who is an expert on mammalian reactions to salt
-- has done studies with chimps (wild chimps, because chimps
in captivity generally have a higher salt diet than wild chimps) and
found their responses to salt -- salt appetite, hunger in the face of
deficiency, and unhealthy reactions to high salt levels -- to be just
like humans'. This is, of course, good support for the idea that your
above theory is wildly incorrect.

Jim Moore e-mail:jimm...@inforamp.net

Elaine Morgan

unread,
May 21, 1996, 3:00:00 AM5/21/96
to

In article <DrGvD...@inter.NL.net> ghan...@inter.NL.net wrote...


> >where there is considerable thermal stress and low humidity - and then
> >returned to the forest where the glands gradually became non-functional.
> >Do you really think that?
>
> No,but I doubt that the assumption that the eccrine sweatglands in Gorillas and
> Chimps are entirely non-functional.

So do I. That is why I tried to imagine what the function can originally
have been. (and still may be - an emollient one) If you mean you doubt
that the glands fail to function in reponse to overheating
you have to argue that point with Montagna, not with me.

Elaine

Phillip Bigelow

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May 22, 1996, 3:00:00 AM5/22/96
to

Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:
>In article <4nlt8t$i...@ra.cc.wwu.edu>
> phi...@lubricant.free.org "Phillip Bigelow" writes:
>
>> If large quantities of salt(s) are ingested, why don't we sweat more,
>> even if we are *not* over-heated, or even if we are *not* exerting
>> ourselves?


>An AAT version would say that consumption of relatively large amounts
>of salt (say 20 g per day) only occurred when the hominids were at
>sea level in tropical climes. So sweating was automatically tied
>to consumption; no biological mechanism was needed.


It's an untestable theory. Therefore, it is, scientifically-speaking, an
example of circular logic. Elaine is using as "evidence" for her aquatic
ape theory the scenario you gave...which is itself, a theory. Or more
accurately, it is an assumption.

You can't base a theory on an assumption.

>> This whole salt-ballance and salt-serum concentration debate is getting
>> nowhere. There is no clear-cut *direct* relationship (cause-and-effect
>> relationship) between salt ballance in the plasma and the amount of sweat
>> we excrete. On the contrary, we sweat either when we are over-heated,
>> and/or when we exert, or when we are emotionally-excited.

>If we sweat the same (say 5 litres) each day then the more salt we eat


>the more we will excrete through sweating. Isn't this correct?


If we eat an over-dosage of salt, and we use the excretion mechanism of
some marine animals as our model, we should develop a crust of excreted
salt on our bodies.
Since this doesn't happen with humans, Elaine Morgan's comparison of
hominids with those marine animals that actually use this mechanism is
baseless.


>> In a cool-temperature environment, when a calm at-rest individual
>> ingests excessive salt, the kidneys do the work. Not the sweat glands.
>> Period. Case closed. The blood salt-ballance issue, although
>> scientifically well-understood, is not relevant to this
>> particular discussion.

>But our evolution was not in a cool-temperature environment.


It doesn't matter. The at-rest *modern* human in the hypothetical
experiment I mentioned above wouldn't excrete more salt through their
pores after said individual ate an over-dosage of salt. The salt would be
excreted through the kidneys. The at-rest calm and cool individual will
not sweat under such circumstances. The above experiment is the *ideal*
experiment to conduct to show that Elaine's ideas are (pun intended) "all
wet".


>
>I agree that not a great deal appears to hang on it. Our kidneys
>seem quite well able to cope with 20g or thereabouts of salt -
>given a good supply of water. But sweating needs an explanation;


In all terrestrial mammals that sweat, zoologists and animal anatomists
explain sweating as one type of thermo-regulation.
I really don't get this "sweating-salt ballance" discussion at all. It
seems so non-relevant to the AAT(H) discussion. Am I missing something
so profound that the point is going over my head?
<pb>

chris brochu

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May 22, 1996, 3:00:00 AM5/22/96
to

In article <4nssk7$a...@news.cc.ucf.edu> Thomas Clarke,

cla...@acme.ist.ucf.edu writes:
>I believe you are mistaken. I found contradictory data in
>Kuno, Yas (1956); _Human Perspiration_; Charles C. Thomas Publisher,
>Springfield, IL; 416pp.

Indeed, I was mistaken. I was relying on class notes from a course I
took several years ago, and either I wrote something down incautiously,
or the instructor was wrong.

chris

Phillip Bigelow

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May 23, 1996, 3:00:00 AM5/23/96
to

cla...@acme.ist.ucf.edu (Thomas Clarke) wrote:

>In the chapter on the Chemistry of Sweat there is
>a discussion of the effect of salt intake on the rate of sweating.
>"In the experiments of Sengoku (1941), which were made on three
>subjects, salt intake was entirely stopped for six to seven days while
>the subjects were made to sweat profusely once a day. The chloride

^^^^

>concentration of sweat measured during maximal sweating fell to 1/8 to
>1/10 of the level before the salt deficiency while the fall of cloride
>in the blood was not remarkable.


I'm following along so far...


>Lock, Talbot and Jones and Worcester
>(1951) observed the effect of varying the intake of sodium chloride and
>potassium salts. Two subjects were given diets containing very large
>amounts of sodium chloride for ten days and found that the chloride-
>index above mentioned rose considerably. " (page 230,


I assume that, in this study too, the subjects were *made* to sweat, as
was the case with the other study. Could sweating spontaneously occur in
at-rest, cool, calm subjects who ingested large amounts of salt?
<pb>

Phillip Bigelow

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May 23, 1996, 3:00:00 AM5/23/96
to

jimm...@inforamp.net (Jim Moore) wrote:

>In reply to a message by Paul Crowley

>>Has anyone done experiments on the


>>amount of salt chimps (or other primates) would eat given a
>>choice between equivalent low-salt and high-salt foods?

>Yes, Derek Denton -- who is an expert on mammalian reactions to salt
>-- has done studies with chimps (wild chimps, because chimps
>in captivity generally have a higher salt diet than wild chimps) and
>found their responses to salt -- salt appetite, hunger in the face of
>deficiency, and unhealthy reactions to high salt levels -- to be just
>like humans'. This is, of course, good support for the idea that your
>above theory is wildly incorrect.


Geez, and to think there is STILL an on-going debate on this topic in
this newsgroup.
<pb>


Jim Moore

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May 23, 1996, 3:00:00 AM5/23/96
to

In reply to a message by Phillip Bigelow on 23-May-96 01:14:37:

>Geez, and to think there is STILL an on-going debate on this topic in
>this newsgroup.
> <pb>

It's been going on since at least last July, believe it or not. At
least Elaine is smart enough to realize her mistake after only *10
months* of explanation and data. Perhaps the fact that this relatively
simple problem took 10 months to sink in is the reason she hasn't seen
the reaction she thought she might to her dropping this line of
evidence... i.e. sheer exhaustion.

Jim Moore e-mail:jimm...@inforamp.net


Thomas Clarke

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May 23, 1996, 3:00:00 AM5/23/96
to

In article <4ntq7k$m...@ra.cc.wwu.edu> writes:

> I really don't get this "sweating-salt ballance" discussion at all. It
> seems so non-relevant to the AAT(H) discussion. Am I missing something
> so profound that the point is going over my head?

You are right, it actually has nothing to do with the AAT.
The only thing that teh human sweat apparatus and its responsiveness
to dietary salt intake proves is that at some point in
the past hominds with "salty sweat" had greater reproductive
success leading to wide spread "salty sweat" genes among hominds.

The only thing that comes to mind that might provide this
differential reproductive success is a salty diet so that
those hominds without the extra salt elimination ability
were chronically ill-nourished.

Any other ideas?

Tom Clarke

Paul Crowley

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May 23, 1996, 3:00:00 AM5/23/96
to

In article <4ntq7k$m...@ra.cc.wwu.edu>
phi...@lubricant.free.org "Phillip Bigelow" writes:

> Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:
> > phi...@lubricant.free.org "Phillip Bigelow" writes:
> >
> >> If large quantities of salt(s) are ingested, why don't we sweat more,
> >> even if we are *not* over-heated, or even if we are *not* exerting
> >> ourselves?
>
> >An AAT version would say that consumption of relatively large amounts
> >of salt (say 20 g per day) only occurred when the hominids were at
> >sea level in tropical climes. So sweating was automatically tied
> >to consumption; no biological mechanism was needed.
>
> It's an untestable theory. Therefore, it is, scientifically-speaking, an
> example of circular logic. Elaine is using as "evidence" for her aquatic
> ape theory the scenario you gave...which is itself, a theory. Or more
> accurately, it is an assumption.
> You can't base a theory on an assumption.

This is nonsense. You ask a question. I suggest an answer which is
eminently "testable". ("Do humans regularly sweat in hot climes?").
You then say the answer is untestable theory based on an assumption.
They are empty words.

> If we eat an over-dosage of salt, and we use the excretion mechanism of
> some marine animals as our model, we should develop a crust of excreted
> salt on our bodies.
> Since this doesn't happen with humans, Elaine Morgan's comparison of
> hominids with those marine animals that actually use this mechanism is
> baseless.

It does happen with humans. Dr Holloway had a post here about nine
months ago describing how he got caked in sweated-out salt every day
when working on oil rigs.

> >But our evolution was not in a cool-temperature environment.
>
> It doesn't matter. The at-rest *modern* human in the hypothetical
> experiment I mentioned above wouldn't excrete more salt through their
> pores after said individual ate an over-dosage of salt. The salt would be
> excreted through the kidneys. The at-rest calm and cool individual will
> not sweat under such circumstances. The above experiment is the *ideal*
> experiment to conduct to show that Elaine's ideas are (pun intended) "all
> wet".

No one has proposed an automatic sweating response to over-dosage of
salt. You're creating a strawman. To repeat: if we evolved in an
environment where heavy sweating occured daily (as seems very likely)
such an automatic response would not have been needed.

> I really don't get this "sweating-salt ballance" discussion at all. It
> seems so non-relevant to the AAT(H) discussion. Am I missing something
> so profound that the point is going over my head?

Sweating is a remarkable human phenomenon. Salt-excretion through
sweat is another. Any theory of human evolution has to explain them.
They show that we evolved in a hot enviroment with plenty of readily
available fresh water and, arguably, that we had a high-salt diet.
Try listing such environments which also had a good supply of high-
protein (possibly salty) food.

Paul.

Paul Crowley

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May 23, 1996, 3:00:00 AM5/23/96
to

In article <4598.6715...@inforamp.net>
jimm...@inforamp.net "Jim Moore" writes:

> In reply to a message by Paul Crowley on 21-May-96 20:35:04:
> >In article <843.6714...@inforamp.net>
> > jimm...@inforamp.net "Jim Moore" writes:
>
> >> Sweat does vary in salt content, as a result of the fluid being pumped
> >> against a gradient, but for the myriad reasons that obviously haven't
> >> sunk in to some skulls, it isn't a salt excretion mechanism.
>
> >You drink fresh water; you sweat salty water; ergo, you lose salt.
>
> As has been explained here many many times in ever simpler language,
> what you describe is an uncontrolled process that entails severe health
> risks;

But it *is* a feature of our anatomy. Its advantages must have
outweighed its dangers in our evolutionary history.

> it is not an excretion mechanism, which by its nature must be
> controlled, and which do not offer severe health risks in normal use.

It may not be "perfectly designed". But it's there and it works.

> Not to mention that for a creature in a saltwater environment, this
> would also require massive amounts of fresh water.

Our sweating behaviour indicates that a daily requirement of, very
roughly, five-ten litres per day was needed when active in a hot
enviroment. This would have been adequate for the excretion of,
say, 20 gram of salt per day by both sweat and urination.

> As has been explained here many many times in ever simpler language,
> when sweating you lose far more water than salt, and salt is in fact
> reabsorbed into the plasma when sweating. (It's sorta like having a
> strainer with holes that stop most of a water/solid mixture.) This
> is not the action of an excretion mechanism, but it is the action of
> a conservation mechanism.

OK, as an excretion mechanism it might have been better designed.
That does not stop it being one. I know nothing of the physiology
but could the "conservation" aspect be a relatively recent change,
developed after h.erectus/h.s.s. began to exploit inland habitats?

> the salt appetite and salt hunger in the face of
> deficiency is something which evolves in animals which *do not* live
> on diets with a lot of salt. Animals which *do* live on such diets
> either never evolve such an appetite or they lose it.

A salt deficit in a mammal appears to be fatal. If we had a
population which lived on a high-salt diet by the coast (and, let's
say, lost any salt appetite) and then gradually moved inland, how
long would it take to re-establish the appetite? Ten, twenty, two-
hundred generations? (Or 250, 500, or 5,000 years?) -- eye-blinks.

Paul.

Phillip Bigelow

unread,
May 24, 1996, 3:00:00 AM5/24/96
to

Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:
>In article <4ntq7k$m...@ra.cc.wwu.edu>
> phi...@lubricant.free.org "Phillip Bigelow" writes:

>> If we eat an over-dosage of salt, and we use the excretion mechanism of
>> some marine animals as our model, we should develop a crust of excreted
>> salt on our bodies.
>> Since this doesn't happen with humans, Elaine Morgan's comparison of
>> hominids with those marine animals that actually use this mechanism is
>> baseless.


>It does happen with humans. Dr Holloway had a post here about nine
>months ago describing how he got caked in sweated-out salt every day
>when working on oil rigs.

^^^^^^^

Alex is indeed right: you are rather dense.
To re-phrase (in order to match your limited abilities to follow along in
the flow of this discussion):

If an AT REST, COOL, and CALM human test subject is fed an over-dosage of
salt, said test subject will NOT develop a crust of excreted salt on it's
body.
To repeat: this response is NOT the same response that some marine
animals have to the same experimental conditions.

>> >But our evolution was not in a cool-temperature environment.


>> It doesn't matter. The at-rest *modern* human in the hypothetical
>> experiment I mentioned above wouldn't excrete more salt through their
>> pores after said individual ate an over-dosage of salt. The salt would be
>> excreted through the kidneys. The at-rest calm and cool individual will
>> not sweat under such circumstances. The above experiment is the *ideal*
>> experiment to conduct to show that Elaine's ideas are (pun intended) "all
>> wet".


>No one has proposed an automatic sweating response to over-dosage of
>salt. You're creating a strawman.


In order to invoke the purported homology to the salt-elimination
response of some marine animals, then you HAVE to propose such a
automatic sweating response for humans.
Since humans don't posess such a homology with the marine animals in
question (seals, sea birds, etc.), then the whole
"sweating-evidence" that you claim to be valid evidence is actually crap.

>> I really don't get this "sweating-salt ballance" discussion at all. It
>> seems so non-relevant to the AAT(H) discussion. Am I missing something
>> so profound that the point is going over my head?


>Sweating is a remarkable human phenomenon. Salt-excretion through
>sweat is another. Any theory of human evolution has to explain them.
>They show that we evolved in a hot enviroment with plenty of readily
>available fresh water and, arguably, that we had a high-salt diet.


You mean, such as the hot- dry mosaic grass-land/open-forest canopy
environments, with interspersed fresh-water riparian zones? Is that the
environment you are talking about? If so, then I agree with you.


>Try listing such environments which also had a good supply of high-
>protein (possibly salty) food.

The hot-dry mosaic grass-land and open forest canopy had *abundant* salty
food for the early hominids to readily exploit to the fullest:

Assuming a partial scavenging ecology for the hominids (not a
particularly unreasonable assumption, considering that today's extant
primates scavenge meat on occassion), then the meat that said hominids
dined on would supply an over-abundance of salt to their diets...yes,
indeed, more salt than is really needed to maintain good health.

Again...I hate to keep asking this question, but I am really snowed-over
as to the relevancy of "sweating" in the AAT(H) debate. Am I missing
something in this salt-sweat-saline-ballance discussion that is so
profound that it escapes me?
<pb>

Jim Moore

unread,
May 24, 1996, 3:00:00 AM5/24/96
to

In reply to a message by Thomas Clarke on 23-May-96 17:30:16:
>In article <4ntq7k$m...@ra.cc.wwu.edu> writes:

>> I really don't get this "sweating-salt ballance" discussion at all. It
>> seems so non-relevant to the AAT(H) discussion. Am I missing something
>> so profound that the point is going over my head?

>You are right, it actually has nothing to do with the AAT.


>The only thing that teh human sweat apparatus and its responsiveness
>to dietary salt intake proves is that at some point in
>the past hominds with "salty sweat" had greater reproductive
>success leading to wide spread "salty sweat" genes among hominds.

Sweat is not "responsive" to dietary salt. It is responsive to many
other stimuli, but not to salt. If sweat was in some way due to a
salty diet, we would certainly sweat due to dietary salt intake, but
we don't. We would also *not see* the human salt appetite in that
case. Your statements above also seem to suggest that salt in sweat is
something odd in humans, which is not true.

Jim Moore e-mail:jimm...@inforamp.net


ROBERT SAUNDERS

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May 24, 1996, 3:00:00 AM5/24/96
to

In article <832710...@crowleyp.demon.co.uk> Paul Crowley <Pa...@crowleyp.demon.co.uk> writes:
>From: Paul Crowley <Pa...@crowleyp.demon.co.uk>
>Subject: Re: Death of a hypothesis
>Date: Tue, 21 May 96 20:35:04 GMT

>In article <843.6714...@inforamp.net>
> jimm...@inforamp.net "Jim Moore" writes:

>> Sweat does vary in salt content, as a result of the fluid being pumped
>> against a gradient, but for the myriad reasons that obviously haven't
>> sunk in to some skulls, it isn't a salt excretion mechanism.

>You drink fresh water; you sweat salty water; ergo, you lose salt.

Don't be so obtuse. Animals do not subsist on distilled water. All water
contains minerals and salts. More to the point, animals are eating plants and
other animals, which also contain a variety of minarals and salts. No
surprise there.

Robert

Phil Nicholls

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May 26, 1996, 3:00:00 AM5/26/96
to

Paul Crowley (Paul Crowley <Pa...@crowleyp.demon.co.uk>) writes:

>In article <DrGvK...@inter.NL.net>
> ghan...@inter.NL.net "Gerrit Hanenburg" writes:

>> Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:
>> >> But in an environment where evaporative cooling doesn't work well at all,
>> >> it would be the best choice for thermoregulation?
>>
>> >It would be the best choice because it was the only one readily
>> >available. Given the plentiful water supply, it was good enough.
>> >What alternatives would you suggest were possible?
>>
>> Small overall size and relative long limbs (high surface to volume ratio)

>And what was Lucy? - About as small (I guess) as a hominid can get.
>OK, male afarensis were large, but the size of males is relatively
>unimportant. They probably died well before the females.

Why? What information allows you to reach this conclusion?

> From a breeding point of view, mature females could outnumber mature males
>by ten to one, although I'd say that they proportion was probably closer to two to one or three to one.

Why? What is your basis for saying this?

Phil Nicholls

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May 26, 1996, 3:00:00 AM5/26/96
to

Paul Crowley (Paul Crowley <Pa...@crowleyp.demon.co.uk>) writes:

>In article <843.6714...@inforamp.net>
> jimm...@inforamp.net "Jim Moore" writes:

>> Sweat does vary in salt content, as a result of the fluid being pumped
>> against a gradient, but for the myriad reasons that obviously haven't
>> sunk in to some skulls, it isn't a salt excretion mechanism.

>You drink fresh water; you sweat salty water; ergo, you lose salt.

You sweat salty water all the time. However, sweat is less salty
than the blood. That's what hypotonic means. It also means that
if sweat is hypotonic, the more you sweat the saltier your blood
becomes. Hence it is not a mechanism for excreting salt. The kidney
does a fine job of that.

>> If anything -- as has been pointed out -- it acts to conserve salt
>> rather than eliminate it.

>How does losing salt conserve it?

Because it isn't the AMOUNT of salt that is important, it is the
CONCENTRATION OF SALT. IF sweat is hypotonic the more you sweat the
high the overall concentration of salt.


>> This also fits with our salt appetite, a feature
>> which *does not* fit with a marine background.

>Why? The LCA almost certainly had a salt appetite. We then
>adapted to a particularly salty diet and acquired even more of

>a taste for the stuff. Has anyone done experiments on the

>amount of salt chimps (or other primates) would eat given a

>choice between equivalent low-salt and high-salt foods? It
>could be done in any zoo. If the figure worked out to
>significantly less than the human one, it would be good support
>for the theory of a high consumption of seafood in our recent
>evolutionary history (and maybe for the AAT as well).

>Given the salt appetite of chimps, it is very, very suprising


>that they don't forage for fresh-water molluscs. It's quite
>likely that that was the first proto-hominid behaviour to be
>adopted, leading in time to foraging on the seashore, leading
>then to bipedalism.

There is so much wrong with this statement it is difficult to begin.
Paul, all organisms require salt because salt provides sodium ions
which in turn are critical to the function of the nervous system
(propagation of nerve impulses). It is a MAMMALIAN characteristic.
Using your logic, all organisms should be aquatic.

And if you think walking in the surf increases bipedal stability you
haven't done it recently.

>BTW I see that the normal adult consumption is 9 grams a day,
>increasing hypertension and heart disease. I bet people who
>sweat a lot have fewer such problems. Exercise is known to be
>beneficial; perhaps the sweating is an important element.
>Research should be done on regular but non-energetic sweaters,
>such as those with sedentary occupations in hot areas. It
>would be easy enough to get historical records and see how
>many died of heart problems as compared with other comparable
>groups. Bus drivers in tropical cities as against those in
>temperate ones, might be a possibility. Again the
>introduction of air-conditioning in buses (or generally)
>should increase, or have increased, hypertension. Records
>from Greyhound might tell a story.

>Paul.

Phil Nicholls pn...@globalone.net

Paul Crowley

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May 26, 1996, 3:00:00 AM5/26/96
to

In article <4o33n7$f...@ra.cc.wwu.edu> bh...@scn.org "Phillip Bigelow" writes:

> Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:

> >No one has proposed an automatic sweating response to over-dosage of
> >salt. You're creating a strawman.
>
> In order to invoke the purported homology to the salt-elimination
> response of some marine animals, then you HAVE to propose such a
> automatic sweating response for humans.
> Since humans don't posess such a homology with the marine animals in
> question (seals, sea birds, etc.), then the whole
> "sweating-evidence" that you claim to be valid evidence is actually crap.

You insist on a strawman. Who has sought to invoke "a purported
homology to the salt-elimination response . . ."? You might as well
say that "in order to invoke the purported homology for breathing . .
. . . you HAVE to propose a breathing hole at the back of the head"
and since we dont have such holes then the AAT is "actually crap".
It makes for an easy, if very stupid, argument.

It's very simple: h.s.s. sweats a lot; it also can excrete a
substantial amount of salt in its sweat. This certainly shows
that its evolution was in a hot, very well-watered environment
and *indicates* the possibility (if not probability) of a high-
salt diet.

> >Sweating is a remarkable human phenomenon. Salt-excretion through
> >sweat is another. Any theory of human evolution has to explain them.
> >They show that we evolved in a hot enviroment with plenty of readily
> >available fresh water and, arguably, that we had a high-salt diet.
>
> You mean, such as the hot- dry mosaic grass-land/open-forest canopy
> environments, with interspersed fresh-water riparian zones? Is that the
> environment you are talking about? If so, then I agree with you.

Such environments are generally low on salt, and (since they're
"hot-dry") also low on water. Numerous primates and other mammals
have evolved in them and none show the extraordinary adaptations
and most peculiar feature of h.s.s.

Paul.

Paul Crowley

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May 26, 1996, 3:00:00 AM5/26/96
to

In article <4o9orf$o...@news.global1.net>
pn...@globalone.net "Phil Nicholls" writes:

> Paul Crowley (Paul Crowley <Pa...@crowleyp.demon.co.uk>) writes:
>

> >And what was Lucy? - About as small (I guess) as a hominid can get.
> >OK, male afarensis were large, but the size of males is relatively
> >unimportant. They probably died well before the females.
>
> Why? What information allows you to reach this conclusion?

Basic biology. The breeding unit in most birds and animals is the
mother/child. This applies to hominoids, except gibbons and h.s.s.
Generally _from_a_breeding_point_of_view_ males are irrelevant
except for fertilisation. Females will find a close approximation
to the "best" form for survival in their environment, whereas males
may acquire the equivalent of peacocks' tails. I'm suggesting
that male afarensis needed large size for the kind of male/male or
inter-group competition that we see in gorillas or chimps. Their
size would have been determined more by those factors than by
environmental pressures. Consequently they were bigger than they
"ought" to have been, given the need for a high surface area to
body weight ratio (to inhibit over-heating); so their life
expectancy would have been shorter, even without the additional
deaths caused by fighting.

> > From a breeding point of view, mature females could outnumber mature males

> >by ten to one, although I'd say that the proportion was probably closer to


> two to one or three to one.
>
> Why? What is your basis for saying this?

Only a rough guess, to give you an idea of what I am talking about.
A ten to one proportion would seem too weak a ratio to sustain
against other raiding hominids. But with early deaths from an
over-large anatomy and from fighting, 3/1 or 2/1 seems more likely.

Paul.

Paul Crowley

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May 26, 1996, 3:00:00 AM5/26/96
to

In article <4o9oro$o...@news.global1.net>
pn...@globalone.net "Phil Nicholls" writes:

> Paul Crowley (Paul Crowley <Pa...@crowleyp.demon.co.uk>) writes:
>

> >You drink fresh water; you sweat salty water; ergo, you lose salt.
>
> You sweat salty water all the time. However, sweat is less salty
> than the blood. That's what hypotonic means. It also means that
> if sweat is hypotonic, the more you sweat the saltier your blood
> becomes. Hence it is not a mechanism for excreting salt. The kidney
> does a fine job of that.

I suppose everyone knows that the word "salary" comes from the
Latin "salarium", the money the Romans paid their soldiers to buy
salt. In other words, for the past 5,000 years or more we have
usually lived in salt-poor environments; so it's not surprising
that our physiology tries to conserve salt when it has a limited
supply.

But when we have an excess of it and when we drink plenty of
fresh water, we do excrete it through our sweat glands. This is
an undeniable phenomenon that should be explained. It is quite
clear that our physiology requires and expects the daily
consumption of large quantities of water. That it can use
this to excrete surplus salt is, also, not surprising. As you
say the kidney does a fine job, but when we sweat a lot we often
have little fluid left over for urine. If sweat did not take out
salt when on a high-salt diet, our kidneys might not be able to
cope.

> >Given the salt appetite of chimps, it is very, very suprising
> >that they don't forage for fresh-water molluscs. It's quite
> >likely that that was the first proto-hominid behaviour to be
> >adopted, leading in time to foraging on the seashore, leading
> >then to bipedalism.
>
> There is so much wrong with this statement it is difficult to begin.
> Paul, all organisms require salt because salt provides sodium ions
> which in turn are critical to the function of the nervous system
> (propagation of nerve impulses). It is a MAMMALIAN characteristic.
> Using your logic, all organisms should be aquatic.

You're reading something into my speculations that I can't see.
Most terrestrial mammals go to much trouble to find salt. Fresh
water molluscs would provide it. Foraging for them needs basic
manipulative skills such as chimps now possess.

> And if you think walking in the surf increases bipedal stability you
> haven't done it recently.

No, think of the female with child. It's the impossibility
of carrying an infant in the ventral position while walking
quadrupedally through any kind of surf. Two things follow:
(a) the child has to be put down, away from the water;
(b) the female is free to stand tall.

Paul.


Phil Nicholls

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May 27, 1996, 3:00:00 AM5/27/96
to

Paul Crowley (Paul Crowley <Pa...@crowleyp.demon.co.uk>) writes:

>In article <4ntq7k$m...@ra.cc.wwu.edu>
> phi...@lubricant.free.org "Phillip Bigelow" writes:

>> Paul Crowley <Pa...@crowleyp.demon.co.uk> wrote:
>> > phi...@lubricant.free.org "Phillip Bigelow" writes:
>> >

>> >> If large quantities of salt(s) are ingested, why don't we sweat more,
>> >> even if we are *not* over-heated, or even if we are *not* exerting
>> >> ourselves?
>>
>> >An AAT version would say that consumption of relatively large amounts
>> >of salt (say 20 g per day) only occurred when the hominids were at
>> >sea level in tropical climes. So sweating was automatically tied
>> >to consumption; no biological mechanism was needed.
>>
>> It's an untestable theory. Therefore, it is, scientifically-speaking, an
>> example of circular logic. Elaine is using as "evidence" for her aquatic
>> ape theory the scenario you gave...which is itself, a theory. Or more
>> accurately, it is an assumption.
>> You can't base a theory on an assumption.

>This is nonsense. You ask a question. I suggest an answer which is
>eminently "testable". ("Do humans regularly sweat in hot climes?").
>You then say the answer is untestable theory based on an assumption.
>They are empty words.

Since we know that humans regularly sweat in "hot climes" how is this
a test?

The facts are these:

Sweat is hypotonic. Even when excess salt is consumed, sweat is
hypotonic. Hence it cannot be an excretion since excretions
concentrate excreted products.

Mammals the kidney is the primary route for excreting excess salt.

>> If we eat an over-dosage of salt, and we use the excretion mechanism of
>> some marine animals as our model, we should develop a crust of excreted
>> salt on our bodies.
>> Since this doesn't happen with humans, Elaine Morgan's comparison of
>> hominids with those marine animals that actually use this mechanism is
>> baseless.

>It does happen with humans. Dr Holloway had a post here about nine
>months ago describing how he got caked in sweated-out salt every day
>when working on oil rigs.

Yes and Dr. Holloway was not consuming excess salt at that time, was
he? No one argues that there is salt in sweat. However, ask yourself
why people who work outside and sweat alot drink electrolytes or take
salt tabs? Humans lose salt and water when they sweat. They replace
the water by drinking but if they don't replace the salt too they will
stroke.

>> >But our evolution was not in a cool-temperature environment.
>>
>> It doesn't matter. The at-rest *modern* human in the hypothetical
>> experiment I mentioned above wouldn't excrete more salt through their
>> pores after said individual ate an over-dosage of salt. The salt would be
>> excreted through the kidneys. The at-rest calm and cool individual will
>> not sweat under such circumstances. The above experiment is the *ideal*
>> experiment to conduct to show that Elaine's ideas are (pun intended) "all
>> wet".

>No one has proposed an automatic sweating response to over-dosage of


>salt. You're creating a strawman. To repeat: if we evolved in an
>environment where heavy sweating occured daily (as seems very likely)
>such an automatic response would not have been needed.

But you claimed that environment would be hot and humid rather than
hot and dry and sweating doesn't have much of an effect in humid
environments.

>> I really don't get this "sweating-salt ballance" discussion at all. It
>> seems so non-relevant to the AAT(H) discussion. Am I missing something
>> so profound that the point is going over my head?

>Sweating is a remarkable human phenomenon. Salt-excretion through
>sweat is another.

Sweating is a remarkable human phenomenon with precursors in non-human
primates. That sweat contains salt is unremarkable. The fact that
sweat is hypotonic indicates it is not an excretion. Why you cannot
see the significance of this is beyond me.

> Any theory of human evolution has to explain them.

As I pointed out, there is no need to explain why sweat is salty. If
you claim sweat is an excretion mechanism then you have to explain why
salt in sweat is less concentrated that salt in blood plasma or tissue
fluids.

Sweating is a thermoregulator mechanism. It is most effective in hot
dry environments.

>They show that we evolved in a hot enviroment with plenty of readily
>available fresh water and, arguably, that we had a high-salt diet.

African savannahs support vast heards of large mammals, all of which
require plenty of readily available fresh water. Humans have the
ability to undergo voluntary dehydration, a fact that is inconsistant
with aquatic evolution.

>Try listing such environments which also had a good supply of high-
>protein (possibly salty) food.

Early hominid protein requirements are unlikely to be greater than
those of other primates. A high protein diet is not a requirement
for early hominid evolution.

Paul Crowley

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May 27, 1996, 3:00:00 AM5/27/96
to

In article <4oc9pv$9...@news.global1.net>
pn...@globalone.net "Phil Nicholls" writes:

> Sweat is hypotonic. Even when excess salt is consumed, sweat is
> hypotonic. Hence it cannot be an excretion since excretions
> concentrate excreted products.

Excretions *usually* concentrate excreted products. You are
creating a rule from an observed generality -- but there are
numerous exceptions in nature and your "law" is not valid. Many
animals have large flows of matter, mostly liquid but also solid
and even gaseous material flowing through their bodies. They
expel waste material into them at low concentrations. So long
as the organism can rely on a sustained inflow of (say) water,
there is no penalty in temporarily increasing the concentration
of the waste matter (such as salt in the blood plasma) during
the excretion process. The evolution of the mechanism will
occur if it benefits the organism in its current environment.
If early hominids sweated a lot, regularly drank water, and
consumed shellfish, those hominids who could excrete salt in
sweat would have an advantage over those that didn't.

It's not an engineering problem. It's an evolutionary one.

> Mammals the kidney is the primary route for excreting excess salt.

That does not make it the only one.

Paul.

Richard Foy

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May 27, 1996, 3:00:00 AM5/27/96
to

In article <4o9oro$o...@news.global1.net>,

Phil Nicholls <pn...@globalone.net> wrote:
>
>>You drink fresh water; you sweat salty water; ergo, you lose salt.
>
>You sweat salty water all the time. However, sweat is less salty
>than the blood. That's what hypotonic means. It also means that
>if sweat is hypotonic, the more you sweat the saltier your blood
>becomes. Hence it is not a mechanism for excreting salt. The kidney
>does a fine job of that.
>
>>> If anything -- as has been pointed out -- it acts to conserve salt
>>> rather than eliminate it.
>
>>How does losing salt conserve it?
>
>Because it isn't the AMOUNT of salt that is important, it is the
>CONCENTRATION OF SALT. IF sweat is hypotonic the more you sweat the
>high the overall concentration of salt.

Until of course the sweat is replaced with water with a lower salt
content.


>
>>Given the salt appetite of chimps, it is very, very suprising
>>that they don't forage for fresh-water molluscs. It's quite
>>likely that that was the first proto-hominid behaviour to be
>>adopted, leading in time to foraging on the seashore, leading
>>then to bipedalism.
>
>There is so much wrong with this statement it is difficult to begin.
>Paul, all organisms require salt because salt provides sodium ions
>which in turn are critical to the function of the nervous system
>(propagation of nerve impulses). It is a MAMMALIAN characteristic.
>Using your logic, all organisms should be aquatic.
>

>And if you think walking in the surf increases bipedal stability you
>haven't done it recently.

Straw man!!! He said nothing about bidpedal stability!!

--
"A shadow is the thing which is generated when you position yourself
between it and the sun." -- Anonymous

URL http://www.he.tdl.com/~hfanoe/udc.html

Elaine Morgan

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May 27, 1996, 3:00:00 AM5/27/96
to

0. Elaine is using as "evidence" for her aquatic

> >> ape theory the scenario you gave...which is itself, a theory. Or more
> >> accurately, it is an assumption.

No. If you read my stuff carefully I never use the putative scenario as
evidence. I never say the scenario happened. I point to anomalous facts
about human anatomy and say "Here is a possible hypothesis which if true
would make these facts easier to explain."

>
> As I pointed out, there is no need to explain why sweat is salty.

No, that was not the object of the exercise. There is however, it seems
to me, a need to explain why we are the most profusely sweating animals
in the whole of creation. There is a need to explain why hunam
sweating as a
thermoregulatory system is so creaky and wasteful and why it has been
described as a biological blunder because of its inefficiency. The salt
thing , since we have tears as well as sweat of unparallelled
profuseness (still unexplained) was an attempt to account for these
things. An unsuccessful attempt. But if you don't make mistakes you
don't make anything - and those questions are still without answers.

Elaine


Elaine Morgan

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May 27, 1996, 3:00:00 AM5/27/96
to

In article <603.6717...@inforamp.net> jimm...@inforamp.net wrote...

>
> In reply to a message by Phillip Bigelow on 23-May-96 01:14:37:
>
> >Geez, and to think there is STILL an on-going debate on this topic in
> >this newsgroup.
> > <pb>

There's a hell of a lot there that still lacks an explanation.

> It's been going on since at least last July, believe it or not. At
> least Elaine is smart enough to realize her mistake after only *10
> months* of explanation and data.

It takes me a long time, Jim, because I am unwilling to let go of a
possible explanation of puzzling facts until somebody comes up with a
better one - or at least a different one. You don't allow that
consideration to weigh with you at all. You are content to say:
"That is wrong, and that is wrong, and that is wrong." But when you are
asked to offer your own explanation of any of the anomalous data about
humans you grow strangely silent or hastily change the subject.
In this case nobody had come up with an alternative that covered all
the facts so I had to try to do it myself. That's what takes the time.
Maybe I'm still wrong but I'm in there pitching, not muttering "Ah,
alas we may never know...."

> Perhaps the fact that this relatively simple problem took 10 months to sink in is the reason she hasn't seen

...
Relatively simple? Come on then, tell us why you think a gorilla has
got all those eccrines, tell us why you think humans are hairless ,
tell us why you think Peter Wheeler got heat stroke in Africa because
the human sweat-cooling system takes up to half an hour to get activated
and by the time his did he had collapsed.

You are terrific with the indiscriminate use of the bulldozer, but you
will never produce anything positive. And you will rarely even stick
your neck out to support other people's positive ideas in case they
prove wrong.

You won't even try to answer the questions. You will use the usual
escape clause that you've fallen back on more than once: "A far more
interesting question, the *real* question, is why is E, Morgan so
awful.." And off you go, as happy as Larry, bless your little cotton
socks.

Elaine
>
>


Richard Foy

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May 28, 1996, 3:00:00 AM5/28/96
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In article <4oc9pv$9...@news.global1.net>,

Phil Nicholls <pn...@globalone.net> wrote:
>
>The facts are these:
>
>Sweat is hypotonic. Even when excess salt is consumed, sweat is
>hypotonic. Hence it cannot be an excretion since excretions
>concentrate excreted products.
>
>Mammals the kidney is the primary route for excreting excess salt.
>
....

>
>>It does happen with humans. Dr Holloway had a post here about nine
>>months ago describing how he got caked in sweated-out salt every day
>>when working on oil rigs.
>
>Yes and Dr. Holloway was not consuming excess salt at that time, was
>he? No one argues that there is salt in sweat. However, ask yourself
>why people who work outside and sweat alot drink electrolytes or take
>salt tabs? Humans lose salt and water when they sweat. They replace
>the water by drinking but if they don't replace the salt too they will
>stroke.

The last paragraph seems to suggest that the first paragraph is not a
valid criticsim of sweating being a way of losing *excess* salt
ingested from a high salt content diet.

That is if sweating when not consuming excess salt reguires drinking
water and ingesting salt, then sweating when one has an excess of
salt in the body would only require replacing the wanter and not the
solt to arrive and the proper concentration of solt in the body.

david l burkhead

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May 28, 1996, 3:00:00 AM5/28/96
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In article <833137...@crowleyp.demon.co.uk> Pa...@crowleyp.demon.co.uk writes:

[ 8< ]

>I suppose everyone knows that the word "salary" comes from the
>Latin "salarium", the money the Romans paid their soldiers to buy
>salt. In other words, for the past 5,000 years or more we have
>usually lived in salt-poor environments; so it's not surprising
>that our physiology tries to conserve salt when it has a limited
>supply.

I see your knowledge of history is as poor as your knowledge of
biology. Roman legionnaires were not paid "to buy salt" but were paid
_in_ salt (whence the term "he's worth his salt"). Also, the time
frame is not "the past 5,000 years or more), but much less than half that.
Also, whether or not Romans lived in a "salt-poor" environment doesn't
have a lot of effect on human evolution--they were only a small part
of the total human population and where they lived isn't going to
affect the biology of people who are not, in any way, descended from
them.

Furthermore, if the intervening 2,000 (tops) years is sufficient
to make a proposed bit of "evidence" for AAH go away, then it's enough
to make all these soft-tissue things change enough to make appeal to
them worthless for determining evolutionary history.

>But when we have an excess of it and when we drink plenty of
>fresh water, we do excrete it through our sweat glands. This is
>an undeniable phenomenon that should be explained. It is quite
>clear that our physiology requires and expects the daily
>consumption of large quantities of water. That it can use
>this to excrete surplus salt is, also, not surprising. As you
>say the kidney does a fine job, but when we sweat a lot we often
>have little fluid left over for urine. If sweat did not take out
>salt when on a high-salt diet, our kidneys might not be able to
>cope.

First, that some salt is lost with the water through sweat
requires no more "explanation" than the second law of thermodynamics.
(Is there a physicist in the house? Oh yes, that's right. . . .) It
takes energy to reduce the concentration of a material in solution by
an active process (as opposed to simply diluting it). If that were
not the case, folk wouldn't spend so much money and effort on seawater
salination plants for coastal areas lacking sufficient supply of fresh
water. That energy has to come from somewhere. Note that anything
but an isotonic excretory fluid will require energy as a change in
each direction requires a decrease in entropy of the combinations of
solutions inside and outside the body (note: this isn't a violation
of the second law since a still greater increase of entropy occurs in
generating the energy to drive the process that decreases entropy
locally).

Thus, since it _requires_ energy to make sweat isotonic, one
would think that this is a definite disadvantage (energy expended for
this process is not available for other processes like immune system,
tissue repair, or prosaic things like running--and weren't you the one
claiming that animals always live on the energetic edge?). Thus, those
who did not spend that energy, or spent less of it (leaving a closer to
isotonic sweat) would have a small, but real, advantage over their
relatives who spent the full amount of energy--unless there was some
advantage to retaining that salt.

Since the salt lost through sweating is relatively uncontrolled,
its loss monkeys with the balance of electrolytes and that balance is
_much_ more serious than the total concentration of salt. The total
concentration of salt can vary quite a bit without any immediate problem.
The balance between different salts, however, is a different matter
where very small changes can cause immediate and acute problems, problems
that can be fatal if you happen to be facing a threat at the moment--try
dealing with a predator sometime while undergoing severe cramps.


>You're reading something into my speculations that I can't see.
>Most terrestrial mammals go to much trouble to find salt. Fresh
>water molluscs would provide it. Foraging for them needs basic
>manipulative skills such as chimps now possess.

Another of those blanket assumptions that you are so famous for.
What evidence do you have that mammals "go to much trouble to find
salt"?

And if foraging for fresh water molluscs is such a wonderful thing,
since you say it's a skill that chimps already have, then why don't
they do it. Oh, wait, I remember now. You are the one that claimed
that Chimps are famously hydrophobic. Of course, that nobody seems to
have bothered to tell the _chimps_ seems to escape you.

[ 8< ]

>No, think of the female with child. It's the impossibility
>of carrying an infant in the ventral position while walking
>quadrupedally through any kind of surf. Two things follow:
>(a) the child has to be put down, away from the water;
>(b) the female is free to stand tall.

Or, if (as you often claim, but have yet to support by anything
other than claims) these infants are not able to cling themselves, then
the simplest solution is to stay _out_ of the surf.

OTOH, your response had nothing whatever to do with the comment
you were "replying" to. Whether a mother is carrying a child or not
really has little to do with whether bipedalism offers stability in
surf (which is the claim of yours that _he_ was replying to).

David L. Burkhead
dav...@dax.cc.uakron.edu
FAX: 330-253-4490


Jim Moore

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May 28, 1996, 3:00:00 AM5/28/96
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In reply to a message by david l burkhead on 28-May-96 06:35:23:


>>You're reading something into my speculations that I can't see.
>>Most terrestrial mammals go to much trouble to find salt. Fresh
>>water molluscs would provide it. Foraging for them needs basic
>>manipulative skills such as chimps now possess.

> Another of those blanket assumptions that you are so famous for.
>What evidence do you have that mammals "go to much trouble to find
>salt"?

*Some* terrestrial mammals do go to a lot of trouble to find and ingest
salt and this includes humans. *The one thing all these mammals have
in common is that they have evolved in conditions of low dietary salt*.

This point alone -- even without the many other bits of data we've seen
assembled here for several years -- is enough to discount any
likelihood of our ancestors living in a salt-replete environment.

Jim Moore e-mail:jimm...@inforamp.net


Paul Crowley

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May 28, 1996, 3:00:00 AM5/28/96
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In article <4oe6rb$6...@kira.cc.uakron.edu>
dav...@dax.cc.uakron.edu "david l burkhead" writes:

> Pa...@crowleyp.demon.co.uk writes:>
>
> >I suppose everyone knows that the word "salary" comes from the
> >Latin "salarium", the money the Romans paid their soldiers to buy
> >salt. In other words, for the past 5,000 years or more we have
> >usually lived in salt-poor environments; so it's not surprising
> >that our physiology tries to conserve salt when it has a limited
> >supply.
>
> I see your knowledge of history is as poor as your knowledge of
> biology. Roman legionnaires were not paid "to buy salt" but were paid
> _in_ salt (whence the term "he's worth his salt").

You should check before making a fool of yourself. Most good
dictionaries will suffice. Go to the OED if necessary.

> Also, the time
> frame is not "the past 5,000 years or more), but much less than half that.

Why do I have to spell everything out? I was using the Romans as an
*example* of a human population in historical times. Their lifestyle
was not untypical of the bulk of h.s.s. during the last 10,000 years
i.e. they lived mostly off cereals and vegetables.

> Furthermore, if the intervening 2,000 (tops) years is sufficient
> to make a proposed bit of "evidence" for AAH go away, then it's enough
> to make all these soft-tissue things change enough to make appeal to
> them worthless for determining evolutionary history.

Evolution did not come to a halt when farming started. It's quite
reasonable to suggest that the new lifestyle lead to changes in
certain soft-tissue matters. We have a pretty good idea of the
diet during the last 10 Kyr, but a poor one of the diet before
that. An adjustment to a greater deficit of salt in the diet
could well have been possible in the last 10 Kyr or so.

> First, that some salt is lost with the water through sweat
> requires no more "explanation" than the second law of thermodynamics.
> (Is there a physicist in the house? Oh yes, that's right. . . .)

The problem is not in the physics. It's in the evolution of the
mechanism. We have (according to the standard view) an animal living
in a salt-poor environment, that as part of its normal lifestyle
excretes (or, if you prefer, exudes) a substance which is necessary
for life. No other animal in that environment demonstrates similar
behaviour. This *does* need explanation.

> who did not spend that energy, or spent less of it (leaving a closer to
> isotonic sweat) would have a small, but real, advantage over their
> relatives who spent the full amount of energy--unless there was some
> advantage to retaining that salt.

<Rest of account of hypotonic nature of sweat snipped>.
All fine and non-controversial, as far as I can see. Certainly for
the last 10,000 years (and probably much longer) h.s.s has generally
needed to retain as much salt as possible. The evolutionary benefits
of the mechanisms you describe are indisputable. I don't get the
basic point you are trying to make. Are you sure you have one?

> that Chimps are famously hydrophobic. Of course, that nobody seems to
> have bothered to tell the _chimps_ seems to escape you.

Then someone has convinced the chimps in most zoos to put on a good
pretence of *aquaphobia*. (Not "hydrophobia" - look up a dictionary
on that as well. It has a precise meaning, not applicable to chimps.)

Paul.

Thomas Clarke

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May 28, 1996, 3:00:00 AM5/28/96
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In article <4o0do9$j...@ra.cc.wwu.edu> Phillip Bigelow <bh...@scn.org> writes:
> cla...@acme.ist.ucf.edu (Thomas Clarke) wrote:

<Induced sweating example snipped>

> I assume that, in this study too, the subjects were *made* to sweat, as
> was the case with the other study. Could sweating spontaneously occur in
> at-rest, cool, calm subjects who ingested large amounts of salt?

Don't know about salt, but I know after a riotous weekend
(too much beer, salty pretzels?) the thermal threshold for
sweating is much reduced :-)

I'll have to dig out that book again.

Tom Clarke