Re: Bipedialism and other factors and AAT
Troy Kelley (tkelley@hel4.brl.mil)
Tue, 6 Jun 1995 17:52:24 GMT
Subject: Re: Bipedalism and other factors and AAT
From: J. Moore, j#d#.moore@canrem.com
Date: Sat, 3 Jun 95 12:40:00 -0500
In article <60.1658.7295.0N1E50DD@canrem.com> J. Moore,
j#d#.moore@canrem.com writes:
>Si> So as long as we did not have to run from any predators, we were OK.
>
>And, as you've read in my other post(s), we almost certainly did not
>have to depend on running for defense from predators. Certainly not
>any long distance. So we were, as you state above, okay. But to
>realise this, you have to look at what we and our close relatives
>actually do, rather than what you would imagine they should do.
If you are talking, in some sort of round about way, about threat
displays, I realize of course that SOME animals exhibit threat displays
when cornered by a predator. By "our close relatives" I assume you mean
chimps and gorrillas, but they are not currently under a lot of predation
except from man. So they exhibit very little predatoral threat displays.
I think you are mainly talking about baboons which exhibit threat
displays as part of a defense, but this is also because they are
primarily savanna creatures which do not have the luxury of running to a
tree every time danger is encountered.
>Si> Combine this with the problem of sweating, and you have an animal
>Si> that is slow, and inefficient at moving with any significant degree
of
>Si> speed, and needs to be near water to replenish lost fluids.
>
>Si> The fact is that "Active young men will normally lose over 8 litres
of
>Si> water during a day when the desert temperature at midday is above
>Si> 40 C." "A man weighing 90 kilograms can sweat over 2 liters of water
>Si> in an hour of normal walking in a hot day in the desert."
>
>First of all, who the hell ever said that australopithecines *ever* set
>foot in the desert (besides you)?
Gee.. I didn't realize I said "Australopithecines set foot in the
desert". Thank you for explaining to me what I said.
I was mearly using a quote I had found about water consumption to
illustrate a point that hominids, when compared to other savanna
creatures, do not conserve water very well.
>
>Second, look at Peter Wheeler's (1994) statement:
>
>"The estimated total daytime drinking water requirements of a 35 Kg
>naked biped, utilising heat storage and foraging throughout the day at
>the temperatures and level of metabolic expenditure used in the present
>study [note: 35-40 degree C temperatures and a 12 hour foraging day,
>rather longer than likely actually], is approximately 1.3 litres, the
>equivalent of 3.7% of its total body mass. Since this degree of
>dehydration can be tolerated by modern humans without experiencing any
>major detrimental effects, this indicates that these animals should not
>usually have required access to drinking water more than once a day
>(Wheeler, 1991b). If the normal activity pattern of these primates also
>involved shade-seeking during the most thermally stressing period of the
>day, their requirements will have been substantially lower. Intakes as
>low as 0.7 litre, equivalent to only about 2% of total body mass, may
>have been sufficient to replace all losses incurred by a naked biped
>throughout the day if it retreated into the shade for a 4-hour period in
>the early afternoon [note: this is the common mode of activity in hot
>climates for humans, chimps, gorillas, and indeed a whole lot of
>animals; "mad dogs and Englishmen" and all that]."
You can use all the quotes on water consumption you want and I promise
you I can find quotes that will contradict you. I did however noticed
that the first part of this reference was an "estimate". I think that
the "estimated total daytime drinking requirements" by this author was a
very poor estimate.
I don't think there is really any question, no matter what quote you come
up with, that the susceptibility of early hominids to dehydration was
probably pretty high. If you look at any other creature on the savanna,
the ways in which they conserve water resources are far superior to the
human/pre-human model. Their body temperatures are generally higher,
they allow their internal body temperatures to rise in response to heat
and they don't sweat, they pant. Sweating may be an efficient cooling
mechanism for humans, but it is not an effective way to stay cool unless
there is access to plenty of water to re-hydrate the body. I really
don't think there is any argument about this.
>
>Si> can hear over the vast distances of the great plains; would lead one
>Si> to the conclusion that we must have evolved in a safe, shady, semi-
>Si> aquatic environment.
>Si> Troy Kelley
>
>"Shady" at the seashore? You've *never* been to the beach? Safe? From
>crocs and sharks we can't even see approaching? And which don't respond
>to human and chimpanzee threat displays (as big cats and other land
>predators do)?
>J. Moore, j#d#.moore@canrem.com
"You've *never* been to the beach?" - Now theres a good, well thought
out, non-antagonistic question.
And to use one of your previous quotes - "Who the hell said anything
about a seashore?" I don't think DRINKING sea water for re-hydration
would be a very effective way to say alive on the Africa savanna.
And besides that, I don't think crocodiles like salt water, in fact, I
know that they don't live in salt water.
Haven't you ever been to the beach?
Troy Kelley
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