Re: Bipedalism and other factors and AAT
J. Moore (j#d#.moore@canrem.com)
Sat, 3 Jun 95 12:40:00 -0500
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.
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)?
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]."
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)?
Jim Moore (j#d#.moore@canrem.com)
Refs:
Wheeler, Peter
1991b [I don't have the title here at present, sorry]. *Journal of
Human Evolution* 21:117-136
Wheeler, Peter
1994 "The thermoregulatory advantages of heat storage and shade-seeking
behavior to hominids foraging in equatorial savannah environments".
*Journal of Human Evolution* 24(4):339-350, April.
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