Re: An alternative to ST and AAT
Rohinton Collins (rohinton@collins.prestel.co.uk)
8 Nov 1996 21:12:11 GMT
John Waters <jdwaters@dircon.co.uk> wrote in article
<01bbcd2f$8f445e00$3a2270c2@default>...
>
> Paul Crowley <Paul@crowleyp.demon.co.uk> wrote in article
> <847317907snz@crowleyp.demon.co.uk>...
> >
> > This raises a very interesting point. For some 2.5
> million years
> > (until about 2.5 mya) hominids could not stride and
Says who?
> probably could
> > not run; if they could, they certainly did not do it
> well.
Again, says who? The australopithecines were fully adapted bipeds. Just
because their mode of locomotion was not IDENTICAL to ours does not mean
that it was not at least as efficient. Indeed an article by Owen C. Lovejoy
suggests that A. afarensis may have been even more efficient a biped than
modern humans. I am not saying that I agree (or disagree), just that you
make a very bold statement which is not backed up by any evidence
>> The
> > australopithecines had short legs, long arms and no
> waist.
Which australopithecines?
> > So why did they maintain this very strange morphology for
> so long?
Strange? It was obviously not strange at the time. It was most probably an
efficient adaptation.
> > What could have been the evolutionary pressures keeping
> them like
> > that?
There was obviously no evolutionary pressure to change. It was a stable
phenotype.
> > And change what allowed them to adopt the, more or
> less,
> > modern form?
> >
> > Has anyone attempted an answer to these questions?
>
> JW: For what it's worth, the HBT explains that the hominid
> delay in switching to a highly efficient form of bipedalism
Again, see above.
> was caused by the problem of the overheating baby.
Don't you just hate that 'overheating baby' problem? My nephew......
> When a
> hominid baby was carried in its mothers arms, the baby's
> core body
> temperature would rise.
>
> In very hot conditions, the baby would die of heatstroke if
> carried continuously by its mother.
You were there? What makes you think that a baby would be carried
continuously by its mother? Or even carried by its mother? Even if it was,
what is to say that it would not be shielded from the heat of the sun by
the mother, and therefore LESS likely to 'die of heatstroke'? Your
reasoning, John, has far too many holes in it. Australopithecine babies
were likely no less capricious than chimpanzee babies, as the level of
encephalisation was not dramatic in these species. If you do not know why
human babies are born helpless and therefore cannot gauge when this
condition may have emerged in hominid evolution, please say and I will
explain.
> The pressure for
> efficient bipedalism
Again, what was wrong with australopithecine bipedalism?
> created an evolutionary demand for
> less infantile body hair, increased number of sweat glands,
> the moulting of the foetal hair etc., to combat infantile
> overheating.
Fallacious, since I have refuted your 'overheating baby' theory.
> The maternal adaptations were an increase in subcutanous
> fat levels in the chest/breast region, and on the hips.
> These are the places where the infant comes into contact
> with the mother.
How did you arrive at this conclusion?
> The fat prevented the mother's own
> internal body heat from being conducted into the infant.
This really has no logic whatsoever.
> John.
Regards,
Roh
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