Re: Savanna: a slow demise
Thomas Clarke (clarke@acme.ist.ucf.edu)
5 Oct 1995 13:11:56 GMT
In article <44nail$3un@news.global1.net> writes:
> clarke@acme.ist.ucf.edu (Thomas Clarke) graced us with the following
> words:
> >In article <4463oo$5hj@news.global1.net> pnich@globalone.net (Phil Nicholls)
> >writes:
> >> First of all, that early hominids occupied savanna
> >> habitats is not a theory. It is a fact.
> >Is it? Where have the fossils been found?
> Early hominid fossils are found East Africa and Southern Africa.
> Paleoclimatological evidence shows them to be associated with savanna
> habitats. This really is not an issue, even for the AAH people.
But Lucy was found among crab shells. The first family in a riverine setting.
These are aquatic, probably savannah fringe aquatic, but aquatic.
Perhaps only those hominids who happened to die in an aquatic setting
had their bones fossilized and preserved, or perhaps the hominds lived
preferentially on the aquatic margins, I don't think there is a big enough
sample to tell.
> >>> I have a very simple standard that I believe all scientist use
> >> -- evidence. Show me the evidence.
> >As a person of theoretical bent, who likes to read cosmology.
> >I resent that. You imply that my interest is not scientific.
> If you are constructing your theories without evidence then you are
> engaging in groundless speculation and they are not theories at all.
> Most people I know with an interest in cosmology base there
> speculations on the available evidence.
So are you saying that the AAT has absolutely no touch with reality?
Clearly the AAT is trying to explain the same facts that the "savannah"
theory(s) attempt to explain. The AAT further offers a possible
explanation for some soft tissue differences between ape and human.
> >> Fact: Pre-hominids were forest dwellers
> >> Fact: Early hominids were savanna dwellers
> >As, I asked. is this a fact? Don't forget the 1-2 MY gap
> >in the record.
> Yes, it is a fact and again this is not in dispute.
Please explain how you know where creatures whose fossils have yet to be
found lived?
> What is in
> dispute is the side trip into the aquatic environment proposed by the
> AAH supporters and for which there is no evidence. A gap is not
> evidence.
That is news to me. I am not as well read as you in the PA area, but
as far as I can tell there is a pretty large gap.
Actually, sometimes I think that someday the scales will fall from
the PAists eyes and they will see that Lucy and the first family were
living a semi-aquatic life.
> >> The transition is critical.
> >Yes indeed. If all that is required for a knuckle walking to
> >bipedal transition is an ape and a forest margin, they why is not
> >the world today full of many bipdal ape species?
> First of all we are fairly certain that the common ancestor of modern
> apes and humans was not a knuckle-walker. It is very likely that
> knuckle-walking developed after the hominid-pongid split.
"Fairly certain" is not fact. But I take your point. So it was
trees to (area of controversy) to bipedalism for hominids, and
trees to knuckle walking for apes. (?)
> The second part of your question makes no evolutionary sense
> whatsoever.
Why? If one species became bipedal, why not two? I guess the most
successful could have killed/outcompeted the others, but this is
by no means certain.
> >> I believe it took place in the zone at
> >> which forests border on savannas. This is because some of the
> >> earliest hominids clearly retained arboreal adaptations. It makes a
> >> great deal of sense.
> >Point of logic: the retention of arboreal adaptations does not imply an
> >arboreal life style. An arboreal foot with a little webbing could
> >serve an aquatic/wading life style very well - but I stretch the evidence
> >as you do.
> Arboreal adaptations do indicate an arboreal lifestyle unless you have
> EVIDENCE to indicate otherwise. It is not a stretch to note the
> curvature of the hand bones in A. afarensis and the intermembrial
> index and compare it w ith living arboreal apes.
I really wish this could be more quantitative. How fast do selection
factors straighten the hand bones? The bones don't straighten
as soon as an environmental factor forces the animal to live away from
the trees.
(Regarding EVIDENCE, do you believe the sun will rise before it happens?:-)
> >> Therefore, even if we find the fossils of such apes we have
> >> no way to know they are aquatic apes.
> >> So you see, this is not just posturing about definitions and words.
Oh, I guess I did misread you a bit.
Then it is possible that Lucy and the first family are
"aquatic apes"?
(Please apply literary sense to the words "aquatic apes")
Tom Clarke
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