Re: AAT Theory

David L Burkhead (
2 Oct 1995 16:25:32 GMT

In article <44ooo9$> writes:
>In article <44ndmb$> (Clara N.
>Fitzgerald) writes:
>> (David L Burkhead ) writes:
>Actually, this is not my response, probably David's in response
>to a query by me.
[ 8< ]
>At this point you have a modern chimpanzee which has survived to the
>current day, what more changed to force the proto-hominid to go
>beyond the chimpanzee mode of existence?

No. You don't have a modern chimpanzee. You don't have the
adaptations for knuckle walking. As for what could have forced it go
beyond the chimpanzee mode of existence, any of a number of things
could have done so: stronger predation at this earlier stage (leading
to more emphasis on tool use as an effective strategy for dealing with
that predation) is one possibility.

>You suggest:
>> > Extensive tool use, then, as one of this animal's major survival
>> >adaptations, could be favored at the expense of other traits.
>As Clare notes, the progression seems to be
>common ancestor -> bipedalism (Lucy) -> tools (erectus)
>so the evidence seems to be that bipedalism precedes substantial
>tools use. Brain size does not increase greatly until after
>Lucy as well.
>If Lucy had been a knuckle walker so that bipedalism only
>arose later along with tool use, I could give more credence to
>your story.

You are both confusing purpose-built stone tools with the entire
class of tools. Even today chimps make and use tools. The tools are
usually wood, often little more than stripping the leaves off a stick
to sue to go fishing for termites, or a heavy stick used to beat off
leopards. Again, all I have suggested is a slight change in
_emphasis_ over chimpanzees.

>> > once bipedalism is established, other traits (such
>> >as Wheeler's results wrt heat rejection) can come into play. These
>> >traits allow access to niches that were not available before and the
>> >new niches would tend to push for greater improvement in the traits.
>With this I am entirely in agreement. I just think that the
>seashore is probably the ideal environment for bipedalism to
>become established - walk uprght or drown!

If the seashore is such an ideal environment than how come not
_one_ animal has _ever_ become bipedal from living in an aquatic
environment. Since you are using bipedalism as evidence for an
aquatic past, it is no fair to then use humans as your sole example of
a bipedal animal which became so because of an aquatic past. That
would be circular reasoning and fallacious.

David L. Burkhead

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