Re: The straw man.
David L Burkhead (r3dlb1@dax.cc.uakron.edu)
12 Oct 1995 00:50:34 GMT
In article <454665917wnr@desco.demon.co.uk> Elaine@desco.demon.co.uk writes:
>
>I've noted two new anti-AAT ploys. One is to rename it AAH or AAS. No
>hassle. A rose by any other name...Personally I'll stick to AAT because
>I@m used to it, but the other terms are equally accurate. Like any
Actually, the other terms are far more accurate. The AAH does
_not_ qualify as a theory. As a hypothesis, proposed as a possible
explanation for certain theories, perhaps, but not a theory. Now, it
would cinch it's hypothesis status if it actually made some testable
predictions--like predicting some skeletal changes to be found in the
fossil record that differ from those used to propose it in the first
place (i.e. if you cite bipedalism as one of your initial pieces of
evidence, you can not then turn around and "predict" bipedalism). Or,
if you want to stay within the realm of comparative anatomy, you might
want to predict some further "aquatic traits" (again, not those
initially used to draw the hypothesis) and compare how humans compare
in those traits both to aquatic mammals and _terrestrial_ mammals.
For instance, since, as others have posted (with references) this
"diving reflex" is found in other terrestrial mammals and the human
trait seems closer to the terrestrial than the aquatic end of that
spectrum and so is of less import that first claimed.
>other attempt to explain the differences between apes and humans, it is
>of course a hypothesis. It is of course a speculation. Renaming it is
>an attempt at philosophical pseudo-speciation, implying "What you are
>doing is qualitatively quite different from what we are doing." That
>is not the case.
Sorry, but you are wrong here. Words have meanings. In science
a hypothesis is one thing, a theory is another. Things may be fuzzy
at the borderline, but what did the man say? "The existence of grey
does not invalidate the existance of black and white." Or there's my
personal favorite: "A sufficient difference of degree is equivalent to
a difference of kind."
There's pure speculation ("coctail party theories"--the kinds of
things a scientist might propose at a cocktail party, but is not
prepared to seriously defend) at one end and scientific "laws" at the
other (Newton's three laws of motion as one example--no exceptions
verified in the entire history of humanity). AAh lies pretty far to
the former end of the spectrum and is nowhere near in the region where
it can legitimately be called a theory.
>
>The other is the charge that AAT constructs a "straw man" in the shape
>of the late savannah theory and attacks it because it is easier to
>demolish than the more solid and unassailable scenario which has
>replaced it. Rubbish.
>
>AAT's case against the savannah theory as presented in the 50's and
>60's was not that it did not accurately represent the ecologoical
>conditiond in Africa at the timr of the split. We now know that it was
>in fact inaccurate but neither side knew it then. The argument was that
>even if it was accurate, it failed to explain the main physiological
>differences between apes and humans i.e. it cannot be predicted that an
>ape moving to the grasslands would become naked and bipe=dal.
Perhaps you can explain just what this "savannah theory as
presented in the 50's and 60's" was? Provide references
please--complete references, you know, with page numbers and
everything? It might help if we know exactly what it is that you
_are_ refuting. It might distance you from "straw men" of the AAH
side of the picture (you know, that treeless, waterless,
savannnah--the one that's not a savannah, but a desert instead).
Also, why do you insist that an earlier theory must "predict"
something that the AAH does not predict either. If you want to
predict that a quadruped--any quadruped--making the transition to an
aquatic phase becomes bipedal, I'll be happy to list counterexamples
if you'll list even one.
>Now look at the new improved model. Nobody questions it is solider and
>more unassailable as a true picture of the the then environment. The
>question is whether it is less or more successful at explaining our
>physiology. The "straw man" gibe implies it is so much more successful
>that AAT cringes from the prospect of challenging it and scuttles back
>to the easier practice of attacking the late lamented savannah theory.
>
>That is the reverse of the truth. Savannah Mosaic is not more but less
>successful at explaining anything, The old ST claimed the hominids
>became different because they moved to a radically and dramatically
>different environment. It turned out not to be true, but at least it
>sounded highly plausible.
>
>Now the theory is that hominids diverged through living in an
>environment that was only marginally different from other anthropoids.
>They were still arboreal for part of, or most of, the time. No reason
>has been suggested why they would not have continued to interbreed with
>other arboreal offspring of the last common ancestor.
Um, so? Are you suggesting that _every_ major change in
physiology (and a good many not-so-major for that matter) comes from
something as radical as a total change in environment? You want to
talk plausibility, what's so implausible about a species, over time,
moving into a niche and gradually specializing to fill that niche
well? Humans are quite well adapted to the niche we find them in
through most of our history as a species. Since that niche also
extends back through the other members of genus homo, they too can be
assumed to have been reasonably well adapted to it.
Last time I looked there's no great shock involved in the
suggestion that one member of a family might actually specialize in a
mode of functioning that most members of that family have to some
degree.
>There has been no overt recognition that any of the explanations
>offered by the old savannah theory have been weakened or need to be
>abandoned or replaced. Wheeler's noonday ape theory continues to be
>trotted out for lack of anything newer or better, as an explanation of
>bipedalism although its raison d'etre has been fatally undermined. The
>new scenario, even as presented by Wheeler himself, assumes th first
>hominids not merely might have, but actually, did retire to the shade
>for a mid-day siesta.
"Noonday ape" is your own straw man--the actual premise is that
an upright posture allows functioning at times of the day (when the
sun is higher in the sky) when other animals are holed up/resting from
the heat of the day. That does not mean that we have to function the
_entire_ period. A mid-day siesta does not invalidate the premise,
since there can well be periods on either side of that period when
hominids could function while other animals are already/still holed
up.
And nobody that I've seen have suggested that this is the _only_
reason for bipedalism--just one of a package of reasons why any start
in that direction could have proven advantageous and continued.
Treating it as such is yet another straw man.
It's kind of hard to take seriously the word of someone who says
"I don't engage in straw man arguments" when the person is doing it
with the same breath.
>The supposedly unassailable new model theory offers exactly the same
>explanations as the old one - nothing new at all - but it attributes
>them to the necessity of occasionally crossing the open spaces between
>one patch of forest and the next. It apparently assumes that one
>subsection of the l.c.a. made a habit of crossing the open glades
>while the others stayed at home; and that they remained from the
>beginning genetically isolated from the tree-dwellers they left behind
>and the other tree-dwellers they encountered in the next patch of
>forest. It assumes that these excursions turned them into naked bipeds.
And why not? These kinds of things _do_ happen. It is no more
amazing than that wolves and coyotes, whose ranges overlapped in the
not too distant past, should have different behaviors and traits.
They have quite similar physical equipment _and_ are cross-fertile.
They can cross breed, and once in a while they _did_ cross breed (as
do wolves, coyotes, and dogs today). Yet they remained separate and
retained separate characteristics. Why do you find the idea of
proto-hominids doing the same so amazing?
>If it was hard to believe that a life of obligatorily scavenging a
>meagre living on the the savannah on a full-time basis would do that,
>it is very much harder to believe that life in savannah mosaic would do
>it. AAT has no need to attack obsolete straw men when the latest
>version is even more insubstantial, in terms of its explanatory power,
>than its predecassor.
First, who says anything about "meagre living"? The question, of
course, is "compared to what"? Returning again to the wolf/coyote
example, the coyote's primary diet of mice and other small animals may
seem "meager" in comparison to the wolf pack's pulling down full-grown
elk and bison on which to feast, yet the coyote continues to take its
own path. Perhaps the lower _risk_ in killing mice has something to
do with it. Or perhaps the coyotes are kept out of the prime hunting
ground for larger animals by the somewhat physically larger wolves.
Or perhaps any of a number of other things. The fact is they've taken
a path that works _for them_. There's no reason to assume anything
extraordinary for proto-hominids to have done something similar,
possibly for similar reasons.
I can come up with half a dozen reasons for shifting to open
ground off the top of my head. Perhaps some combination of them was
the "real" reason. Or perhaps something I _haven't_ thought of led to
the change. But even if everything I've thought of, and everything
the entire paleo-anthropological community has thought of is wrong
that _still_ would not be evidence for AAH.
Negative evidence for a competing theory does _not_ mean that
_your_ theory is right. You can _never_ support your theory by
arguing _against_ others.
David L. Burkhead
r3dlb1@dax.cc.uakron.edu
d.l.burk@ix.netcom.com
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