Re: AAT Theory
H. M. Hubey (email@example.com)
1 Oct 1995 17:58:21 -0400
firstname.lastname@example.org (David L Burkhead ) writes:
> Actually, no. Not one reason. Rather a whole suite of forces
>that, in toto, combined to drive human evolution to its current state.
>There are several things humans are _very_ good at. We are tool
All the hominids of which I have knowledge were also tool
We are social animals (allowing us to gang up on
OK. so are dogs, wolves, lions, even cape buffalo have been
known to gang up on lions.
when you can see those predators coming and when they can
>be intimidated by numbers in potential prey, both traits lacking in
We are superb at doing extended exertion under high
Can we run down animals like hyenas and wild dogs?
There is a trade for this last one, of course, in
>that we expend a lot of water for that.
However, with the
>availability of waterholes (which _are_ found on the savannah) we can
>function effectively at times of the day when most other animals have
So what does this have to do with bipedalism development on
land? It seems that we'd need to be hanging around water holes
all the time.
> "Gradual" is in the eye of the beholder. "Overnight" in
>evolutionary terms (a la "punctuated equilibrium") is still on the
>scale of thousands to tens of thousands to hundreds of thousands of
OK. So what? We know all this. It's relative. Are you implying
that you've run some kind of a correlation-regression analysis
on some variables, time/duration being one of them, and are
holding out on us?
Why don't you tell us what you've discovered so that we can
stop using fuzzy linguistic variables.
>And the fossil record _is_ sketchy. It will always be sketchy since
>only by the most exceptional of circumstances do animals leave fossil
>records in the first place. So two finds, half a million years apart,
>would show the changes of that half a million years, which might seem
>a substantial, "sudden" change. That we don't see the intermediate
>steps doesn't mean that they weren't there.
So? Even if it weren't so the record would be sketchy anway
because of the bus-waiting problem.
> Such as? What time scale is involved? Note that small mammals
>coexisted with dinosaurs. I don't know whether they lay eggs or gave
Just give us the results of your internal (if you haven't really
done it) correlation-regression analysis and tell us
what makes you think/say that things don't happen "suddenly"
> Well, I don't know _any_ definition, scientific or otherwise,
>that considers "sudden" to apply to processes that took tens of
>millions of years. That's a long time even on geologic scales.
TEns of millions of years is short on a geologic scale which
stretches to 4.5 billion years. Don't you think?
> You keep citing that word "physics" as if it were some mantra.
Soft sciences are harder than the hard sciences. The most mathematical
of the soft sciences (economics) has already bitten the bullet. It's
impossible to find a writer on philosophy of science who doesn't
mention physics, for obvious reasons.
The language of science is mathematics, for obvious reasons. And
physics is probably the best example of a successfull science
anyone can produce. That's the reason it gets mentioned all the
time. As far as bone-eye-balling goes, it's in even a lower
state of science than economics. The reason being that there are
many more things that can be measured and made scientific than
in physics but it doesn't get done. That's the reason for all the
verbiage and silly arguments over words.
The first good start in this direction was D'arcy Thompson. We have
even better methods now but I don't know anyone who's doing any
work in this area. It looks like it's all talk, so far. And you
are one of the biggest perpetrators of heat/flame on this newsgroup,
as far as I can see.
>If you are making a claim that just is not supported by any data
>you've presented. If you want to claim that humans are more
>"streamlined" than apes, then back it up: show me your CFD results,
>or your measured CD vs Reynold's number tests.
Put on a fur coat and then go wading, swimming, dunking, diving
or any other kind of aquatic activity that you wish. I'm sure
you'll feel the difference in drag.
> Experimentally, transitional Re is about 500,000. For a human
>sized person _wading_ in water (upright posture), that equates to a
>speed of 4.8 m/s.
I've tried wading/running in chest deep water and I don't think
I ever got beyond 2 m/s. That means we can forget about turbulence.
But that's my guess, maybe you can wade/run faster in chest deep
water than 4.8 m/s.
I suppose if I had a fur coat on, it'd be a lot slower.
> And once again, you introduce a non-sequitor. Since streamlining
>is a function of shape, and since shape _is_ something we can largely
>determine from bone structure, it most certainly _can_ be resolved.
Yep. Make models and put fur coats on them and put them in
water and measure the drag. so far I don't see any reason to
change my mind that humans are more streamlined.
> Are you being intentionally obtuse? Our ancestors, those who
>would have _had_ to live _after_ any aquatic phase, did _not_ have
>the traits you seem to be citing as evidence of "streamlining" (coming
>down, basically, to our being longer and thinner than apes). If we
I've already explained it plainly. Longer legs and being taller
would have provided a survival factor against land animals. Lack
of body fur probably would have increased their speed in water
but I don't know how much since I've never done any experiments.
Besides, as you should have read by now, some variation of AAT
could still explain what this is about so as in all theories of
this type, the ideas keep getting patched up as evidence against
it piles up. So if you are asking people to stick to a single simple
point of view you are wasting your time. It's just as easy to
patch up AAT as the landlubber theory (probably). The whole idea is
to wind up with the most plausible scenario at the end of the
discussion (which might never end).
> Read below: Long digits developed prior to anything that could
>conceivably be this "aquatic ape." They exist in _every_ primate
>species of which I am aware--including monkeys, apes, lemurs,
I don't know about that. As you should have read by now I asked
1) whether mammals did not indeed have been aquatic. AFter all
giving birth in warm water seems even easier than dropping them
on land. The baby would have come out and wouldn't have to start
breating until it floated to the surface. It's already used to
"holding its breath". If this happened at the time when much
of earth was under water, then the water would have been warmer
since the ice caps would have been melted. And the mammals
could have had body temperatures approximating water temperature
at the time. Besides, much of the food would/could have been
in the water by then. Even now, sea life is abundant.
2) Apes could have been aquatic and could have developed
long digits (and maybe webbing) as a result of the aquatic
environment. That could explain the whole grasping development
to begin with. After all, without it you still have to explain
how something like a dog would begint grasp and develop talents
to use tools. It would be a lot easier in water; notice polar
bears and sea otters.
> And tarsiers and lemurs? They're primates too, of a type
>antecedal to both apes and hominids. Yet they, too, have the long
>toes and grasping appendages of apes and humans. Where do they fit in
> What are you trying to pull here? That anthropology can be fuzzy
>(and I would be the _last_ to dispute that, although others might),
>does _not_ give you license to use fuzzy _physics_. And your claim of
Physics isn't fuzzy, but this field certainly is. And it has
lot less excuses for it than, say, economics.
> No. You are armwaving away serious flaws with your theory.
Shit, as if this field is not "hand waving".
> Except that the species lying between humans and apes were short.
>They were not tall. Thus, either they never did get tall in the
so, that's the point. They got taller. And they could have kept
getting taller after they left the water too. But increase in size
seems more natural in water.
>that escape predators by fleeing into the water, do _not_ adopt a
>wading posture. I can't think of _one_ that does so. Also, in the
I guess four legged creatures that "wade" into the water have to
adopt a "wading posture". You switch between millions of years
duration and few seconds whenever it suits you. Do you expect a
four legged creature to stand up like a human, the moment it
jumps into the water? Besides it couldn't. In order for that
to happen, the hips would have to allow the legs to straigthen out
naturally. Otherrwise the rear legs stick out and rotate the
animal. That's the whole point about straightening out of the
pelvis after a long time.
I've seen chimps doing this more than once. Obviously, then,
>animals about the same size and brainpower of our hominid ancestors
>are capable of dealing with land predators. There is no evidence that
>they would be able to deal with aquatic predators.
So what. It would be useful only if the whole AFrican coast was
infested by crocs. All the rivers and lakes would have to be
infested by crocs too.