Re: AAT Theory

David L Burkhead (
2 Oct 1995 01:25:17 GMT

In article <> (H. M. Hubey) writes:
> (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.
>makes sense.
>>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.

But none of these are also tool users. And none of them have the
same level of social organization that humans, or even chimpanzees.
Chimpanzees, for instance, are not noted for ground speed either (in
comparison to humans), yet strangely they are able to deal with
predators. Chimpanzees don't _have_ to run from predators. From what
I've seen, it's usually the predators that have to run from the chimpanzees.

>when you can see those predators coming and when they can
>>be intimidated by numbers in potential prey, both traits lacking in

Big cats and other savannah predators can be driven off by threat
displays, particularly when a determined _group_ of animals points
long pointy objects at them (Big Cat type thought: "Your claws are
bigger than mine.") This kind of thing is seen in the interaction
between chimpanzees and leopards as just one example (one I've seen
with my own eyes).

And with crocodylians, forget what you see in the Tarzan movies.
In _every_ case of a croc or alligator attack that I've come across,
no one knew the beast was _there_ until it bit.

>We are superb at doing extended exertion under high
>>thermal stress.
>Can we run down animals like hyenas and wild dogs?

I don't know offhand about hyenas and wild dogs, but humans can,
and do, "walk down" savannah ungulates (antelopes and the like). And
in many parts of the world, humans are active and functioning at times
when other animals are holed up against the heat. You don't _have_ to
run them down when you operate in a "time niche" when they aren't

> There is a trade for this last one, of course, in
>>that we expend a lot of water for that.

So, that's to head off the claims oft made here in the past that
humans _couldn't_ have evolved on the savannah because we need so much
water to function in high heat conditions (implicit in that argument
is the assumption that there is no water on the savannah, a false

>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.

No, not "all the time." We just need to do what other savannah
dwellers do: stop at the waterhole a couple of times a day. As I
said, it's a trade. Since humans _do_ live on the savannah taking
_just_ that approach, it is clear that they _can_. There is no
justifiable reason for assuming our ancestors _couldn't_, particularly
when it's clear that _they_ lived on the savannah too.

As for what all this has to do with the development of
bipedalism, let's see. You have an animal with four limbs and
bilateral symmetry (which describes all the primates _I_ know of).
You start using tools. How _else_ are you going to free up at least
one limb to carry/wield those tools, particularly if the animal
_already_ uses bipedal movement as one of its movement modes (again,
seen in all apes). The upright, bipedal, posture has been
demonstrated (by _experiment_ and direct measurement) to have
advantages wrt heat stress. An upright posture gives one the ability
to see farther on the savannah, and spot predators coming farther away
(hard to do when those animals are concealed in the water, a la AAH).
Thus, this _combination_ of factors, all together, can form a very
strong push toward bipedalism once an animal has begun to take that

>> "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?

Well, if that's a fair question to ask me, then it's a fair
question to ask _you_. Or are you, also, one of those who want to
grant special privileges to AAH and not require as high a standard for
it as you require of everything else?

The point is that "suddenly" as used in terms of "punctuated
equilibrium" is not the instantaneous thing you were implying. If
you'll read some books on evolution, you'll see that even these
periods of "quick change" occur over thousands of years.

>>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.

"So?" So again "sudden" changes are often the results of an
extended period of gradual changes. You are using the term "sudden"
as if it meant (in evolutionary context) a week and a half. That's
nonsense. Sudden in this context means _thousands_ of years,
thousands of generations, with only small fractional changes from one
generation to the next.

>> 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"
>at all.

I see what you're doing with this "correlation-regression"
analysis. You're using a buzzword. Tell you what. Define what you
mean by "suddenly" and give me an example of something that developed
that way so we'll at least be sure we're attaching the same meaning to
the word. I doubt that we are.

>> 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?

Not when the first 4 billion of those years are essentially just
the "precambrian" and vast majority of rock strata that
paleontologists deal with are yet younger. Tens of millions of years
encompasses the entire mesozoic. It encompasses the entire time
_since_ the mesozoic. A few tens of millions more and you're dealing
with the first amphybians.

>> 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.

Well, if physics is so much "harder" a science than anthropology,
_don't_ use the fuzziness of anthropology as justification for
fuzziness in physics--as you have done hear with your misaprehensions
about fluid mechanics.

>>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.

I doubt it. A fur coat is not designed for water use. It
becomes waterlogged quite rapidly. You feel a _great_ increase in
_weight_ which will swamp your off-the-cuff estimation of drag.

Once again you rely on fuzzy physics.

>> 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.

That's just _it_. With a bluff body (such as a wading human),
you _want_ a turbulent transition. A turbulent boundary layer delays
flow separation which is _the_ primary cause of drag in bluff bodies
in incompressible flow. Humand _don't_ move fast enough to make that
transition so a rough surface, tripping to turbulent flow, will
_reduce_ drag exactly the same was as the dimples on a golf ball, or
the fuzzy surface of a tennis ball, do. Can you at least read _one_
book on fluid mechanics before discoursing on the subject, even a good
aero book (try Anderson's "Introduction to Flight" which has some good
introductory fluid mechanics in it)?

>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.

I really don't give a rip on what you believe. However, in
science, it is incumbent on those who _make_ the claims to provide the
evidence for them. You have provided none, despite repeated requests.
This leads me to suspect that you _can't_. Jim Moore, OTOH, _has_
provided data, and references, on drag reduction from furry surfaces.

>> 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.

You don't know _if_, let along "how much." You keep making the
claim of reduced drag as if it were a fact and you simply do not know
enough fluid mechanics to have a meaningful opinion on the matter.

And you are _still_ ducking the issue. We _did not_ have long
legs at a time _after_ any aquatic phase. The "long legs" we have now
developed from _land_ dwelling, _not_ aquatic dwelling. Thus they are
not, _cannot be_ evidence for anything wrt any AAH. If you want to
cite the development of long legs as "evidence" you can only do so by
simply assuming that they were developed without there being any
evidence of any post-aquatic ape having them. Well, you can "prove"
anything if you are aloud to make up your data.

>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).

That's not how one develops a theory. Books detailing "theories"
that do not make testable predictions (which means that they can be
shown to be wrong) are among the most worthless pieces of tripe anyone
ever killed a tree fore.

>> 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,
>>tarsiers, etc.
>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.

So sea life is abundent? So what? Also, the baby "wouldn't have
to start breathing until it floated to the surface." Beg pardon?
That's exactly backward. It wouldn't be _able_ to start breathing
until it got to the surface. Before you cite water as such a
wonderful place to give birth, remember that _most_ aquatic mammals
have their young _on land_. Of those I am familiar with, only those
that _can't_ return to land to give birth don't.

Thus, your hypothesis is contradicted by observation.

>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.

Once again, to go back far enough to have an aquatic ancestor be
responsible for long digits, you have to go back far enough that you
are no longer talking about _any_ kind of ape.

>> 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
>See above.

Yes, see above. If you are talking about an aquatic animal
ancestral also to tarsiers and lemurs you are no longer talking about
an aquatic ape.

It seems, however, that what you want to do is cite a bunch of
traits as being "aquatic derived" then postulate a common ancestor
through which those traits evolved, and then assume that all animals
which have those traits are descendents of that common ancestor, with
nothing more than the _assumption_ that the traits are aquatic derived
to support it. That's a pretty good example of circular reasoning,
where you assume your conclusion. You can prove anything that way
too. That's why it's a logical fallacy.

>> 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.

Physics isn't fuzzy, but your use of it to date _has_ been. And
when called on it, you retreat into saying that anthropology is a
fuzzy subject. Well, sorry but that pig won't sing. Whether or not
anthropology is a fuzzy subject (something about which I have my own
opinion) is no excuse for your continued treatment of physics as one.

>> No. You are armwaving away serious flaws with your theory.
>Shit, as if this field is not "hand waving".

You might want to learn a bit about the field first. Sure,
there's a lot of hand waving there (I'd be the _last_ to deny that!)
but there's a lot of careful, meticulous research and solid foundation
too. But it sure is nice to be able to use the former as an excuse to
ignore the latter isn't it?

>> 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.

So the point is that human tallnes is _not_ evidence for an
aquatic phase since it _didn't_ develop in the water. It is not, and
cannot be. And if you move the aquatic phase back far enough to be
the ancestor of tarsiers and lemurs as well (as you implied up above)
then you have to deal with an aquatic animal whose size is measured in
a couple tens of _inches_ tops (check the _size_ of those early
primates). Any "theory" that relies on such blatant contradictions is
no theory at all. It doesn't even qualify as a good hypothesis, or a
mediocre hypothesis.

>>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.

So the only habitually wading animals in existance now are those
that have taken up the habit in the extremely recent past? That seems
to be what you are saying: that they've not had time to develop the
traits that you apparently assume _must_ be good. Once again, you can
prove anything if you are allowed to make up your data.

>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.

Do you _read_ the posts on this subject or just look for
snippets to take potshots at? I belive it was Jim Moore who cited
sources wrt fossil evidence that crocs _did_ infest every body of
water of significant size that we've identified from the period. You
can, of course, just assume that by some majic _one_ lake, large
enough to serve as a haven from land predators (many of whom can swim)
remained clear of crododiles and their relatives. You can make up
that point, sure. You can prove anything if you are allowed to make
up your data.

David L. Burkhead

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