Re: Bipedalism in different substrates

From: Algis Kuliukas (algis_at_RiverApes.com)
Date: 08/23/04 

Date: 22 Aug 2004 20:30:09 -0700

"Rick Wagler" <taxidea3@shaw.ca> wrote in message news:<3dJVc.164775$M95.102748@pd7tw1no>...
> "Algis Kuliukas" <algis@RiverApes.com> wrote in message
> news:77a70442.0408200142.5fd12a42@posting.google.com...

> > Safer: Even in depths up to waist deep it is safer to wade than to
> > swim if the water is, you know, moving. (Flowing rivers, coastal
> > waves, tides etc) In depths deeper than waist deep it could still be
> > argued that it's safer to wade if you can because at least then you
> > can keep track of the depth of the water you're in and see if you are
> > getting out of your depth.
>
> Safety is not an issue. Animals are endlessly ambitious and
> are without fear. Developing bipedalism as a means of guaging
> depth makes no sense. Why is depth an issue for a swimmer?
> If it is a non-swimmer what possible reason has it to be in water
> of a hazardous depth so often as to necessitate such an extreme
> evolutionary response? As for being in currents so strong as to
> be impossible to swim against being bipedal is not really going
> to be of much use. Useful for what? Maybe you can dig your
> feet in and hold your position and not expend the energy that
> swimming involves but what behaviour or activity would necessitate
> such a thing to the extent that it would activly select for bipedal
> behaviour? And wouldn't being quadrupedal in such a circumstance
> be more efficacious? As I said animals are without fear but they
> are risk-averse. Fear of getting in too deep is not an issue if
> you can swim. There is no 'too deep'. But plunging into a
> powerful current -why???

'Animals are .... without fear' - are you serious? Apes are poor
swimmers therefore they probably have a real and justifiable fear of
water. That's probably why they *do* wade bipedally - in Conkuati
chimps, even when the water is up to their shoulders.

Fear of getting in too deep might not be an issue if you are as
aquatic as a seal, but for those mammalian species (like hominoidae)
which are not very adept it is a real issue. But you just wish it away
with a flick of your wrist as if it did not exist.

> > I know that swimming is faster than wading at depths greater than
> > waist deep but there's more to it than just speed, right?
> >
> Sure. But the point remains that swimming is the overwhelming
> choice when it comes to dealing with water. This ape of yours
> augments it with bipedalism. Why? An ape will go bipedal in
> these circumstances - sometimes - because it can not because
> it must.

If the animal is small and/or the water is deep then, yes, swimming is
the usual response but if relatively large apes find themselves in
strips of woodland surrounded by relatively shallow standing water,
this is not the case, right?
 
> > Swimming is bound to be a riskier mode of locomotion than not
> > swimming, agreed?
>
> No.

NO? - What is the point of discussing these issues if you are so
bleeding stubborn you cannot even concede such a point? For a
terrestrial animal swimming *must* be riskier than not swimming. I
know all people are capable of twisting whatever evidence is presented
to them into a form that meets with their own pre-conceived ideas so
as to delude themselves that they are right, but you aquasceptics are
particularly adept at it.

> Swimming is riskier only because it allows an
> animal to ignore depth and, sure, on occasion this will
> lead to disaster but so often as to, on at least one
> occasion, lead to an extraordinary selection of
> characters to largely dispense with the need to swim
> or to chain this animal to relatively shallow depths?

Apes, generally, are poor swimmers. So - as you guys keep reminding me
- are we. Therefore swimming is riskier than not swimming for a
hominoidae, right?

> This is an extraordianary claim and you should at least
> try to back it up. If all you are saying is that bipedal
> wading can, at times, be the preferred option I can
> certainly agree with this but you are claiming much,
> much more without, seemingly, realizing that you are
> doing so.

So - arguing that swimming is riskier than not swimming in hominoidae
is an "extraordinary claim"? Blimey.

See how even this first, simple logical step on my list has to be
challenged vehemently? Can't you see how this rabid anti-AAHism has
left you devoid of all common sense?
 
> > So, if a hominin has to cross a stretch of water and
> > it can avoid swimming by wading then it is more likely to survive.
> > Still with me?
>
> Nope.

What a surprise. No, any argument that claims that water played *any*
specific role in human evolution must be resisted at all costs. Such
fanaticism. It's so peculiar.

> If it can swim then it is not going to drown in
> wading depths.

But apes are not very good swimmers, right? Even humans are not very
good swimmers either, but we're better than apes.

> If it gets too deep it must swim or turn
> back. So what is achieved. At depths where it is
> possible to both swim and wade the risk of swimming
> is for all practical purposes nil.

Practically nil is still greater than nil. Over an evolutionary
timescale this would get translated into meaningful selection. It is
not black and white. Some risk is greater than no risk. Chimps and
children have been known to drown in shallow water. Blimey, I thought
that was one of you guys' key arguments against the AAH. If our
ancestors were exposed to that kind of risk more than their's (chimps)
why is it so astonishing that we would evolve modest traits to help a
little in those areas?

> That's why people learn to
> swim in the shallow end. It can only avoid swimming by
> wading by never going to those places that only swimming
> can take you. Your image of the super cautious wading ape
> just makes no sense. If this animal is going to exploit aquatic
> habitats to the degree that this activity led to the selection
> of every major anatomical and physiological difference
> between humans and modern apes then Hagstrom's
> merpeople scenario is the much more sensible speculation.
> Really, Algis, you should have the courage of your convictions.

Again - this notion that in order for the selection to be real it has
to be extreme - why? I ask again, what selective pressures, in a
single generation, drove encephalisation? It clearly happenned but can
you define, with any precision, exactly how a slightly bigger brained
individual had selective benefit over a slightly smaller brained
individual in any given lifetime? Come on - think about it. Apply the
same level of scepticism to that as you do to the wading idea. Now see
how the wading idea, in comparison, is so easy-peasy and clear cut?
No, I don't suppose you will see it that way.
 
> Therefore traits which make hominins better waders are
> > clearly going to be selected for if individuals have to cross
> > stretches of water, even only ocasionally.
> >
> What makes a better wader? When you hit the water just
> keep going. A biped is no better or worse a wader than
> a quadruped

What makes a better wader? Duh. The same kind of things that make for
better quadrupeds, bipedal walkers, swimmers, flyers, burrowers: more
efficiency, more speed, more power, more stability - you know....
better.

A biped is no better or worse a wader than a quadruped? But which
quadrupedal mammals wade bipedally? Oh - its just the apes. Just a
coincidence that, eh, Rick?

Bipedal wading in waist deep water imposes exactly the same weight
bearing strains on the lower back and pelvis - that would clearly act
as forces of selection - as does terrestrial bipedalism. It imposes
slightly less weight bearing stresses on the knees but in knee depth
water (where apes still tend to move bipedally) those weight bearing
stresses would again be nearly identical to terrestrial bipedalism. If
you can accept that terrestrial bipeds are better at bipedal
locomotion on land than a quadruped (can you even do that, Rick? - I
expect that you'd have to deny it too - can't be seen agreeing with a
AAT net loon on anything can we - you'd probably get expelled from the
party!), why is it so very difficult for you to accept that bipedalism
in water would have any effect at all? Don't tell me... - 'It just is.
It's water, right? And water played no part in our evolution because
that's what I've been taught and that's what we all think here, so
*** off with your AAR!'

> > Which part of that logic is wrong?
> >
> Your premises...which is to say grant me my premises and
> I can make an elephant fly....

Oh sure, it's *me* whose doing the twisting, right. Note that you
could not even accept my first premise that swimming was riskier than
not swimming.
 
> > I know that you must find fault with it somwhere, otherwise you'd have
> > to disagree with your pal NAS and we can't have disagreement in the
> > ranks of the 'slightly more open woodland than chimp habitats but
> > slightly less open than savannah ecotone' club.
> >
> Since Norm and Jason and Bob and Mike and --GOOD GOD
> ALMIGHTY!!! ....Paul???? make so much more sense when
> dealing with you why would I disagree.

Oh well, if this is the criterion on which you judge whether a
hypothesis is valid or not, no wonder.
 
> As an aside where are you getting this Med-Tethys shoreline
> business re hominoid apes??

Oreopithecus - perhaps contemporaneous with the LCA, if not on the
same line as Hominins.

Paleogeography of Miocene ape sites (Several European locations.)

Paleogeography of the Me/Tethys coastaline around the mid-late
Miocene.

It's called putting two and two together: African Hominoidae are
likely to have lived in such coastal habitats.

Algis Kuliukas