Re: Bipedalism in different substrates
From: Algis Kuliukas (algis_at_RiverApes.com)
Date: 08/07/04
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Date: 7 Aug 2004 06:21:36 -0700
NA Sides <nas@sonic.net> wrote in message news:<n2ksg0ph2ckg624bsr8uh63bltcpqdr7ad@4ax.com>...
> On 30 Jul 2004 20:43:25 -0700, algis@RiverApes.com (Algis Kuliukas)
> wrote:
[snip]
- Part Two
> Unfortunately, even in the unlikely eventuality that you can someday
> show that such a niche could have existed, you will continue to run up
> against the embarrassing fact that, if proto-hominins were generalists
> foraging in a variety of areas and employing different foraging
> strategies, and if they were foraging quadrupedally on land and in
> trees, the selection for quadrupedal traits would outweigh any
> selection for bipedality that might lead to enhanced water-based
> foraging. Your only realistic option would be to have them foraging
> bipedally both on land and in water, but this would shoot down your
> claim that wading was the primary "causative factor" for bipedalism,
> so you can't do that without abandoning the faith.
That's just nonsense. First of all, it's not an unlikely event.
Wetland habitats are here and they always have been. As 3 out of 5
extant great apes feed in such habitats today, at least sometimes,
it's doesn't take a great stretch of the imagination (at least for
those of us who possess such a thing) to envisage a scenario where
hominoid ancestors could have done so *more*. Add to that imagination
the facts that Miocene apes of Europe & SE Asia must have lived around
the Med/Tethys coast and that Pliocene hominins of E Africa certainly
inhabited riparian forests prone to wide flood/dessication cycles and
that pushes it enough in the direction I'm talking about.
A generalist - by anyone's defintion but your own - means more aquatic
than an arboreal primate but I understand that would be just too
controversial to contemplate for some of you guys. So 'generalist' to
you, in reality, just means 'not arboreal'.
All primates and especially more generalist apes have all sorts of
pressures on their locomotor repertoires. I'm suggesting that as
wading is the most likely to induce bipedalism, then any generalist
that practiced *more* wading would, undoubtedly, practice more
bipedalism. It wouldn't take much extra wading to push apes over a
threshold where they moved bipedally on land too.
> >> >> > I'm certainly ignorant of any evidence exists that hair reduction
> >> >> > decreases drag. If you know of any such evidence could you cite it?
> >> >> > And if you don't know of any such evidence, could you stop asserting
> >> >> > that it does?
> >> >
> >> >So evidence showing reducing hair by 100% gives 11% reduction in drag
> >> >in humans doesn't count, right?
> >>
> >> Yep. It counts. If you can present any evidence that human ancestors
> >> lacked any trace of body hair, then you might have a point. But it
> >> appears that hairy ol' unshaven male swimmers experience no more drag
> >> from that cause than do unshaven females. So you don't have any point
> >> until such time as you can provide experimental data that suggests
> >> otherwise.
> >
> >You're clutching at straws.
>
> If you know of evidence that women's less dense body hair does provide
> them with a relative advantage over men in terms of drag reduction,
> I'm more than willing to consider it. You haven't presented it yet.
Until someone does that experiment which actually measures the body
hair that's been shaved off and tracks the drag reduction as the hair
regrows we just don't know. But, 100% body hair reduction does give
around 11% drag reduction in water. It's interesting that you seem to
have convinced yourself that this an argument *against* the part of
the AAH explanation for human nakedness that suggests it was to help
our swimming abilities (another part, which you always conveniently
forget about, is of course that it aids water-powered sweat/dip
cooling.) Self-delusion knows no bounds.
> >> >> > Jason has pointed out that you don't have a model. You haven't even
> >> >> > begun to gather the data that might eventually allow you to create a
> >> >> > predictive quantitative optimum foraging model.
> >> >
> >> >Ooooh. There's a big term. And can you point out to me, please, in the
> >> >literature - an exact citing would be nice - of *any* of the twelve or
> >> >so models of hominin bipedalism which have done this. Because I can
> >> >see that it's sooo important, all of a sudden. Did Lovejoy do that?,
> >> >Hunt? Wheeler? Rose? Anyone? I don't think so. So - WHY - is it that
> >> >the wading model has to do so? Gosh, it wouldn't be yet another case
> >> >of double standards, would it?
> >>
> >> I don't know what anyone else has done in this respect, but it
> >> wouldn't be difficult to apply standard optimum foraging models to any
> >> scenario which posited a proto-hominin ecology not that different from
> >> chimps.
> >
> >'It wouldn't be difficult' and yet no-one bothered to do it. Still,
> >you require me to do so before you allow your mind to be openned to
> >the outrageous possibility that hominins moved through water much.
> >Can't you see how this argument wreaks of double standards?
>
> I have only your word that no one has done it. Have you exhaustively
> researched the relevant literature?
I've read all the major relevant papers on bipedal origins and I don't
know of a single mention of 'optimum foraging strategy' or any general
attempt to justify their model in such precise terms. I put it to you
that as you are the one suggesting that this is so important a
requirement, all of a sudden, you point me to some model of bipedal
origins that has done so, so that I might try to emulate their high
standards. I suspect, however, it is just yet another case of double
standards.
> But even if no one has applied
> optimal foraging models to their scenarios, this doesn't mean much if
> the scenario posits an ecology similar to ecologies that we know, from
> studies of modern humans or apes, can support populations of
> hominoids. Do you get it?
So, you're covering your arse, already. I see. You must realise
already that you're just being hypocritical requiring that the wading
hypothesis fulfills this requirement, then.
Extant apes (bonobos, w l gorillas and orang utans - that's 3 out of
5) live in wetlands, at least some of the time - and so do many
humans. I've just come back from the excellent Museum of Western
Australia, here in Perth, and I was interested to read that Perth city
centre is built on a former wetland zone on the banks of the river
Swan. Apparently the very area where the city centre is was used for
thousands of years by the local Noongar people for foraging for food
because it was so rich in wildlife. This is, remember, just 170 years
ago. Of course all over the world people have done the same thing but
you're too blinkered to see it.
> You're the only one positing a radically
> different niche from any that we know exist.
No.
a) it's not so radically different, is it? Why do you gape in horror
at the prospect of humans and apes getting their toes wet to get food
and to keep cool from time to time? Look at a population density map
of any country in the world and look where all the cities are.
b) They do exist and they always have.
> We know, in fact, that no
> hominoids, and not even monkeys, exploit aquatic resources in the way
> you claim proto-hominins did.
Rubbish. Gorillas wade, bonobos wade, chimps wade, orang-utans wade
and humans wade. Gosh that covers all of them. It's just a question of
degree. I'm proposing that our ancestors waded *more* than theirs did.
Get it?
> It's incumbent on you, therefore, to
> support your claims that an adequate resource base exists and that
> hominoids could only have accessed those resources through wading.
Bonobos today in the Congo have been documented wading bipedally for
algae in shallow pools and have been reported wading bipedally whilst
foraging in streams too. Western lowland gorillas have been reported
wading bipedally whilst navigating flooded beis (swamps) in the Congo.
If extant apes can do this today why do you doubt that their (and our)
ancestors could have done so in the past? If their wetland habitats
where more dominant that those in the tropical rainforest of the Congo
today - such as coastal/island/river delta forest on the Med/Tethys
coasts in the Miocene - you know where Miocene apes must have lived as
they passed to/from Africa to Europe - and if riparian forest in East
Africa were inhabited by their descendants in the Pliocene - where the
water's edge/area ratio would have been much greater than the Congo
wetlands - then WHY, apart from wishful thinking on you part - can you
not accept that their ancestors must have been exposed to greater
selection from moving through water than extant apes today?
> >> Both chimps and human hunter-gatherers were utilizing known
> >> resources in known ways. The proto-hominins may have employed novel
> >> foraging methods, but if the scenario merely posits increased
> >> distances between resource patches, then not much extrapolation is
> >> needed. You probably could apply with little modification the same
> >> sorts of models that are applied to human h-gs.
> >
> >How does this contradict the wading model? Why does this 'increased
> >distance' (based on the bizarre notion that trees would have just been
> >ever more thinly spread out, as opposed to clustered around water
> >sources) imply bipedalism? And why is that no problem for the foraging
> >strategy but if they stepped into water it would be?
>
> Who said the resource patches must be individual trees? If clumps of
> trees become separated due to increasing aridity, then the distance
> between clumps becomes a factor. These clumps wouldn't necessarily be
> all clustered around open water sources. You'd have broken and clumpy
> forest margins merging into woodland-grassland mosaics.
Not *necessarily* but overwhelmingly likely. The vast bulk of evidence
is that tree cover is highly correlated with the water table. This is
itself highly correlated with precipitation (including that from
higher altitudes) and, of course, proximity to water courses. Any
ecologist knows this. Gallery forests are well known to act as refugia
for flora and fauna species in times of aridity. (See, e.g. Meave et
al 1991)
Meave, Jorge; Kellman, Martin; MacDougal, Andrew; Rosales, Judith
(1991). Riparian Habitats as Tropical Forest Refugia. Global Ecology
and Biogeography Letters Vol:1(3) Pages:69-76.
Orang utans live in very lowland, swampy forest *because* that is
where most of the fruit trees grow. The species diversity there is a
function of the proximity to water courses and precipitation. See, for
example...
"... Even in the lowlands the orang-utan is not evenly distributed. A
review of the available literature on orang-utans, supplemented by
survey data from many different sites in Sumatra and Borneo (Rijksen,
unpublished), indicates that the ape is more commonly found close to
streams, rivers and in swamps; it is found in greater densities in
(alluvial - deposited by running water) forest patches in river
valleys, and in the (flood-plain) peatforest near swamps or between
rivers. One is less likely to come across the ape in any numbers
further away than 10-15 km from a watercourse or a swamp with open
water. No doubt the main reason for such preference is the higher
incidence of preferred fruit trees close to rivers, but an additional
reason may be that rivers and streams are the best geographical
landmarks for spatial orientation. It seems that the ape is as rare or
absent in extensive, relatively uniform lowland forests on well
drained 'dry' flat ground, as it is in some mountain complexes above a
certain altitude." Rijksen & Meijaard (1999:68.)
Rijksen, H D; Meijaard, E (1999). Our vanishing relative. Kluwer
Academic Publishers (Wageningen)
> If bipedalism
> allowed penetration into the more open habitats, perhaps because it
> allowed for weapon carrying and the porting of tools and foods, then
> bipedal traits would be favored. It's no problem for terrestrial
> scenarios because there would have been no great change, at least
> initially, in foraging strategies - just a gradual penetration, over
> periods of many generations, into the more open habitats. No radically
> different ecological relationships would be presumed. You, on the
> other hand, are positing a wading-based niche that doesn't exist now
> and without evidence that any such niche ever existed. .
This is a bizarre concept: bipedalism *allowing* weapon carrying.
Perhaps this is part of your problem. You seem to imagine these apes
'wanting' to carry weapons before the advent of bipedalism. For twenty
million years they wanted to but were prevented from doing so by their
damned ancestry. Finally, they broke through. Evolution, with magical
prior knowledge of the advatnages that would follow, 'broke through'
and bipedalism was finally achieved *allowing* them to carry things.
Perhaps I've misrepresented your point of view there, but I think it's
instructive that you use the word 'allow'. You see the wading model
needs no such concept because in water they move bipedally - as a
matter of course.
So, taking away this 'desire' to be bipedal so they can carry weapons,
please explain why on earth an ape 'penetrating more open habitats'
would start to move bipedally? Can you give me a tiny scrap of
evidence from any extant ape that supports this? I think you'll find
that the evidence is for quite the opposite view. Chimps live in more
open habitats than bonobos but they're the ones with traits which
indicate less bipedality.
"Morphological differences between chimpanzees and bonobos, including
more centrally positioned foramen magnum (Shea 1984), longer thigh
bones (Zilhman 1984), lower intermembral index (Coolidge & Shea 1982;
Napier and Napier 1985), heavier lower limb muscle (Zihlman 1984),
loner feet (Fleagle 1988) and different distribution of body weight
(Zihlman 1984) have led to the claim that bonobos demonstrate a
greater predisposition for bipedal locomotion (Susman 1987). Myers
Thompson (2002:66) Also, she doesn't note that bonobos have more
anteriorly flared iliac arches.
But never mind the evidence, eh Norm - you stick to your guns mate!
Bipedalism happenned on the open plains of Africa. Dart is dead, long
live Dart!
Wetlands do exist now, they always have and hominoid and hominin
ancestors almost certainly were *more* exposed to them than extant
great apes are today.
[..]
> >> The point here is whether there might have existed a viable
> >> specialized wading niche potentially exploitable by apes. You have
> >> presented no evidence that any such niche existed or could have
> >> existed.
> >
> >Yes I have. bonobos, w l gorillas and orang utans exploit such
> >habitats today - at least some of the time. Therefore if their habitat
> >changed to have *more* exposure to wetland and less tropical rain
> >forest - they're almost certianly going to survive. It's just mock
> >personal incredulity again. It's all you have. Pathetic.
>
> Try to calm yourself, Algis. Maybe you'll be able to think more
> clearly. I'm going to explain this again. Bonobos, gorillas and
> orangutans wade occasionally but no extant ape occupies any sort of
> wading-based niche.
That's right. That's why.... wait for it.... they're not bipedal like
we are. That's the point.
> Bonobos, gorillas and orangutans don't provide
> support for your claim that such a niche once existed. If anything,
> they constitute counter evidence. If such a niche could exist in areas
> they inhabit, then populations of their ancestors had plenty of time
> to exploit that niche. This never happened, and it constitutes
> evidence that there exists no sustainable resource base in ape habitat
> that could have supported a wading-based species ecology.
What? Such niches *do* exist in areas they *do* inhabit and they *do*
exploit them. IT DOES HAPPEN. The claim is that our ancestors did so
*MORE* than they do today. The claim is that the habitats on the
Med/Tethys coast exposed the ancestors of the Hoominoidae to greater
wading pressure resulting in an 'aquarboreal' (wading/climbing)
ancestor for all great apes. Their descendants that came to Africa
either settled in the tropical forests to the west (as their habitats
became *less* exposed to wading they became *less* bipedal) or in the
east (as their habitats became exposed to wide fluctations in climate
their riparian habitats continued, in fact intensified, their exposure
to wading and ultimately to tree loss).
> >> Some mammals, including apes, do forage in water for aquatic
> >> resources, but they tend to fall into two classes: generalists and
> >> specialists. Generalists can utilize a wide resource base and some
> >> species can forage arboreally, terrestrially and by wading or
> >> swimming. All evidence I'm aware of supports the idea that our own
> >> ancestors were in fact generalists.
> >
> >Yes generalists that left the trees but didn't take one step in the
> >water. Doesn't sound much like a generalist to me.
>
> As much as possible, you should try to keep track of your
> corespondents' real arguments and positions, not strawman versions
> that you yourself make up. You haven't done a very good job of that in
> this thread. No one has said that proto-hominins "didn't take one step
> in the water." In the very paragraph you supposedly were responding to
> I say that some mammals, including apes, do forage in water for
> aquatic resources. Don't you think that should have provided a clue?
> I've said that proto-hominins were probably generalists who foraged
> primarily terrestrially, but also arboreally and perhaps to some
> extent also in water.
Ok, I apologise. 'didn't take one step' was an exageration. But then
answer me this this... if you accept that as generalists they did move
through water sometimes and, to be precise, more than did the anestors
of the apes and, presumably, you agree that whilst doing so they were
bipedal pretty much all of the time - why then do you resist the idea
that this extra wading might have contributed in any way to the
evolution of hominin bipedalism? Aren't you flying in the face of the
laws of natural selection?
They waded more, they were more bipedal but somehow this extra
bipedality just didn't count. *Other* factors must have been the
cause, and *not* the wading, right?
> >> Proboscis monkeys and long tailed
> >> macaques seem to be the only primate species who can inhabit mangrove
> >> forests. The proboscis monkey is a specialized leaf eater that is more
> >> or less restricted to mangrove forest by its own dietary
> >> specializations while the long tailed macaque is an omnivorous
> >> generalist who can live not only in mangrove forests but in a variety
> >> of other habitat situations. In almost every respect except size, we
> >> are more similar to the long tailed macaque than to the proboscis
> >> monkey. Our generalist ancestors wouldn't have been restricted to
> >> mangrove forests. I've pointed this fact out to you previously and
> >> you've ignored it. Also hominins are morphologically adapted to
> >> bipedal striding; not wading or swimming.
> >
> >Once again - I've never said they were *restricted* to any habitat.
> >I've pointed this out to you hundreds of times but -again - you ignore
> >it.
>
> Yes, and I've repeatedly pointed out to you a contradiction between
> your claim that wading was the primary "causative factor" of
> bipedalism and your other claim that proto-hominins were generalists
> who weren't restricted to a wading-based foraging strategy. If
> proto-hominins were inhabiting different habitats during certain
> phases of the Miocene climatic fluctuations, and if they were foraging
> quadrupedally in trees and on land, then selection for quadrupedal
> traits would wipe out any bipedal traits that interfered with
> efficient quadrupedal foraging and defense behaviors.
Why? Extant great apes are pretty much quadrupedal in their usual mode
of terrestrial locomotion 97% of the time. It doesn't stop them moving
bipedally when they're in water and it doesn't stop them moving
bipedally sometimes (about 3%) on land too. Surely, if an ape moved
through water more and therefore it was more bipedal generally, it
would be more likely to move bipedally on land too. It's this
correlation, which you have to pretend would not apply, which is the
clinching argument here. Bonobos (cf chimps) provide very strong
evidence of such a correlation.
> >I agree that we are generalists and that our ancestors were too. But
> >you see that's a problem for you because being generalist means, by
> >definition *more aquatic* and 'more aquatic' is all Hardy was ever
> >talking about, right? It's all I am arguing for - as I've made clear
> >at least a hundred times.
>
> Being a generalist doesn't necessarily mean "more aquatic."
Well it does if we're talking about a more-generalist-than-a-chimp
type of ape, which i think we are. You're contradicting yourself. A
moment ago you were claiming that of course you too agreed that our
ancestors moved through the water somtetimes - now you're... what are
you claiming?
> Chimpanzee-like hominin ancestors would already have been relatively
> generalized, foraging mostly in trees but also on the ground and to
> some extent in water. Bipedalism may simply have allowed their
> descendants to inhabit the more open habitat that was gradually
> replacing large areas of what had been deep forest.
This 'allowed' word again. Why on earth, tell me, does quadrupedalism
'prevent' or even slightly inhibit any move towards more open
habitats? Is there *any* evidence for this? No - not one jot. The more
open the habitat, the more committed the quadruped, in fact. It is in
trees that upright posture is promoted and it is only in waist deep
water that bipedal locomotion is guarranteed.
This notion is a pure fantasy. You really are clinging on to the
savanna theory even now in 2004. Amazing.
> Coatimundis,
> coyotes and English sparrows, for example, are relatively generalized
> non-aquatic species, though like any species they have their own
> species-specific characteristics.
We're talking about apes.
> >Your generalists, though, bizarrely never exploited any aquatic
> >resources at all. Your generalists left the trees but only moved onto
> >the more open grasslands to, presumably, explout a purely terrestrial
> >hunter-gatherer lifestyle. Some generalists, those.
>
> Is it an organic memory deficit, unconscious repression, or do you
> deliberately attempt to ignore and forget what people actually say? If
> I repeat a few dozen more times that I think proto-hominins probably
> sometimes foraged in water, do you suppose the information will begin
> to penetrate your brain? Perhaps you could tape it to a corner of your
> monitor screen. I'm going to try to say this clearly. Please try to
> focus this time. Generalists can exploit a wide variety of habitat
> resources. Proto-hominins probably still foraged to some extent in
> trees and also sometimes in water.
But you just said: 'Being a generalist doesn't necessarily mean "more
aquatic."' Ok then. I accept you accept that proto-hominins foraged in
water sometimes. Great. So, did they do so more than the ancestors of
apes? Yes or no? Did they do so bipedally? Yes or No?
> >> >We're talking about bipedal origins right? I mean - 6 million years
> >> >earlier. Where's the pedenatic menu there and the detailed foraging
> >> >model specification? Oooooh - not there is it? Oooops.
> >>
> >> You've been given a list of foods that are or have been exploited by
> >> both chimps and human hunter-gatherers. No great extrapolation is
> >> necessary to derive a plausible resource base that could have
> >> supported proto-hominins. If they were occupying slightly more open
> >> habitats than is optimal for chimp-like deep-forest dwellers, then the
> >> same optimum foraging models can be applied without much modification.
> >> Just increase the average distance traveled between resource patches.
> >
> >And what about the marine food chain? When did that come in?
>
> You tell me. This is your area of interest.
Ever heard of omega 3 essential fatty acids - heavily implicated in
healthy human infant brain growth? They are largely found in the
aquatic food chain?
> <snip>
>
> >> If proto-hominins were ecologically similar to chimps, then present
> >> models can be applied with small modifications. You, however, are
> >> claiming the existence of a wading-based niche in mangrove forests.
> >
> >Why chimps? Why not bonobos? Bonobos appear to be, at least on a
> >trajectory towards bipedalism compared to chimps. And where do they
> >live? In wet and wooded habitats.
>
> Both chimps and bonobos subsist mostly on fruits and terrestrial
> herbaceous vegetation. They both are quadrupedal knuckle-walkers and
> facultative bipeds. There's no evidence that either is "on a
> trajectory" toward obligate bipedalism. If a subpopulation of bonobos
> were going to become bipedal, they've had more than adequate time to
> do so. It never happened.
Of the two, it is the bonobo that anecdotally (e.g. de Waal & Lating
1997) or anatomically (see above quote from Myers Thompson 2002) is
the more bipedal. It is the bonobo which has less fear of water and
greater exposure to the need to wade. But, of course, this extra
pressure has still been sub-optimal to cause a switch to fully
obligate bipedalism. Our ancestors, it is argued, had still greater
exposure than the bonobo.
> >> You've presented no evidence that any such niche could have existed.
> >
> >Astonishing. Bonobos, w l gorillas and orang utangs *DO* live in such
> >habitats today - at least some of the time. Wetlands *DO* exist today
> >and before modern humans exploited the more favourable of those
> >habitats they were even more common in the past. Loo at the
> >paleogeography of Miocene apes and their proximity to the Med/Tethys
> >coasts...
>
> I know you don't like this to be pointed out, but your claims of a
> wading-based niche aren't supported by bonobos, gorillas and orangs
> living in deep forest and sometimes wading. In the perhaps 12 million
> years since the hominin-pan LCA, the ancestors of extant apes have
> apparently been primarily living in wet forest conditions, yet none
> has diverged off to fill a wading-based niche. This would seem to
> indicate that no viable such niche existed (or could be formed).
The ancestors of extant apes have been living in wet tropical
rainforest forest conditions - but this was not sufficient to drive
*them* to bipedalism. It needed an extra shove. That was provided in E
Africa by wide swings in climate from very arid (forming gallery
forest refugias, where the water's edge/area ratio was very much
higher) to very wet (where such valleys would become flooded exposing
hominin ancestors to even more need for wading.) Get it?
> <snip>
>
> >If you can post one reply when you don't just stone wall my
> >explanations with something like 'I've asked you for x and you've
> >never given it'. If you can show one microgram of objectivity that you
> >are actually open to evidence then I'll cut the rhetoric. I'm not very
> >hopeful I'm going to be able to do that, though.
>
> Yeah, I know the pattern. I ask for evidence and you respond with
> assertions. I point out that your so-called evidence consists of
> nothing but assertions and you respond with pejorative rhetoric ;0)
Ok - so let's call it a day and just agree to disagree then. I'm tired
of going round in circles. If you have nothing more to say than (yet
again) 'you've only given assertions' - when that's all I could
possibly give and that's all any of the models have ever given - then
just don't bother.
Algis Kuliukas
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