Re: Bipedalism in different substrates

From: Paul Crowley (slkwuoiutiuytciuyik_at_slkjlskjoioue.com)
Date: 08/23/04 

Date: Mon, 23 Aug 2004 17:51:45 +0100

"NA Sides" <nas@sonic.net> wrote in message news:o47ci0h197upcsf63et5gb304ns69k77e2@4ax.com...

> On Thu, 19 Aug 2004 18:35:10 +0100, "Paul Crowley"

> >> The point is that infants
> >> can be, and are, carried dorsally. If proto-hominins employed a dual
> >> locomotory strategy, that's how they *would* be carried during the
> >> periods when females were knucklewalking.
> >
> >Then it's a nutty theory. One of the
> >principal virtues of knucklewalking is that
> >it enables the animal to make good (and
> >often fast) progress through ordinary
> >woodland and low brush, full of branches
> >and other obstacles at a height of two feet
> >or so. Infants cannot ride ventrally when
> >their mothers are on such ground.

That was a typo -- as you probably realised
(or should have realised). I meant to write:
"Infants cannot ride DORSALLY when their
mothers are on such ground." The branches,
etc., would brush them off their mothers'
backs before she had moved a few feet.
But there is no impediment to the infant
being carried ventrally on such ground.

> I've been through this whole discussion already with Algis. Human
> beings can hike for long distances through such territory.

Nonsense. Of course they can't. Humans
can only travel through such territory by
cutting paths with pangas or machetes as
they go along -- a desperately slow, and
usually hopelessly uneconomic method.

> Hunter-gathereres traveled farther in a day's foraging than do any
> extant great ape and occupied a far wider range of habitats. This
> ability to range widely is one of the most distinguishing features of
> our own species and would have been shared to a considerable extent
> even by our early hominin ancestors. Knucklewalking appears less well
> suited to long distance foraging. It may (or perhaps may not) have
> provided an advantage over early hominins for short distance bursts of
> speed. I'm assuming it did provide that advantage. As for your
> statement that infants couldn't have ridden ventrally when their
> mothers carry them over rough and bushy terrain, you're agreeing with
> what I said. If proto-hominins employed a dual locomotory strategy,
> mothers would either have walked bipedally over such terrain or would
> have carried infants on their backs when they were knucklewalking.

All the above is either irrelevant or nonsense
or both. How would 'dual-function' mothers
carry their infants when travelling? You say
that they would walk bipedally -- presumably
carrying the infants in their arms. But that is
a FAR less effective system than the
quadrupedal one, where the infant hangs on
underneath. The mother has her hands free at
all times and can go through low bush, forage,
fight, climb, or react instantly to whatever
might happen. If the mother-infant dyad is
capable of standard quadrupedal motion, there
is no reason why they would switch to bipedal
locomotion --and many reasons why they
would not.

You will NEVER see a mother-infant dyad in
modern apes moving bipedally -- except in
highly peculiar circumstances and for very
short distances. That very obvious fact is
ignored by all standard PA types (and by the
likes of Algis) since the model (or all hominids
and hominoids) that fully occupies their
brains is exclusively male.

> <snip>
>
> >> >> Speciations, or in some instances ecologically mediated morphological
> >> >> differentiation that may not constitute complete speciation, have
> >> >> occurred on single islands.
> >> >
> >> >Such as?
> >>
> >> I've told you already. I also discussed it with you in that same
> >> thread a year ago. Go to Google Groups and read it.
> >
> >If these remarkable single islands existed
> >outside your imagination there might be
> >a chance that you would know their names.
>
> The lemurs of Madagascar represent a unique set of related species
> that apparently have diverged on that island, in a process of adaptive
> radiation, from a common ancestral stock.

Or, more likely, they represent a set of
primates which at one time ranged over
the whole of Africa -- so that Madagascar
is, to some extent, a living museum. In any
case, Madagascar is much larger than the
kinds of islands we were discussing.

> The honeycreepers of Hawaii
> are another case exhibiting clear ecological specialization and
> population segregation according to diet and habitat preference.

I know nothing about these species -- but
(a) they moved into new unexploited habitats
with almost zero competition; and (b) even
if what you say is true, it has no relevance
to the creation of new niches on continents
for large, highly mobile hominoids.

> The
> various species and subspecies of Galapagos finches apparently also
> arose through adaptive radiation within that archipelago. Birds
> originating on one island obviously have in some cases migrated or
> been blown by storms between one island and another and this has
> contributed to the variety of species within some archipelagos. But
> this kind of geographic isolation is just one factor,

It is more than 'just one factor'. It is the
overwhelmingly dominating one, that
makes your use of such species as
'examples' hopeless, and absurd beyond
words.

> and such
> migration is much more likely in birds than mammals. Habitat
> preference and differentiated foraging strategies, mate preference,
> and other ecological and behavioral factors also can contribute to
> speciation and the maintenance of population differences even among
> contiguous populations.

As I keep saying, there is little problem
about the maintenance; but there is a
major one about the speciation. Putting
them together in the same sentence -- as
though they were much the same thing
-- only demonstrates your complete lack
of understanding of the issues.

> >> >> >'Maintenance' is rarely a problem. The
> >> >> >two species cease to be inter-fertile --
> >> >> >in a variety of ways. It's the initial
> >> >> >speciation that is the problem.
> >> >>
> >> >> This appears not to be the case.
> >> >
> >> >From WHAT evidence or data?
> >>
> >> From the Grants' Galapagos study.
> >
> >The study by the Grants extended over a
> >few decades. No one except you claims
> >that it has any bearing on how populations
> >speciate in the first place.
>
> You asked "WHAT evidence or data?" and I gave you a reference to the
> longest lasting and most complete field study ever done of what are
> apparently contiguous subspecies maintaining their individual
> identities over time despite having at least some ability to
> interbreed. I can give you references to other papers detailing
> studies showing similar results.

As I keep saying, there is little problem
about the maintenance; but there is a
major one about the speciation.

> It appears that many species lack full genetic or morphological
> isolating mechanisms that would separate them off absolutely from
> other closely related species. Wolves and coyotes, for example, are
> apparently fully interfertile. Red wolves and coyotes formerly kept
> separate in the American Southeast, but with the near extinction of
> wolves in large areas of their former habitat, some red wolves
> apparently bred with gray wolves and sometimes also with coyotes. One
> of the main barriers to gene flow between contiguous populations
> apparently had been size differences and mate preference, and when the
> situation changed with more individuals having difficulty obtaining
> (same species) mating partners, hybridization increased.

What relevance does any of that have
to speciations within hominoids?

> >> Dietary differences correlated with the morphological differences. If
> >> you know of other field research that conflicts with their
> >> observations, what are they?
> >
> >We'd need 'field research' extending over
> >several centuries, at a minimum. So don't
> >expect to find many studies.
>
> You're really a character, Paul. In our previous discussion about
> human salt requirements you were willing to accept the claims of a
> paper put out by the Salt Institute (a lobbying organization for the
> salt industry) over the overwhelming consensus of medical researchers.

The "overwhelming consensus of medical
researchers" tells us only that they have a
sheep-like mentality -- but we already knew
that. It's not so long since the "overwhelming
consensus of medical researchers" would
have heard nothing against blood-letting.
All that matters in the salt issue, or in the
speciation issue -- or any issue -- is the
evidence; and, as ever, you can't find any.
Like those medics, you prefer to rely on
what you see as 'overwhelming consensus'
(i.e. ancient prejudice) and forget the need
for evidence.

> Now here you are ready to dismiss, because it hasn't extended for
> "several centuries, at a minimum," the longest continued and most
> rigorously done study of evolution in action.

How long would it take for a new mammalian
species to emerge? How long would it take
for a new hominoid species to become
established? How could it happen? Anyone
who expects some observations of bird
populations over a few decades to yield
relevant answers is a fool.

> Sorry about your emotional distress. Let me clarify the statements
> that disturbed you. I don't deny that some form of geographical
> isolation is usually required to bring about speciation,

When did you last see that mentioned in
any discussion of the hominid speciation
in a learned journal? What is _thought_
to have been the minimum period? How
is it _thought_ to have been achieved?
(I emphasise 'thought' because you know
as well as me that there is none.)

> Our own ancestors, the Miocene apes that gave rise to hominins, would
> have been, to some extent at least, behaviorally flexible ecological
> generalists like the Cocos finches, but they weren't restricted to a
> single small island.

How do you know?

> Due to long-term aridification, the
> continent-wide rain-forest was thinning in some regions and breaking
> up into patchy forest, woodland, wooded-grassland and more open
> grassland mosaics.

Yawn. This mythical 'drying period' serves
modern PA people in much the same manner
as the 'fluvian period' (i.e. the Great Biblical
Flood) served Victorians. It can explain
everything and can be hypothesised for any
time that happens to be convenient, and
extend over any period that is desired. It can
be theorised to recur as often as the theory-
maker requires. It's not unlike Marc's (and
Algis's?) periods of immersion into water --
a general-purpose 'solution' to all problems.

> Some apes, those that inhabited areas that retained
> their ancient rain-forest character, would have retained more of the
> ancestral characteristics. Our hominin ancestors would have descended
> from populations in different areas that were undergoing more habitat
> change.

Ridiculous. There has been plenty of
'habitat change' in the last 15 Kyr. How
many species benefited from it all?
How many new species emerged?
Can you show any parallels between
your hypothesised ancient period of
'habitat change' and THIS very-well-
understood one? Any parallels at all?
No matter how remote? No? Presumably
the idea that you ought to be able to do
so, has never occurred to you.

> Perhaps there would at first have been some degree of gene
> flow between populations living in deep forest and more open areas,
> but this would have declined as different groups took up different
> "trades" suited to the habitats they occupied and incorporating
> somewhat disparate foraging strategies.

What creates the geographical separation?
What prevents the gene flow? Why
didn't the 'chimps' continue to occupy the
more open forest?

> We know now that even chimps
> have culture and proto-hominins would have passed skills from one
> generation to the next as cultural traditions. This in itself could
> function as a behavioral isolating mechanism.

So why is there no evidence that such a
divergence has never happened to chimps?
And what does all this have to do with
bipedalism? Obviously nothing. That's
not really a problem, so we can forget it --
right? That's always the best way of treating
problems. Just forget them. Pretend that
they don't exist, and pray that they'll go
away.

Paul.

Relevant Pages

  • Re: Ancestor Survives
    ... You have to determine which species is reproductively isolated from the ancestor. ... Your approach appears to be that when a speciation event occurs, we have to assume that two new species are created, because we don't know which can lay claim to being the ancestral species. ... cases speciation appears to occur after initial divergent selection in a population is followed by an event that isolates the populations. ...
    (talk.origins)
  • Re: Ancestor Survives
    ... You have to determine which species is reproductively isolated from the ancestor. ... Your approach appears to be that when a speciation event occurs, we have to assume that two new species are created, because we don't know which can lay claim to being the ancestral species. ... cases speciation appears to occur after initial divergent selection in a population is followed by an event that isolates the populations. ...
    (talk.origins)
  • Re: Ancestor Survives
    ... You have to determine which species is reproductively isolated from the ancestor. ... Your approach appears to be that when a speciation event occurs, we have to assume that two new species are created, because we don't know which can lay claim to being the ancestral species. ... So the same pop-gen arguments that apply to populations diverse in space should also apply to populations diverse in time. ...
    (talk.origins)
  • Re: Ancestor Survives
    ... You have to determine which species is reproductively isolated from the ancestor. ... Your approach appears to be that when a speciation event occurs, we have to assume that two new species are created, because we don't know which can lay claim to being the ancestral species. ... So the same pop-gen arguments that apply to populations diverse in space should also apply to populations diverse in time. ...
    (talk.origins)
  • Re: Defining&testing "macroevolution" (was: Testing the Laws of Intelligence)
    ... evolution of populations below the level of speciation. ... It means that changes within a population or within one species is ... called "microevolution", as opposed to the origin of new species and ... Bacteria don't reproduce sexually, ...
    (talk.origins)