Re: A *Dry* Discussion About The Origin Of Bipedalism

"mclark" <biteme@xxxxxxxxxxx> wrote in message
news:enCQe.36627$32.18943@xxxxxxxxxxxxxxxxxxxxxxxx

> >> Well, if you ask me, I think this whole 90% twist from
> >> horizontal to vertical is a response to the problem of moving
> >> an increasingly large body through the branches of trees.
> >> I think I had this conversation with Pauline a while back
> >> and if I recall (without a search), I think that I said something
> >> about the nature of trees (they have a vertical trunk, in most
> >> cases, branches angle off from this trunk at increasing angles
> >> as they move away from the trunk and that useful resources
> >> are usually found toward the termination of these branches),
> >> and that larger bodies would be restricted by certain physical
> >> laws from employing the normal monkey modes of travel.

This is another wonderful example of Mikey
trying to think. On the one hand, you want to
cheer, and yell encouragement; on the other,
you have to cringe with embarrassment and
grimace with pain. It's somewhere between
seeing a one-year-old taking his first steps
and your mother (who's enormously fat) being
on stage trying to sing, when she hasn't a note
of music in any bone.

> >> Add this to the fact that running
> >> along the tops of branches is actually *more* stable that walking,
> >> and the observation that *sitting* adds its own set of variables
> >> to the mix (changes to the lower spine) and you have a certain
> >> inevitability to the notion that those apes thus pre-adapted to
> >> bipedalism would find themselves moving bipedally when
> >> ~whatever~ moved them to the ground.

First, try to remember that the species does
not consist only of adult males -- but of
mothers carrying infants up there, and
attending to other small children. (OK,
you may _really_ believe that the species
consisted only of adult males -- so treat this
as a kind of exercise, or just a good mental
discipline.)

> "rmacfarl" <rmacfarl@xxxxxxxxxxxxxxxx> wrote in message
> news:1125301280.342279.221630@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

> > What I've seen of chimps suggest a similar approach. I have a mental
> > image of males hunting by climbing outward on all fours toward a
> > trapped monkey, for example.

Chimps RUN along such branches -- they
move really fast when they are catching
monkeys.

> Which was my point, of course. Those 3 or 4 points of contact
> are not necessarily the same branch.

For chimps, chasing monkeys, they often
are (indeed, that is usually the case).

> I know the difficulty. The problem, as I see it, is how you
> get an otherwise four-footed primate to stand up whilst
> engaged in the normal, everyday activities of a quadruped.

All you have to do is to see them placed in
an environment where there are NO suitable
trees. Of course, that means no dangerous
predators, forcing them to stay in trees. But
there are plenty of such situations: Present-
day Borneo or Madagascar, for example --
assuming that there were no humans in such
places.

> It *may* be that these adjustments are the result of increasing
> body size --which may be a reaction to something else (like
> scarce resources or sexual politics).

Nope. That dilemma is faced by our cousins --
in every generation. There are only two real
answers -- stay small enough to sleep in trees
(chimps), or let the males get so huge that they
can stay on the ground able to fight off
predators (gorillas).

> Increasing body size then
> introduces all these other difficulties --how to move efficiently
> in an environment with shrinking possibilities. If you're restricted
> to the larger branches, you would be restricted in your adaptive
> responses. Once you have a *climbing* orthograde ape,
> moving it to the ground becomes a natural progression. Figuring
> out what drove this move is another difficulty hinted at previously.
> Were they pushed, pulled, what?

'Pushing' is evolutionary nonsense. So is
'pulling' (in nearly all scenarios). Just put
them in an environment where they do not
face the pressures that keep chimps and
female gorillas sleeping in trees on nearly
every night of their lives.

> Did they leave because the
> trees dropped out from under them or were they drawn away
> by the promise of more lucrative jobs in the city? I think that it
> is pretty well established that at some point our ancestors were
> *living* in trees. We now live on the ground.

Avoid the word 'live'. It's too vague.
Use 'sleep'. Then you might be able to
focus on the problem.


Paul.



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