Re: Bipedalism in different substrates

From: Charles (lmno_at_mindspring.com)
Date: 07/14/04 

Date: Wed, 14 Jul 2004 05:00:03 GMT

"Jason Eshleman" <jae@ucdavis.edu> wrote in message
news:b7af43cb.0407131753.5db548d8@posting.google.com...
> NA Sides <nas@sonic.net> wrote in message
news:<ovv7f0dl59q6022pj72q659g4j2ep5gc3u@4ax.com>...
> > On 13 Jul 2004 01:04:51 -0700, algis@RiverApes.com (Algis Kuliukas)
> > wrote:
> >
> > [I don't know if Jason has de-plonked you, Algis, so I'm posting this
> > so that he will see it. BTW, are you going to reply to my July 11
> > post? It pointed out a number of weaknesses and inconsistencies in
> > your claims that you need to address.]
>
> Don't expect him to actually address what you've asked with anything
> more than assertion wrapped with "could haves" and "mights," Norm. If
> it happens now, it will be a first time.
>
> Honestly, it's more like rubber-necking at an accident when I read
> what he's posting. In three years I've not seen evidence that he
> learns anything, but rather still fishes for tidbits to support his
> preconceived notions.

HTe more I hear about it, the more it appears that you may be Panglossian,
per this website:
http://www.aaas.org/spp/dser/evolution/history/spandrel.shtml
"...you acknowledge the rival but circumscribe its domain of action so
narrowly that it cannot have any importance in the affairs of nature. Then,
you often congratulate yourself for being such an undogmatic and ecumenical
chap. We maintain that alternatives to selection for best overall design
have generally been relegated to unimportance by this mode of argument."
This despite your excellent recent posts concerning selection.

 I'm still letting others decide if he's written
> something worth responding to. What you've forwarded here isn't
> making me rethink my decision. But if others want to make points or
> have questions, I'm not shying from them. I'm simply tired of seeing
> nothing but assertion driven by some religious conviction that wading
> MUST be the answer. Frankly, I don't care if it is or isn't, but I do
> care that he's radically abusing science in the process and since it
> doesn't look like anything will make him change his mind, point by
> point there's no reason to engage him other than pure amusement.
>
> My scan through makes it look like the sum total of his rebuttal is
> stead-fast insistence that he's still right, wrapped in a rather
> amateurish interpretation of selection. There's so many holes in what
> he's put together and he really doesn't see it and he's stubbornly
> resistant to the criticism. He's started with the conclusion:

What I read are merely hypotheses. Algis gives these three observations:
"a) swimming is riskier than not swimming.
b) wading bipedally allows you to not swim where you might otherwise
have to swim.
c) the fact that we swim better than apes implies that our ancestors
moved through water more than their's did."
which are indeed scientifically testable. or at least are logically
consistent. Given that, I am not myself convinced that wading will turn out
to be THE answer, but at least Algis is thinking through this stuff, and it
is good to have your input. And like Algis, I would like to hear your
critiques of the other theories about the origins of bipedalism.... unless
that is a trait that cannot be separated from the whole organism and
independently tested....

>water
> was responsible, and as a consequence, he doens't ask any real
> questions. But we can play a game of 20 questions. He should consider
> all of the following:
>
> 1. Did our ancestors wade regularly? [A "may have/could have" is not
> a sufficient answer nor is "it's obvious."] How do we know this or how
> could we know this?
> 2. While the environment may have made it possible, how do we know
> that this environmental association isn't a taphonomic bias?
> 3. Are there other, clearly "unaquatic" creatures that similarly
> inhabit these same deposits?
> 4. As extant apes get in the water with great reluctance, what would
> compel a protohominid to wade?

fire in the trees?
childbirth?
heat? (for the latter, last week's Science News has an excellent article
about heat deaths and pollution.... and points out that more people die from
heat than any other natural phenomena such as tornadoes or lightning.)

> 5. What resources are available to the waders that aren't available to
> an animal that wasn't wading?
> 6. Is there any evidence that hominids utilized these resources to any
> appreciable degree? [A "may have/could have" is not a sufficient
> answer nor is "it's obvious."]

Well, yes. Part of the current human diet includes raw seafood, that is,
sushi. Apparently, no current cultures eat raw bone marrow.

> 7. Are these resources sufficient to dictate that a "wading ape"
> niche, where an ape spent and appreciable period of its time moving
> about in the water could exist?

I haven't a clue. But I can say that waterfront property is more expensive
than waterless property, implying that humans value that more for some
unspecified stupid reason. My opinion, if you are interested though I
suspect you aren't, is that we did indeed evolve in a "mosaic" and a large
portion of that mosaic was beside rivers, lakes and the sea.

> 8. It's not sufficient to just say they're there. Resources cost
> something to get. Since moving through water is energetically costly,
> what's the real return on investment in trying to acquire these items?
> 9. Given that extant primates can (and do) wade without any
> morphological specializations, why would it follow that hominids would
> have undergone some selective change to a wading environment?

I asked a similar question earlier in this same thread... why, if bonobos
are so good at bipedal rope walking... aren't they the obligate bipedal
creature? we did not develop the ability while still arboreal.
later,
charles

> 10. What particular selective changes would wading favor and why?
> 11. Why haven't any other waders or aquatic foragers undergone the
> changes that the "wading hypothesis" says wading caused in our
> lineage?
> 13. If the selective pressure isn't sufficient to alter the lower
> extremities in deeper water, do forces exist in shallower water that
> seem to favor the suite of characteristics we share with the earliest
> well-described hominids? [A "may have/could have" is not a sufficient
> answer nor is "it's obvious."]
> 14. Given that extant apes have been reported to wade quadrupedally,
> what would be the incentive for an ape to move bipedally through
> shallow water?
> 15. What's the energetic demand at different depths?
> 16. If the selective force is relative efficiency why, given that
> selection for efficiency requires both a differential in efficiency in
> the particular environment and sufficient exposure to this
> differential process, would any given wading ape spend enough time in
> the particular selective environment to present sufficient exposure to
> selective differences? [I realize that he's not going to deal with
> this one head on because he's going to say that *any* difference is
> signficant. On this there's no polite way to put it. He's simply
> wrong.]
> 17. Does this involve trips back and forth in and out of the water
> (and if so why would they do this given the high energy costs
> associated with walking through water) or movement parallel to shore
> in relatively shallow water (and if so why would they do this given
> the high energy costs associated with walking through water) and do
> any other creatures practice this type of behavior?
> 18. Is there actually an appreciable difference in the efficiency of
> bipedal wading between an ape and a bipedal hominid? [A "may
> have/could have" is not a sufficient answer nor is "it's obvious."]
> 19. Do any other organisms who wade regularly (eg many bears, some
> monkeys) who are capable of facultative bipedalism show any
> morphological changes associated with making their wading stride more
> efficient?
> 20. Given that we *do* see other aquatic foragers, how are we
> similar or dissimilar?
>
> And no, there's not a model that's stood up to ALL of scrutiny.
> Nothing's out there currently that would withstand that sort of
> scrutiny and that's why there's not an "orthodoxy." That's why
> there's not a consensus. What he doesn't seem to get is that his
> model is failing in so many ways, relying on a ridiculous degree of
> unsubstantiated speculation.

Quantcast