Vanderzyden

The earth's gravitational force is an acceleration acting toward the center of the earth. It points "toward the ground", and is still in effect in closed systems. Near the planet's surface, it reaches a strong value of 9.8 [meters per second, per second].

Yes, gravity acts downward whether the fetus is horizontal or vertical. Its effects are significant when the fetus is vertical, in the cephalis (head-down) presentation or upright. The design of the system must take into account the "off-horizontal" orientations, where gravity will build hydrostatic pressure in the "lower regions".

Here's another illustration that may help: Imagine a small ball bearing held in suspension at the top of a fluid-filled transparent cylinder, which is submersed in a pool of water. Now, imagine that the ball bearing is released.

1. Won't the ball bearing drop to the bottom of the cylinder?

2. At all orientations except perfectly horizontal, won't the ball bearing roll to the end which is lowest?

The answer to each, of course, is yes. Furthermore, the fluid in the low end wil be at a higher pressure than the lower end (which will equal the pressure of the pool water just outside the lower end). This should be a clear demonstration that gravity, when present, is at work in fully-immersed, fluid-filled closed systems.

John

RufusAtticus

Again, how much biological literature did you have to read to come to this conclusion? Or is this simply an arm-chair complaint?

BTW, there is no utter lack of transitionals. Find me a modern scientific paper that claims otherwise.

Well you obviously don't bother to address them. Thus you must concede that they are valid.

This sentance is not grammatically correct, thus I can't parse what you are trying to say. Please try again.

How are developmental defects comparable to falure to have proper maintance done? Before you answer, I suggest that you learn about <a href="http://www.devbio.com" target="_blank">Developmental Biology</a>. Failure to do so has doomed your entire argument so far.

~~RvFvS~~

RufusAtticus

Vander,

Please show us your equations for the affect of gravity on fetal blood pressure. I do not see how you can contine with your argument with out them. Thanx.

Albion

Are you sure you're an old-Earth creationist? Sometimes you sound just like a YEC.

Jack the Bodiless

Of course it will NOT.

The downward force of gravity in this scenario is precisely matched by the UPWARD force of the water pressure acting on the lower body, which is "squeezing the blood out".
Because the STEEL ball-bearing is DENSER than the fluid. An air-filled plastic ball will do exactly the opposite, moving UP the cylinder. And a neutrally-buoyant ball will go nowhere.
Yes, gravity is at work. But it is precisely negated by the upward thrust of buoyancy at every point in the system.
By "outer space", are you referring to the space between galaxies? There is no "gravity-free environment" available to us. The downward pull of gravity in low Earth orbit (e.g. on an orbiting space shuttle or the ISS) is almost as intense as at the Earth's surface. Everything is constantly "falling" in orbit. But the effect of gravity within a system in a weightless environment can be disregarded, just as it can in a neutrally-buoyant system.
Refuted. This is simply not true.
Childish anthropomorphism. Lightning bolts are hurled by Zeus, right? Hurled missiles require a hurler...
There are thousands of transitional forms throughout the fossil record. And the perfect correlation of homology to the evolutionary "tree of life" of common descent in the fossil record, AND the pattern of genetic similarities revealed by DNA analysis, IS knock-down evidence of universal common descent: in fact, it's as close to absolute proof as science ever gets.

You are spouting pure creationist propaganda, Vanderzyden. There is no factual basis to your claims. They are pure fiction.

Jack the Bodiless

...Incidentally, Vanderzyden, I'm curious to know why you think that ships float? Especially steel ones?

According to Vanderphysics, they'd sink like ball-bearings, right?

Or will your answer be "ships have never been proven to exist. If you believe ships exist, then please provide a report to that effect from a reputable source, with full supporting references"?

scigirl

Please explain to me how it is the fault of a fetus that he/she has a tail or other embryological defect.

Vanderzyden, if you want to claim that these defects are NOT a result of evolution, than you must do the following:

1) Prove they have nothing to do with genetics

Or

2) Prove that the genes involved in creating "human tails," aortic arches, etc, are fundamentally distinct from those same genes that produce such structures in other animals.

In addition, you must do the following:

3) Simultaneously explain why animals (which are incapable of sinning or doing "wrong things") have these exact same defects.

And what on earth do you mean by intra-species ancestral? That sounds like evolution talk to me...

scigirl

[ November 06, 2002: Message edited by: scigirl ]</p>

scigirl

Jack,

Thank you for that physics primer - I really want to believe that Vanderzyden knows what he's talking about since he says that's his field - but I find it extremely hard to believe that my animal physiology text is just blatantly wrong on a key issue in circulation.

And I still don't see the whole point of Vander's argument - how does gravity specifically relate to the placement of vessels in the fetal circulation, when the following points are clear to me:

1) Gravity acts on different axes throughout development, and throughout the day, of the fetus
2) Giraffes (after they are born) have compensated for an enormous gravity problem, but not by changing the placement of any vessel, so how could vessel placement matter that much in a tiny human fetus?

Once again I ask you vanderzyden - how does your gravity argument (which appears to be wrong anyway) even relate to the topic at hand - sub-obtimal design of the fetal circulatory system? Addressing the two points above would go a long way to help your case.

scigirl

lpetrich

Looking in PubMed for "aortic arches"; there are some cases of double ones, where one of the systemic arches does not disappear.

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=118204 09&dopt=Abstract" target="_blank">In a dog</a>.
<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=104211 02&dopt=Abstract" target="_blank">In a cat</a>.
<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=112630 02&dopt=Abstract" target="_blank">And some human cases</a>.

Searching for "double aortic arches" revealed several articles, some on undiagnosed cases of this interesting aberration.

In many of these cases, the extra arch squeezes the esophagus and/or the trachea, interfering with swallowing and breathing. As a result, that arch's effects <a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=118449 71&dopt=Abstract" target="_blank">had once been misdiagnosed as asthma</a>.

I wonder what Vanderzyden thinks about that extra systemic arch persisting.

[ November 06, 2002: Message edited by: lpetrich ]</p>

pz

Let's be even more specific. Perhaps Vanderzyden can explain to us:

1. What mechanism generates the extra arch,

2. whether it is an improvement, an error, or a 'corruption" of the circulatory system, and

3. since he favors teleological explanations, I'd like to know why these individuals have this odd trait.