Charles Darwin

Neat! Thanks.

Charles Darwin

Because there is a world of difference between one gull adapting into an allied species and a fish becoming a giraffe. The macroevolution we observe is misnamed, because we associate macroevolution with the vast amounts of change required by evolution.


How did that get in there? I was not making any such argument for intelligent design.

lpetrich

"Charles Darwin" has a LOT to learn about comparative anatomy, because numbers of vertebrae can vary rather drastically. Furthermore, he ought not to whine that he's too busy when he's challenged on anything, because he does not seem too busy to make his claims.

Frogs have at most 13 vertebrae and usually less.

Snakes have typically 100 to 400 vertebrae, with individuals of a species often having varying numbers of them.

One very interesting recent result is that front-to-rear identity is specified by Hox genes over much of the animal kingdom; what patterns a fly also patterns a frog.

This is from a paper comparing chicken and mouse Hox-gene expression; I've added the human vertebrae for comparison purposes; notice that we are much more like mice than like chickens in this respect.

Somites are body segments; vertebrae are always between somites.

First cervical (neck) somite
Human: 5 (assumed)
Mouse: 5
Chicken: 5

FIrst thoracic (chest) somite
Human: 12
Mouse: 12
Chicken: 19
Hox before: c5
Hox after: c6

First lumbar (belly) somite
Human: 24
Mouse: 25
Chicken: 26
Hox before: a9, c9

First sacral (hip) somite
Human: 29
Mouse: 31
Chicken: 30
Hox before: d9
Hox after: d10

First caudal (tail) somite
Human: 34
Mouse: 35
Chicken: 39
Hox before: d11
Hox after: d12

Interestingly, front limbs appear between the Hoxc6 and Hoxc8 front boundaries. But snakes have their Hoxc8 front boundary moved up to their Hoxc6 one, which keeps their front limbs from forming; they have no Hoxc6-without-Hoxc8 region for those limbs to form in.

I've clipped the mouse-chicken diagram out of one of the references and included it with this message; I hope that this is not a serious copyright violation.

Sources:

Developmental basis of limblessness and axial patterning in snakes

Page 17 of these dev-bio class lecture notes

These class notes on Hox genes.

Charles Darwin

quote:
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Originally posted by Charles Darwin
I'm afraid there is religion involved here. But first, you nor anyone else has ever built a living cell, much less human being. So arguments about the coccyx, appendix, or whatever else, not being designed quite right ring hollow.
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I'm afraid that whistling sound was on your end, not mine. You are the one who missed the point; or should I say, contrived one out of thin air. You see, I never made the point about echolocation, or whatever else, being really well designed. My point was that your idea about echolocation arising spontaneously (and that claim being a fact!) is simply bizarre.

lpetrich

Charles Darwin:
Actually, homology has NOT held up rather well. It is now evident that one cannot know whether something is a homology or an analogy.

One can do this with considerable success with gene sequences, and one can also do this with cladistics. In fact, with cladistics, one can get an estimate of the minimum amount of convergent evolution that was present. And it is often much less than one would get for a non-evolution-like distribution of features.

And since evolutionists now have given up requiring the tracing of homologies through development paths and common genes; we are in a situation where anything goes.

CD shows a total lack of familiarity with the evolutionary-biology literature; homology is alive and well.

One example that De Beer gives is the development of the eye lens in two allied frog species. In one the optic cup induces the differentiation of adjacent tissue to form the lense. In the other species, the differentiation is not induced by the optic cup.

I wonder what's been done since then on that subject -- a lot can happen in 30 years.

The example is not unusual. There are many similarities that do not come from similar development pathways or genes.

???

(on Pax6, which induces eye formation...)
But with evolution, we must assume that this sophisticated master-control gene predates advanced organs. It had to have been present in the primitive common ancestor of all these species. Amazing.

Why not? It helps start the growth of an eye; what happens afterwards depends on other genes. Thus, mouse Pax6 transplanted into a fruit-fly embryo will induce the growth of fly eyes but not mouse eyes.

And a common ancestor with eyes is not as implausible as it might seem -- especially if its eyes had been simple eyespots.

So Pax6 is another case of deep homology in the animal kingdom.

An even flimsier explanation would be to say that PAX6 was recruited as a vision master-control gene many times over. The homology becomes an analogy!

A totally superfluous hypothesis.

lpetrich

"Charles Darwin":
(on fancy bat echolocation...)
Now let's just be frank. You don't have the details. In fact, you don't have the foggiest idea whether such a thing could really evolve. ...

And are you willing to be equally skeptical about your pet hypothesis that the ancestors of bats were poofed into existence? Are you willing to demand the same level of detail that you demand for an evolution-based scenario?

To get anywhere close to the understanding that CD demands will require understanding how bat-echolocation systems are produced from their genes, and that has not been the biggest priority of evolutionary developmental biologists. Maybe as biotechnology improves we will see a change.

lpetrich

"Charles Darwin":
See this is the problem. Everything is taken for granted, though you have no details. It is just so easy; meanwhile, there is no science here, just speculation.

Like your pet hypothesis of poofing into existence?

... Your receiver has to be protected during the shout so it isn't ringing when it comes time to listen. This is PART of the the echolocation system.

ONLY if one wants to build a very sensitive system; a low-sensitivity system does not need that elaboration.

And you say there are easy ways to handle rejection of other bat's chirps.

I'm sure that CD can distinguish his voice from other people's voices. And if we can do that, then bats may also be able to do that.

lpetrich

And what will do the job? Short of exploring the entire history of life on Earth in a time machine, of course.

And why are you letting creationism off easy as compared to evolution? SERIOUSLY.

Why aren't you demanding that creationists work out the mechanism of the poofs that new species appear in? And why some features were selected and not others for the organisms poofed into existence?

lpetrich

Charles Darwin:
They also don't come running over the hill just in the nick of time.

Horses only do that if they have cavalry soldiers riding them.

Oh, that's right. land animals evolved before flying animals -- creationism must be wrong.

So you now accept evolution?

Jack the Bodiless

...So you're now arguing that "evolutionists" must be lying when they claim that blind cave fish really are blind?

This seems like a testable claim. Will you abandon creationism if you find that those fish really ARE blind?

If not: why not?

...And what do YOU call ostrich "wings"?
We've already seen that your usage of "ludicrous" is (to put it politely) somewhat unusual.

The "POOF! ... POOF! ... POOF!" theory is not ludicrous?