"Darwinists would maintain that OOL( chemical evolution) has nothing to do with Darwinism ( biological evolution)"

This is a widespread view, but as the old joke says about the process of making sausage, it's best not to look at it too closely.

Theories of abiogenesis and the theory of common descent are about as intimately linked as any two theories can be, insofar as how we understand the one immediately affects how we perceive the other. Stuart Kaufmann grasps this, as do a handful of other perceptive theorists (e.g., Christian Schwabe). The splitting-off of abiogenesis from common descent is almost entirely a rhetorical move, driven by the very natural desire to isolate one theory (common descent) from the weaknesses of another (abiogenesis). But in the actual science of origins, the two theories live in the same house, wash in the same tub, and eat from the same table.

More later -- and more on the topics above in this thread, too. Off to Andrews University for a lecture (on common descent, of course).

[ 28 February 2002: Message edited by: Paul A. Nelson ]

quote:

---

“This survival-of-the-fittest scenario takes place even at the level of molecules. On primordial Earth, chemicals with slight individual variations must have replicated themselves and competed with one another, scientists believe. The successful ones gave rise to the complex biological molecules that serve living organisms today.” (Schmidt, Karen A., “Evolution in a Test Tube,” Science News, vol. 144 (August 7, 1993), p. 90)

---

Another area is in teaching children. Though another BB stream on this topic was deleted, I think this is a relevant approach because children don't have professorships to defend or grants to justify, and so can see a lot of things that we blind ourselves to out of self-defense.

quote:

---

Theories of abiogenesis and the theory of common descent are about as intimately linked as any two theories can be, insofar as how we understand the one immediately affects how we perceive the other

---

RalphW, I don't mean to pick you out of the crowd but here are some problems with your post that I'd like for you to address in subsequent posts.

"The biggest barrier that I see to any criticism of Darwinism is the visceral resistanceso many people seem to have to the possibility that the universe (or the life within it) might have the shape it does because of the work of an intelligent designer." -self explanatory (see bold)

"Another area is in teaching children. Though another BB stream on this topic was deleted, I think this is a relevant approach because children don't have professorships to defend or grants to justify, and so can see a lot of things that we blind ourselves to out of self-defense." - this is a grand stereotype, please do avoid these. Also, how is the teaching of children relevant to the scientific issues?

quote:

---

Originally posted by Paul A. Nelson:
Hi Drosera,

If you're still reading this thread, can you tell me where you got that phylogeny you posted? Thanks. I have some questions about it.

---

Hey Paul,

Talkorigins, Theobald's FAQ

(hint for the future: right-click on a graphic, go to 'properties', and you get the URL.)

It should be noted that the graphic is a greatly simplified representation showing just some of the major eukaryote branches of the tree. And it is not to scale time-wise as I previously mentioned.

Again, my point is that a precambrian rabbit would nuke this tree, whereas transitional arthropods in the Cambrian and simple (potential) bilaterans in the Precambrian are in accord with it.

It should be noted that the graphic is a greatly simplified representation showing just some of the major eukaryote branches of the tree.

But it's entirely misleading. I would never give this diagram to a student.

quote:

---

Originally posted by Paul A. Nelson:
Drosera wrote:

It should be noted that the graphic is a greatly simplified representation showing just some of the major eukaryote branches of the tree.

But it's entirely misleading. I would never give this diagram to a student.

---

How so?

quote:

---

I think you should edit your post to remove the figure. Borrowing diagrams from talk.origins FAQs is, generally speaking, a bad idea.

---

Again, what's wrong with it, and what would a proper diagram look like?

Of course, any phylogenetic tree put in a single figure is going to be incomplete. To get a sense of the complete thing (as far as it's been worked out, obviously there are areas of uncertainty, although to head off the obvious direction of this thread any discussion of uncertainty in phylogenetic tree construction must explicitly address the relative magnitude of the disagreement in question.), check out the Tree of Life web project.

It takes an awful lot of clicking to get to Homo sapiens.

For a rather detailed discussion of the statistical similarity of even "incongruent" trees, be sure to click here.

Not all disagreements are equal.

What, from the phylogeny you posted, is a student likely to infer about the presence of mitochondria in eukaryotes?

Let's start there.

quote:

---

Originally posted by Paul A. Nelson:
Drosera,

What, from the phylogeny you posted, is a student likely to infer about the presence of mitochondria in eukaryotes?

Let's start there.

Again: get rid of the figure. It's talk.origins rubbish.

---

Hmm, the temperature appears to be going up...perhaps its Friday?

Regarding mitochondria, all of the eukaryotes in the figure do indeed have mitochondria if I'm not mistaken, and my impression is that they [mitochondria, I mean] are currently thought to be primitive in known eukaryotes.

There are some eukaryotes lacking mitochondria, but as I understand it, current opinion is that they are secondarily derived as the protozoans in question have "mitochondrial genes" and things like organelles that look like mitochondria that have lost their genes completely...

Any other evidence for the "rubbish" claim?

Drosera

[ 01 March 2002: Message edited by: Drosera ]

Regarding mitochondria, all of the eukaryotes in the figure do indeed have mitochondria if I'm not mistaken, and my impression is that they [mitochondria, I mean] are currently thought to be primitive in known eukaryotes.

But all eukaryotes do not have mitochondria. That is, however, exactly the impression your diagram creates. If I gave this diagram to a student, he would be misled. Saying that absence of mitochondria is "secondarily derived" is not something one could learn from the figure. That's a theory-soaked assumption.

You asked:

Any other evidence for the "rubbish" claim?

Sure. What's your evidence that all nervous and vascular systems are homologous?

Let's get down to the nitty-gritty. Did you make this figure?

[ 01 March 2002: Message edited by: Paul A. Nelson ]

quote:

---

Originally posted by Paul A. Nelson:
Drosera wrote:

Regarding mitochondria, all of the eukaryotes in the figure do indeed have mitochondria if I'm not mistaken, and my impression is that they [mitochondria, I mean] are currently thought to be primitive in known eukaryotes.

But all eukaryotes do not have mitochondria. That is, however, exactly the impression your diagram creates. If I gave this diagram to a student, he would be misled. Saying that absence of mitochondria is "secondarily derived" is not something one could learn from the figure. That's a theory-soaked assumption.

---

Puh-lease. Not all tetrapods have four legs, either, but we still use the word.

Regarding mitochondria, in fact a lot of biologists until recently thought that they *weren't* primitive in extant eukaryotes, because various protozoans lacked them. But, in fact, recent direct evidence (genomes and structural studies) has indicated that the ancestors of these protozans in fact had mitochondria. I don't see the theory-ladenness.

A similar case is that some amphibians lack legs (and hence, digits). Is it really "theory-laden" to suggest that their ancestors had them but lost them (particularly as losing features is a particular easy thing to do in evolution)?

quote:

---

You asked:

Any other evidence for the "rubbish" claim?

Sure. What's your evidence that all nervous and vascular systems are homologous?

---

Well, 5 seconds on google got me this:

Chordates and Arthropod Body Plans: The Neural Tube Perspective

...looks like a number of genes involved with the neural system are related (whatever you think about the inversion theory, the page gives some pros and cons).

quote:

---

Let's get down to the nitty-gritty. Did you make this figure?

---

I wish. I have nothing like Dr. Theobald's expertise in these mattes, I just happened upon his (long) article!

Why would it matter, anyway?

Drosera

[ 01 March 2002: Message edited by: Drosera ]

Why would it matter, anyway?

Because it's easier to ask the author to support his own work, than someone who borrowed the diagram from elsewhere.

The phylogeny implies that the sister group of "prokaryotes" (a negatively-defined taxon) is "eukaryotes," and that all eukaryotes have mitochondria. This is false. No node in the diagram indicates the loss of mitochondria. This phylogeny wouldn't pass muster in an undergraduate systematics class.

The phylogeny states that all vascular and nervous systems are homologous. Since you aren't the author of the figure, Drosera, could you kindly give the evidence that Douglas Theobald used to place that node? I assume he did not use the article you found in the Google search.

[ 01 March 2002: Message edited by: Paul A. Nelson ]

quote:

---

Originally posted by Paul A. Nelson:
The phylogeny implies that the sister group of "prokaryotes" (a negatively-defined taxon) is "eukaryotes," and that all eukaryotes have mitochondria. This is false. No node in the diagram indicates the loss of mitochondria. This phylogeny wouldn't pass muster in an undergraduate systematics class.

---

None of the eukaryotes in the diagram *have* lost mitochondria. There are a lot of branches left out of this tree.

Your objection is just as weak as the objection that the "digits" node for amphibians is misleading because some amphibians have lost their legs! Some degree of proportionality, please!

quote:

---

The phylogeny states that all vascular and nervous systems are homologous. Since you aren't the author of the figure, Drosera, could you kindly give the evidence that Douglas Theobald used to place that node? I assume he did not use the article you found in the Google search.

---

Of course, the point of the figure & article was not to document, against all comers, that these systems were homologous. It was to point out a consistent and long-supported basic phylogenetic tree. I have cited evidence that the systems are in fact homologous (there are refs on that webpage to get started), so that point is accurate as well. Regarding references, I'd say that it's common knowledge, at least among biologists.

You haven't demonstrated that either the phylogeny (the main point) or the nodes (a subsidiary point) are inaccurate, despite several tries.

Pretty good for "talkorigins rubbish".

Drosera

[ 01 March 2002: Message edited by: Drosera ]