Hi Joshua - The comments in brackets [like this] are yours and are not in the original, correct?
No, it’s a modification of the body plan we share with whales. The nostrils on embryonic whales are in the same position as ours.
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Correct. Look at the links for yourself.
I think that body plans are at or near the heart of the Gould vs. Conway Morris debate about evolution’s predictability. Gould interpreted the Precambrian fossil record as depicting a plethora of body plans lost forever. Conway Morris (the world’s expert on the topic) sees them very differently, essentially as modifications of existing body plans. That’s a necessarily brief overview of the debate, worthy of discussion elsewhere, but the point is that the deep history of body plans can take us to very interesting considerations of evolutionary constraint (or lack thereof). Gould was arguing that evolution left vast tracts of morphospace unexplored, by burning bridges along a herky-jerky path that could have gone just about any other way. Conway Morris wonders if the opposite is the case, that body plans are almost hard-wired into the fabric of biology.
In any case, I think that when evolutionary biologists and embryologists talk of “body plans” they mean deep and fundamental organizational themes that characterize large and ancient sets of lineages. New nasal turbinates are as far as one can get from that. Thanks for a cool topic!
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I suppose I take a Conway Morris approach then.
I should make one revision to my larger point. I think the Cambrian explosion actually is longer than 40 million years, probably closer to 80 million. Perhaps a geologist can help make this more precise? (paging @Joel_Duff, @davidson, and @RyanBebej)
That quote hit my attention too. It references a really fascinating 2008 paper in Science…
The set of viable design elements available for animals to use in building
skeletons has been fully exploited. Analysis of animal skeletons in relation to
the multivariate, theoretical “Skeleton Space” has shown that a large proportion
of these options are used in each phylum. Here, we show that structural
elements deployed in the skeletons of Burgess Shale animals (Middle Cambrian)
incorporate 146 of 182 character pairs defined in this morphospace. Within 15
million years of the appearance of crown groups of phyla with substantial hard
parts, at least 80 percent of skeletal design elements recognized among living
and extinct marine metazoans were exploited.
http://faculty.jsd.claremont.edu/dmcfarlane/bio145mcfarlane/PDFs/cambrian%20designs.pdf
One of the reason I love dealing with this debate is the real gems the conversation continually uncovers. Beautiful paper.
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Oh yes, cool, I remember that paper now, I think I discovered it by reading Conway Morris’ Life’s Solution. I tend to side with Conway Morris on predictability, mostly because of convergence. But even the analysis of “skeleton space” must necessarily ignore other ways of building organisms (sponges? cephalopods? plants?). I wonder if we still know whether evolution burned some bridges on the way to the Precambrian. It seems to me that this is likely in principle.
I certainly agree that conversations like this provide opportunities to rummage through the attic for treasures! Oh, BTW, I don’t know you and have only read a few of your posts here, but thanks for defending science! I look forward to seeing more of your thoughts and your work.
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Nice to meet you too @sfmatheson. Looking forward to getting you know you better. Thanks for linking to your blog too.
I’ve already found the topic of my first post or two: a paper from last month that identifies a single mutation in the human genome that may explain (at least in part) the dramatic expansion of the cerebral cortex that occurred in our lineage
You might be curious to know that we already covered that article! Evolution by splicing . You should post a link to your article there when it is done.
Now returning to the discussion at hand about “body plans.” I noticed some strange irregularities here. Part of it is a misreading of Ross, and the other part what appears to be a mistake in his part. To recap…
Hugh Ross defines body plan as a phyla. First…
a phylum designates life-forms sharing the same basic body plan
Cambrian Explosion Brings Burst of Evidence for Creation - Reasons to Believe
And then he writes in another article…
The Cambrian explosion refers to the sudden, simultaneous appearance of most of the animal phyla (body plans) that occurred 542–543 million years ago.
…
http://www.reasons.org/blogs/todays-new-reason-to-believe/the-cambrian-explosion-and-evolutionists’-responses
But then goes on to make this statement…
Of the 182 animal skeletal designs theoretically permitted by the laws of physics, 146 appear in the Cambrian explosion fossils.
http://www.reasons.org/blogs/todays-new-reason-to-believe/the-cambrian-explosion-and-evolutionists’-responses
He does not reference this claim, but the only candidate article with those two numbers (128 and 146) is the Science article with the abstract…
The set of viable design elements available for animals to use in building
skeletons has been fully exploited. Analysis of animal skeletons in relation to
the multivariate, theoretical “Skeleton Space” has shown that a large proportion
of these options are used in each phylum. Here, we show that structural
elements deployed in the skeletons of Burgess Shale animals (Middle Cambrian)
incorporate 146 of 182 character pairs defined in this morphospace. Within 15
million years of the appearance of crown groups of phyla with substantial hard
parts, at least 80 percent of skeletal design elements recognized among living
and extinct marine metazoans were exploited.
http://faculty.jsd.claremont.edu/dmcfarlane/bio145mcfarlane/PDFs/cambrian%20designs.pdf
Now the first point I now recognize is that I misread Hugh the first time around. He is not saying that skeleton designs are body plans. That is not the case at all. That is something different entirely, in fact the point of the article is that within each phyla a large range of different skeletal designs can be found.
Second, it seems false to reference the “skeletal designs theoretically permitted by the laws of physics.” There is absolutely nothing in this article about the laws of physics limiting the number of designs to 182, and this appears to be Hugh’s invention.
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You can call me Stephen, or maybe Steve after we’ve met at a poster session or something. 
I was afraid I’d been scooped by BL! But there’s plenty more to say about the paper. I’ll post a link here if it doesn’t seem like shameless promotion. I’m writing about the 2015 paper now, then will explain the December paper. I think the story is a an example of overnight birth of a new gene, which should be interesting to everyone. (Except normal people, I admit.)
I don’t read RTB because of its fondness for “invention” as you call it. But I do think that skeleton space is a reasonable approximation of “body plan.” It won’t work for organisms with no skeleton, of course, but it’s a really good start.
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Feel free to start your own dedicated thread. Shameless promotion of science is encouraged. Maybe it will balance out some of the shameless promotion of other things that goes on here. 
(Just click on the +new topic button at the top of the forum home page https://discourse.biologos.org/ )
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Ross is reading the article by Thomas, et al. (2000) incorrectly. The authors state that there are 182 possible pairs of body plan features. However, there are many other combinations: singletons, triplets, quadruplets, etc. So I wrote a little Python script to calculate the number of possible body plans based on Thomas’ taxonomy:
import numpy as np
from itertools import combinations
def multiply_elements(a):
val = 1
for e in a:
val = val * e
return val
features = np.array([2,2,3,4,4,2,3])
plans = 0
for i in range(1,8):
combos = combinations(features, i)
for c in combos:
plans += multiply_elements(c)
print("number of possible body plans =", plans)
# "number of possible body plans = 10799"
10,799 is a lot more than 182! Since there are only about 3 dozen animal phyla in biological history, it would seem that less than 1% of the possible body plans have been explored.
In addition, I’m not sure that a phylum necessarily equates to a body plan as described by ID theorists. For example, the phylum Chordata includes these two species:
Eptatretus stouti (Pacific hagfish) and Homo sapiens sapiens (human)
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@benkirk… Yes yes … but you do remember that the fellow wanted explanations, right? How can body plans just CHANGE?!?
Here you mention that the nostrils on whale embryos are just like ours … and yet genetically, those nostrils are instructed to move!
It is certainly easy enough to explain … proto-whales that suffered genetic mutation for pushing their nostrils around … found great relief when the nostril ended up HIGHER on the head …
What sounds like a strange arrangement to us is just what whales needed.
Do you suppose he will agree that God thought of that?
I really don’t understand how someone who complains that he does believe animals can evolve/speciate with God’s help … and yet at the same time repeats incessantly his objections about this or that change that he just doesn’t believe is possible via Evolution.
It is a senseless set of positions to assert simultaneously !
Phyla are not equated to body plans. There are phylum-level body plans (or perhaps more accurately, phylum-level characters) and there are class- and family-level body plans. Some lineages are named after the characteristic body plan, tetrapods being the most obvious example. Tetrapods are not a phylum.
Take-home message: don’t read RTB.
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Well, they write some great stuff on astrophysics. But biology doesn’t seem to be Ross’ strong suit, I’d agree.
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[quote=“gbrooks9, post:22, topic:29879”]
@benkirk… Yes yes … but you do remember that the fellow wanted explanations, right? How can body plans just CHANGE?!? [/quote]
Hi George,
“Body plan” is just a rhetorical goal post that can be moved anywhere depending on what has been shown to evolve. As a biologist, I would say that there are 2 body plans: protostome and deuterostome.
Sort of, but I’d describe it less anthropomorphically. So which is the real “body plan”–before or after the nostrils move? Or does that mean that one organism has two body plans?
It’s just hopelessly vague, which is why it is a favorite rhetorical weapon of denialists.
I have no idea what you mean. How can any organism “suffer genetic mutation for pushing their nostrils” or anything else? Those verbs and nouns don’t go together.
Moreover, by invoking mutation, you’re again forgetting the relative amounts of existing variation and new variation (mutations). What is that ratio again?
I have no idea. It would seem that if an omnipotent God thought of that, there’s no reason to have the nostrils move. He would just build them in the place where they are in the adult. Evolution, OTOH, works very differently.
Cognitive dissonance.
[quote]It is a senseless set of positions to assert simultaneously !
[/quote]Like asserting that new mutations must account for things like this, given the known fact of the ratio between existing genetic variation and new mutations! 
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I think it is a bit more complicated than this.
There is a real concept lurking here. I think we all agree that there were a large number of different “body types” that appear in the Cambrian explosion. I do not think it is “all possible permitted by physics”, but there were certainly a lot, and more than we see walking (or swimming and flying) around today.
I think that is the key point, which is real, that is being referred to when Gould, Morris, and Hugh Ross (yes him too!) talk about “body plans.” Though, I do not think there is a good way to get much more specific than this.
As for the point about tetrapods being a “new body plan”. I don’t think a definition that includes tetrapods is really relevant here. It is clear that tetrapods are just a tweaked body plan from something that came before that looked very very similar. I think the point of “novel” body plans is that they do not have any obvious (even they do exist) precursors.
Of course, we can talk about the non-obvious precursors and we can even debate whether or not any body plans truly are “novel.” I think evolutionists, for the most part, would argue almost all body plans are not novel. Hugh Ross I am sure would key on specific cases (or classes of cases like the the Cambrian Explosion) where the specific precursors are less clear.
So I do think that “body plans” is a real concept even if a precise definition is elusive. I would say that the difficulty in defining them is part of the point too. The more fossils we see, the weaker the divisions seem.
And this article is extremely helpful…
I think I’m the one who mentioned tetrapods, and I wrote a whole series about their evolution right here on BL. I didn’t say that they represent a “new body plan,” and certainly never would claim that the tetrapod body plan (or any other body plan) arose without precursors. No, the point was that “body plan” is a phrase that does not mean “phylum” any more than it means “class” (tetrapods are a class, technically a superclass) or “family”, both of which are taxonomic categories that are often identifiable specifically by body plan. The Tiktaalik paper, describing one of the most famous fossil finds of our time, is titled “A Devonian tetrapod-like fish and the evolution of the tetrapod body plan.”
The tetrapod body plan, like everything else in the biological world, was new at some point in history. How it arose and why/how/if it has been successful — those are worthy and interesting questions. Whether it or anything else poofed into existence is not, to me, any more worthy a question than the Omphalos hypothesis. YMMV.
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Oh, it is more complicated, which is my (badly articulated) point. However, it’s not complicated as a rhetorical tool in the hands of a pseudoscientist.
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As we know … the snail and the octopus are both members of the Phylum “Mollusca” !!!
And so they share a common ancestor… the first mollusk… whatever it was.
The Octopus has 8 limbs… the snail? Does it even have ANY limbs?
The Octopus has 2 prominent eyes and a highly developed brain. The snail? A very different kind of brain (if we can call it that) … and while it has eyes … are they at all like the eyes of an octopus?
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