Plant and animal development compared

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Since I wrote about the wacky creationist who couldn't wrap his mind around the idea that plants and animals are related, and since I generally do a poor job of discussing that important kingdom of the plants (I admit it, I'm a metazoan bigot…but I do try to overcome my biases), I thought I'd briefly mention an older review by Elliot Meyerowitz that compares developmental processes in plants and animals. The main message is that developmental processes, the mechanisms that assemble the multicellular whole, are very different in the two groups and are non-homologous, but don't get confused: the basic cellular processes are homologous, and there's no doubt that we are related. The emphasis in this paper, though, is the evidence that plants and animals independently evolved multicellular developmental strategies. There is some convergence, but the tools in the toolbox are different.

Continue reading "Plant and animal development compared" (on Pharyngula)

36 Comments

Thank you, thank you, thank you! I’ve been looking for this information ever since I saw that guy last week :-)

(And thanks for putting it on You Tube as well - it will make it so much easier for me to forward this to family as well :-) )

metazoan bigot… ————

Sweet use of technical vernacular.

Enjoy.

bigoted indeed. and eukaryocentric to boot.

:)

(I admit it, I’m a metazoan bigot…but I do try to overcome my biases),

Ah, but how do you feel about fungi? ;)

Henry

I am disappointed that there is no comment section for Timothy Sandefeur’s post, neither here nor at his own blog. Because of that, I am forced to post here, in the wrong thread.

I appreciate everyone who defends valid science.

However, doing so should not give anyone license to use this venue to advertise a particular political view without allowing comments.

If Mr Sandefeur is to be given a reward for his service to science education, it should come in the form or an award or acknowledgment, not in the form of giving him, and no-one else, license to present his political views, without possibility of reader comment.

I recognize that the immediate subject of his post is a negative review of a “libertarian” book, but the underlying assumption of the post is that libertarianism is “right” but this particular book is bad. This amounts to a rather strong advocacy position for libertarianism.

The nations with the best science and technology, the healthiest populations, the best defense of human rights, and the strongest economies, that is to say, most of Western Europe, Canada, Australia, Japan, for now the United States, and scattered others, all utilize strongly-regulated market economies with strong social safety nets. No human society has ever existed which achieved these goals under “libertarianism”.

Publicly funded education, the affairs of which are the very raison d’etre of this blog, was an early and valuable innovation that was strongly associated with the development of science and technology. Libertarians tend to oppose public education. I don’t know if Mr Sandefeur opposes public education, or if he merely chooses to label himself as a type of political extremist who often does so.

It is most ironic that Mr Sandefeur at least creates the impression that biology, or the theory of evolution, in some way lends support to the political extremist position “libertarianism”. It is transparently clear that no one political ideology can be said to be more compatible with biology or the theory of evolution than others. All political ideologies were equally created by “natural” humans.

Mr Sandefeur inaccurately associates the defense of markets with libertarianism, as if the two always went together. In fact, I am a strong advocate of markets myself, albeit with appropriate socially cooperative regulation where necessary. It is disingenuous to even suggest that support for “markets”, an extraordinarily common attitude that cuts across many political viewpoints and ideologies, is exclusively or even especially the province of “libertarianism”. To put it another way, almost everyone supports “markets”, and most people would be appalled by the more extreme aspects of libertarianism.

It is also ironic that, given the numerous well-targeted criticisms of UD and other creationist sites, for their not allowing critical comments, Mr Sandefeur should be blithely rewarded with a comment-free bully pulpit to preach his own political extremism, at this very site. Indeed, he takes it a step further than UD. No need to delete critical comments, when comments are not allowed at all.

I support the right of anyone to hold any political beliefs they wish, independently of their correct or incorrect understanding of biological evolution. Political viewpoints are related to subjective judgments. Some scientific study of the objective measurable effects of certain types of systems is possible, but of course, it is subjective whether said effects are “good” or “bad”.

Mr Sandefeur may well believe that the inevitable effects of more or less entirely eliminating the infrastructure of public health, public education, publicly funded law enforcement, publicly funded fire control, social programs for the needy, and so on, or at least of massively curtailing these cooperative institutions, would be “good”, even while understanding perfectly well, perhaps at a private and secretive level, what the impact, in human suffering, would be. I would disagree that the impact of abandoning or massively curtailing all social cooperation would be “good” - and my subjective disagreement would be very, very, very, very strong indeed.

But it is this very subjectivity that must make us aware that no political viewpoint can be anointed as the “scientific” one.

However, it is worth noting that science and science education thrive almost exclusively where they are supported by tax-funded, strong, cooperative public institutions. Thus, while I cannot say that it is “unscientific” to subjectively prefer a world in which there would be few or no socially cooperative institutions, I can say that it is somewhat illogical to declare oneself an advocate of science and science education on one hand, and of “libertarianism” on the other hand. Libertarianism may not be “unscientific”, but if put into practice, it would be most detrimental to the progress of science.

Let me fully clarify that I strongly support the right of libertarians to post, to draw attention to their political views where relevant, and to defend those views. I merely request that the rest of us be given the opportunity to comment, as well, if not here, then at least at the original blog. It is grossly unfair to allow advocacy one specific political ideology in a comment-free format.

Since Timothy disabled comments everywhere in the next posting, I have to comment here. I basically thank him for ripping Shermer a new one. But he and other reviewers forgot to mention one crucial point. Shermer says that free markets are good because they’re “like” evolution, and evolution brings order out of chaos etc. (no, seriously, he does say a thing this silly, see http://www.cato.org/event.php?eventid=4297 at 15:24).

The problem is… evolution does NOT produce optimal “design”! That is actually one of the points against ID - if organisms were designed, the designer must’ve been inept. So is this an argument FOR the free market, or, perhaps, AGAINST it?

Ah, but how do you feel about fungi? ;)

Yummy in pepper-cream sauce, over fettuccine.

Long may Her Noodly Appendage wave.

Well, well.

I was going to object to the non-comment blog post as well, but now I sympathize with the poster - the subject seems to elicit unsupportable arguments, rather like the book he reviews. harold comments:

It is also ironic that, given the numerous well-targeted criticisms of UD and other creationist sites, for their not allowing critical comments, Mr Sandefeur should be blithely rewarded with a comment-free bully pulpit to preach his own political extremism, at this very site.

As PT is commonly used to “preach” forms of what then must be termed religious or philosophical “extremism”, this amounts to saying that this is bad practice. I don’t think so.

This is however eminently supportive, given that fairness implies a certain moral aspect of the communicative media that is internet:

It is grossly unfair to allow advocacy one specific political ideology in a comment-free format.

I also note that “libertarianism” seems to be a heterogeneous mass of philosophical and political views, and can probably not be analyzed and criticized en masse, without defining the terms and contexts. In fact, there is a real problem to get to know the views and understand the critic because of such reactions.

(But if the posted review is correct, Shermer is rather uncritical for a skeptic. It raises the question to me if he is irreligious by name only, still adopting his later found views on faith?)

And what was my own reason to object to the comment-free format? (Besides the unfairness, that is.) Well, I think “chock full” is misspelled. And if it is, it seriously messes with my languages, as “shock” is “chock” in swedish but “chock” has no (non-nautical) equivalence.

Btw, speaking of misspellings, it is “Sandefur”.

As PT is commonly used to “preach” forms of what then must be termed religious or philosophical “extremism”, this amounts to saying that this is bad practice. I don’t think so.

Did you miss the critical phrase “comment-free” in what you quoted? Harold did not say that preaching, or even preaching extremism, is bad practice, he was very explicit that only preventing comments is bad practice; the rest of his post was his own personal response to the content. You’re not usually a fool, Torbjörn, but this takes the cake.

stevaroni:

Ah, but how do you feel about fungi? ;)

Yummy in pepper-cream sauce, over fettuccine.

I can take metazoan bigotry.

And eukaryocentricity as well.

But eating your own forty billionth cousin? When will this madness end?

evolution brings order out of chaos

What utter nonsense (not unusual for Shermer). Birds are no less chaotic than dinosaurs and whales are no less chaotic than Pakicetus, etc. ad infinitum.

The closing paragraph of my earlier post was…

Let me fully clarify that I strongly support the right of libertarians to post, to draw attention to their political views where relevant, and to defend those views. I merely request that the rest of us be given the opportunity to comment, as well, if not here, then at least at the original blog. It is grossly unfair to allow advocacy one specific political ideology in a comment-free format.

This clearly confirms that PG’s interpretation of my post was 100% correct, and that Tobjorn may have mildly misinterpreted. Again, politics is often relevant here. The strong association of creationism and ID with a single political party and ideology is obvious, for example. It is and was the lack of ability to comment that infuriated and continues to infuriate me.

I will wait to see how this develops, but I want to make on thing clear…

Allowing UD-style, uncriticizable posts, on controversial political topics, by a select few, is a policy that will radically lower, arguably “ruin”, the quality and reputation of this blog.

Either open up a comments section, take the Sandefeur post down, or concede that this is not a truly open forum, and that some contributors are rewarded with Dembski-style sheltered posts, with comments relegated to a “free speech zone” of other threads.

Ironically, the Sandefeur post is quite good in many ways and a very valid post for PT. You aren’t doing Sandefeur or the blog any favors by giving it the hot house orchid treatment. The vast majority of people are aware that the stifling of critical speech implies insecurity, brittle egotism, and mental conflict on the part of the stifler.

Now a Scientific Question -

By the way, I have wanted to ask this question since I saw PZ’s post on this subject, and I am not entirely thrilled that I had to fill up this comment section with protests.

The two most basic differences between plant and animal cells that I recall (*with the caveat that I am sadly another metazoan bigot who doesn’t know enough about plants*) are that most plant cells have cell walls, and that many plant cells contain energy-harvesting chloroplasts.

PZ’s article seems to show that the proto-plant lineage separated before chloroplasts, and that fungi, which also have cell walls (similar to those of plants?) separated from animals later.

Are there any intelligent conjectures as to how early proto-plant cells would have differed from the earliest committed animal-lineage cells?

Torbjörn Larsson, OM:

Well, I think “chock full” is misspelled. And if it is, it seriously messes with my languages, as “shock” is “chock” in swedish but “chock” has no (non-nautical) equivalence.

Full to the limit; as full as possible.

http://www.thefreedictionary.com/chock-full

http://tolweb.org/Eukaryotes/3

PZ’s article seems to show that the proto-plant lineage separated before chloroplasts, and that fungi, which also have cell walls (similar to those of plants?) separated from animals later.

Don’t know about cell walls, but http://tolweb.org/Fungi/2377 says

They share with animals the ability to export hydrolytic enzymes that break down biopolymers, which can be absorbed for nutrition.

But where most animals (spiders being a notable exception) do their digesting inside their bodies, fungi do it on the outside.

Henry

This seems to be the place for comments on Sandefur’s post about Shermer’s book, which does not allow comments. So maybe someone could pass this on to him:

It’s “oxytocin,” not “oxycotin.”

Henry J. -

Thanks, although actually, I already knew that about fungi. Some plants, Venus Flytraps and the like, can secrete enzymes for extracellular digestion of large biochemicals.

It was actually easy to learn that fungal cell walls, where present, are completely different from plant cell walls. Mildly embarrassing that I didn’t google first. Of interest, fungal cell walls contain chitin. Also, since fungi are occasional pathogens, I probably should have known this anyway. http://en.wikipedia.org/wiki/Cell_wall

I’m still curious about what the fundamental energy source of a pre-chloroplast plant lineage cell would have been, and how that cell would have differed from animal/fungal lineage cells in existence at the same time.

What I’d like to know is if the two types of cells diverged so early, before the inclusion of chloroplasts,and as someone said before multicellularity, why do both plants and animals have nearly the same meiotic division patterns? Would these not have evolved differently if they evolved seperately? I would think the eukaryotic seperations must have occurred after the evolution of “sexual” reproduction.

why do both plants and animals have nearly the same meiotic division patterns?

I believe all eukaryotes are fundamentally diploid or otherwise polyploid. Haploid life cycle phases, as seen in some Hymenoptera lineages, are, I believe, secondary. (Support - http://courses.biology.utah.edu/wil[…]s/Drlica.pdf)

It would therefore seem that there were ancient eukaryotic cells, capable of meiosis, and that there was an irreversible lineage separation, with plant ancestor cells diverging from metazoan ancestor cells. However, it would seem that this occurred before the development of chloroplasts. It’s also true that plant cellulose cell walls don’t seem to be found in any other lineage, and thus presumably came later. And the whole point of the article was that this occurred before the evolution of true multicellularity in these lineages, although there was subsequent convergent evolution of that trait, through different mechanisms.

So I’m still mighty curious about these unicellular, non-photosythesizing, probably cellulose-free plant ancestor cells, and how they were different from metazoan ancestor cells present at the same time.

Rather like ID is a euphemism for creationism I find libertarianism is a euphemism for anarchy.

The cell phone is a perfect example of libertarianism not working. Give people a new toy and they find ways to use it to inflict abuse on other people.

Well, a day has passed and neither Sandefeur nor the staff of PT has acknowledged the civil requests to comment on Sandefeur’s article.

Now I must resort to that form of language that always gets a response - the language of well-aimed mockery and ridicule.

PT, you make HYPOCRITES and FOOLS of yourselves to allow no-comment posts. How many millions of words of scorn have been directed at creationists for deleting unfavorable comments? But now PT endorses an even more grotesque form of cowardice, that of not even allowing comments in the first place!

It’s obvious what happened. Sandefeur rightfully requested some acknowledgment for his valid services to the site and to the cause. And I support that general principle. Give him a cake, give him an award, give him a side-bar link to his blog, hell, give him money for all I care.

Sadly, the privilege which Sandefeur seems to have requested is a shameful and inappropriate one. He was given the privilege of turning PT, which boasts of being a venue for free intellectual discourse, into a closed, comment-free soap-box for his own little political theories.

Sandafeur, do you understand what a fool and hypocrite you look like putting up comment-blocked stuff even as you boast of being a “libertarian”? There is only one response to he who screeches “liberty” while shutting down the expression of others, and that response is

BWAHAHAHAHAHAHAHAHAHAHAHA!!!!!!!!!!!

Why has there been no acknowledgment of the request for comments? Are you too busy? What are you doing - hatching a batch of eggs? Because you’re a chicken! AWK-BOK-BOK-BOK! What are you afraid of…Colonel Sanders?

harold — Maybe just because it is President’s Day?

Hmmm?

Continuing where Sandefur shouldn’t have left off…

I’ve read several of Shermer’s books, and I think Timothy is half-correct in his complaint. Shermer has a very annoying habit of researching and explaining in clear depth how things he disagrees with are wrong, misleading, or incomplete, BUT swallowing even the most hazily suggestive material as unquestioned gospel where it supports his argument or his preferences.

After parroting Shermer’s sources a few times, only to find that they have been substantially modified if not outright discredited by subsequent research, I’ve learned to be very very leery of his presentations. Especially when I find that the corrective material was available easily in time for Shermer to have considered it before committing to publication.

In general, if Shermer finds something he can interpret to fit his argument’s overall structure, even if its only suggestive or tentative, they he just assumes it must be solid. The care he takes to dismantle what does NOT fit his picture shows that he’s capable of doing this sort of analysis, and OUGHT to suggest to him that maybe he’d be more persuasive applying this level of rigor to stuff he wants to hear as well.

Shermer strikes me as a debater rather than an explainer.

harold:

Well, a day has passed and neither Sandefeur nor the staff of PT has acknowledged the civil requests to comment on Sandefeur’s article.

Mr Sandefur has elected not to enable comments either here or at his own blog. He has, however, left trackbacks enabled in both places. This would suggest that he is looking to encourage responses in the form of full articles, rather than the hit-and-run point-scoring style (with mythical Scandanavian troglodytes) that goes on the comments here.

In any case, switching the comments off altogether is a lot more honest than the selective trimming of adverse comments that goes on over at the home of the Explanatory Filter.

Mr Sandefur has elected not to enable comments either here or at his own blog.

Correct, and this is embarrassing. I don’t care what he does at his own blog, but the tradition on PT, for years, has been to allow free and immediate reader comments. The very claim of PT to be a forum for open discussion of scientific issues and questions is grounded in this format. Since Mr Sandefeur has linked to his own blog, allowing comments there would be an adequate substitute to allowing them here, if suboptimal. But he has done neither.

He has, however, left trackbacks enabled in both places. This would suggest that he is looking to encourage responses in the form of full articles, rather than the hit-and-run point-scoring style (with mythical Scandanavian troglodytes) that goes on the comments here.

In the first place, there is no logical connection; allowing comments would not inhibit “full articles”, and disabling them is not a logical mechanism to encourage “full articles”. Trackbacks are an excellent feature - at least Sandefeur didn’t disable them - but they do not conflict with comments. Thus, this argument is essentially a non-sequitor.

I’ve noticed that creationists and others who seek to evade honest discussion often make similar claims. “I wasn’t trying to block criticism, it’s merely that I’m so special and elite that only certain forms of criticism will do.” Of course, the specific type or form of criticism demanded is invariably some sort of format that creates a boundary, delay, or inconvenience for the critic.

Furthermore, if Sandefeur especially wanted responses in the form of full articles, he could simply have directly asked readers to consider preparing full articles. Why not say what you want? There is no need for a ludicrous Rube Goldberg strategy of blocking comments but leaving trackbacks, in the hopes that this will indirectly “encourage full articles”.

Ironically, I may just put together an “article” on this incident and submit it to PT.

In any case, switching the comments off altogether is a lot more honest than the selective trimming of adverse comments that goes on over at the home of the Explanatory Filter.

I’m inclined to disagree.

However, of course, it is a subjective decision as to which is “more dishonest”. At best, you argue here that Sandefeur’s behavior is not as bad as Dembski’s behavior, a rather weak defense indeed.

Whichever is “more dishonest”, it creates a strong odor of hypocrisy for this blog to endlessly (and justifiably) critique Dembski for manipulating comments on one hand, and then suddenly start putting up articles that don’t allow comments at all on the other hand.

Open comments allow open, free, and immediate discussion. This is a very well-moderated forum. There is no convincing rationale for disabling comments.

My personal choice to take up the study of science, as an undergraduate, was partially the result of my frustration with fields of study that permitted instructors to pontificate in the absence of evidence or rationale, dismiss questions and criticisms, and implicitly present their views as arguments from authority (it was also the the result of my nerdly curiosity about scientific topics, of course). Scientists don’t have those luxuries, much as some, especially aging Nobel laureates, may wish they did. It is not “pro-science” to shelter one’s ideas from criticism.

I should add that I am aware that Sandefeur has done much to further good science education and combat creationist nonsense. I’m not in any way trying to take away from the good he has done in the past, even if he is a “libertarian”. Nor, as I said, does it matter how he handles comments at his own blog. But it is a mistake for PT to allow comment blocking, and a bigger mistake for them to allow selective comment-blocking by members of an “elite”.

No, I think Timmy considers discussion to be, you know, plebian and scruffy. He has delivered unto us the One True Opinion, so well expressed that valid dissent is impossible and suggested improvements are incorrect. Besides, allowing comments implies that he’ll stop by from time to time to (yuck!) wallow through them and perhaps actually respond. The very fact that some people have time to make comments simply shows that their time isn’t nearly so valuable anyway.

He has delivered unto us the One True Opinion, so well expressed that valid dissent is impossible and suggested improvements are incorrect.

Say, that reminds me of another guy. Bill something. I’m blocking on it…something with a “D”…Demwit? Dumbski? Donkey? Something like that. I think he used to work at Baylor.

So, Harold, care to explain why you’re distorting Sandefur’s surname, EVEN AFTER IT HAS BEEN POINTED OUT TO YOU?

BWAHAHAHAHAHAHAHAHAHAHAHA!!!!!!!!!!!

I see Sandefur has corrected the spelling of oxytocin. I take full credit.

So, Harold, care to explain why you’re distorting Sandefur’s surname, EVEN AFTER IT HAS BEEN POINTED OUT TO YOU?

BWAHAHAHAHAHAHAHAHAHAHAHA!!!!!!!!!!!

This is actually a more coherent defense of Sandefur than the “he secretly wanted to encourage ‘full articles’ so he disabled comments as a strategy to do that” nonsense that was attempted above.

Did you miss the critical phrase “comment-free” in what you quoted?

Why would you think that, as I made sure to discuss it?

If you remove “preach” and “extremism” (or “one specific political ideology”, addressing harold’s comment #143372 - but that is an acceptable characterization), what remains to be awarded?

Oh, and I don’t think it “takes the cake”. Not allowing comments is pretty fubar.

Btw, seems AtBC has opened up for any further commenting on this.

Full to the limit; as full as possible.

Oh, thank you, thank you! Not only did I miss to search it (shockingly), that explains even more of my confusion here (I’m chock full of it [yes, I know - but it kinda fits here :-P]).

Do fungi and animals have homologous mechanisms (i.e. inherited from their common ancestor) for multicellularity, or did each of them develop its own?

(Of course, this question runs the risk of interrupting the ongoing argument about a different thread, but what the heck.)

Henry

Fungi and animals also differ. One key element: the receptor tyrosine kinases (RTKs). Animals have them, plants don’t, and as it turns out, Dictyostelium doesn’t either.

As this post tries to argue, there might well be similarities in developmental logic, even if the components differ.

Looking at the tree-of-life site page http://tolweb.org/Choanoflagellates/2375 I noticed something interesting-

In addition to their critical ecological roles, choanoflagellates are of particular interest to evolutionary biologists studying the origins of multicellularity in animals. As one of the closest living relatives of animals, choanoflagellates serve as a useful model for reconstructions of the last unicellular ancestor of animals.

Not only that, but these guys have flagella, too! (Wait, is that good or bad?)

Henry

Not only that, but these guys have flagella, too

Eukaryotic flagella are quite different from bacterial flagella. And much larger. It is a case of convergent evolution.

http://en.wikipedia.org/wiki/Flagellum

As for this…

(Of course, this question runs the risk of interrupting the ongoing argument about a different thread, but what the heck.)

I give up and this is my final comment.

I continue to be amazed and disappointed at the lame response of PT (including the grudging “after the bar closes” nonsense, at which my account is personally banned from commenting, and which is headed by what amounts to a warning not to discuss the relevant features of Sandefur’s post). The favoritism and defensiveness displayed in this incident can only serve PT ill. Hopefully this is an isolated incident.

If someone has an inflammatory “economic philosophy” which they are afraid to defend in free and open conversation, then the best solution is not to put up posts which are grounded in that “economic philosophy” in the first place.

Those who cannot defend their own views in an open forum should probably keep said views to themselves in the first place, and should also question their own ethical convictions. If you cannot defend it to a critic, can you really defend it to yourself? But enough. For now, PT is the primary venue for biology education news, and until that changes, and/or until I am banned, I will probably continue to visit here.

I am going with what wiki said. That aobut does it for me.

About this Entry

This page contains a single entry by PZ Myers published on February 17, 2008 10:58 AM.

Flagellum evolution in New Scientist was the previous entry in this blog.

My review of Michael Shermer’s The Mind of The Market is the next entry in this blog.

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