Ernst Haeckel's embryological diagrams and biology textbooks

[randman]

Except the hourglass model is still taught. You just don't want to look at the data.

 

[Lowpro]

Except the hourglass model is still taught. You just don't want to look at the data.

You know at this point I have no idea what you're talking about; the hourglass model wasn't taught to me nor is it taught at all in evolutionary studies but it seems to me as if you want to repeat the Haeckel argument all over again.

I'm going to make a prediction.

1) The Hourglass Theory exists
2) It's not completely valid but many parts of evolution fit the data
3) The rest of the data can still be explained because the Hourglass Theory is not requires to explain the data in the first place, for ALL of the data, not just the part that it cannot explain.


I don't know much about the Hourglass Theory on the whole so I'll have to study up.

 

[randman]

Does it fit, however. Please respond to my points on greater differences in the earliest stages of embryonic development which suggest any later claims of more conserved stages would best be evidence of convergent development rather than shared ancestry.

 

[Cainkane1]

You know at this point I have no idea what you're talking about; the hourglass model wasn't taught to me nor is it taught at all in evolutionary studies but it seems to me as if you want to repeat the Haeckel argument all over again.

I'm going to make a prediction.

1) The Hourglass Theory exists
2) It's not completely valid but many parts of evolution fit the data
3) The rest of the data can still be explained because the Hourglass Theory is not requires to explain the data in the first place, for ALL of the data, not just the part that it cannot explain.


I don't know much about the Hourglass Theory on the whole so I'll have to study up.

http://en.wikipedia.org/wiki/Research I could only find this on wiki. It seems that instead of being a theory its a research method not an actual theory. However randman even if what you say is true the theory of evolution via mutation and natural selection is sound and has been proven in many other ways to the extent that there are no scientific arguments against it.
Haeckel died in 1919 and while he was an eminent scientist he may have been wrong in many ways but be that as it may he has more scientific credibility than ID.

I graduated college in 1969 and I had to take two biology courses and I never even heard of the hourglass theory.

 

[A'isha]

Perhaps, randman, you can explain how this 2007 paper finding evidence for a conserved phylotypic stage in mice relies on Haeckel's drawings or theories in any way, shape, or form.

Please be specific, since the paper makes a point to completely ignore morphology and instead focuses on "explor[ing] a comprehensive quantitative method for defining the constrained stage using expressed sequence tag (EST) data, gene ontologies (GO), and available genomes of various animals."

 

[A'isha]

You know at this point I have no idea what you're talking about; the hourglass model wasn't taught to me nor is it taught at all in evolutionary studies but it seems to me as if you want to repeat the Haeckel argument all over again.

I'm going to make a prediction.

1) The Hourglass Theory exists
2) It's not completely valid but many parts of evolution fit the data
3) The rest of the data can still be explained because the Hourglass Theory is not requires to explain the data in the first place, for ALL of the data, not just the part that it cannot explain.


I don't know much about the Hourglass Theory on the whole so I'll have to study up.

The "hourglass theory" has been a controversial topic. Part of the reason why some people have heard of it and others haven't is that until recently, there were two camps on opposite sides of the issue. Richardson's 1997 paper dealt a blow to the pro-phylotpic side when he pointed out the dangers of using morphological comparisons (especially given the sizes of what's being compared). However, since Haeckel's diagrams are useless as evidence for that stage, and straight embryo morphology comparisons can be subjective based on the person making the comparison (which is why there was a controversy in the first place), science has naturally turned to other, far less subjective methods - genetic methods.

Things such as the paper I linked above and this recent article in Nature are pretty strong evidence for phylotypic stages. And, unfortunately for randman, they don't have anything whatsoever to do with Haeckel and his drawings.

 

[randman]

Perhaps, randman, you can explain how this 2007 paper finding evidence for a conserved phylotypic stage in mice relies on Haeckel's drawings or theories in any way, shape, or form.

Please be specific, since the paper makes a point to completely ignore morphology and instead focuses on "explor[ing] a comprehensive quantitative method for defining the constrained stage using expressed sequence tag (EST) data, gene ontologies (GO), and available genomes of various animals."

So do evos claim the hourglass model aka the phyloptypic stage or is Lowpro right in saying they do not?

I'd love to answer you but I want you to first clear up some misconceptions and set the record straight so your followers like Lowpro understand what sort of claims you are making and those you are not.

I also would like a response to my earlier post explaining why the hourglass model is evidence against evo theory.

 

[randman]

Let me break it down further. Many evos say the hourglass model aka the phylotypic stage is evidence for common ancestry. The evidence indicates the hourglass model is incorrect but some try to argue for it.

However, evos miss the point that the hourglass model is actually evidence against common descent and ancestry. The reason is they admit embryos start out very different; hence the wide brim of the top of the hourglass, but say they converge into a more similar stage.

Now, let's think about that for a minute and use the illustration of so-called convergent evolution, which is really just evidence for common design. When creatures are considered to have started out on a path markedly different but similar features appear, evos say this is an example of convergent or parallel evolution because since earlier in their proposed evolutionary history, they were different having very different ancestors according to evos.

In other words, the concept of being different at the beginning is used to say the similarities are not the result of common ancestry passing down similar traits but that these traits arose independently.

However, it does not occur to them that since the hourglass model indicates differences early on in development, that indicates a break in evolutionary history such that any later similarities, which is often overblown and non-factual, would be evidence for convergent development not common ancestry.

Otherwise, the earlier stages should be more similar, not less so.

Now evos can shout this is akin to being a Holocaust denier but it's actually just data-driven analysis, something evos ought to try sometimes.

ANTpo, read my post above. Can't wait for you and other evos to backtrack and say the hourglass model doesn't really matter anyway, already happened with Lowpro.

 

[Cainkane1]

ANTpo, read my post above. Can't wait for you and other evos to backtrack and say the hourglass model doesn't really matter anyway, already happened with Lowpro.

What is this hourgass method anyway? I tried to look it up on wikipedia and it seems to refer to a research method rather than a theory concerning evolution alone. So indulge me and some of the others and tell us what you think it is and how it relates to evolution.

 

[A'isha]

So do evos claim the hourglass model aka the phyloptypic stage or is Lowpro right in saying they do not?

I'd love to answer you but I want you to first clear up some misconceptions and set the record straight so your followers like Lowpro understand what sort of claims you are making and those you are not.

Evolutionary theory, itself, evolves, randman. As scientists learn new things and explore the ramifications of what they already know, they reconsider their theories in the light of those new discoveries, and make adjustments accordingly. This is, pretty much by definition, how science works.

Previously, the phylotypic stage was only identified morphologically, through direct comparative embryology. The "hourglass theory" that arose out of this has been contested in evolution (especially, though not solely, post-Richardson). Not least of the roots of the controversy was the fact that trying to identify significant similarities in small embryonic structures can be influenced to a lesser or greater degree by one's subjective views. As a result, it's not at all surprising that depending on what side of the debate you and/or your professors ended up on, you'd be either familiar or unfamiliar with the theory.

What was needed was a better set of data for the phylotypic stage, and one that was not subject to the flaws of morphological comparisons. One of the explicit goals of the above linked paper's authors was to do just that, and the paper is their evidence for a conserved phylotypic stage based on molecular data, a new data set for the "hourglass theory" that is totally seperate from and unreliant on the old, doubtful morphological data sets.

ANTpo, read my post above. Can't wait for you and other evos to backtrack and say the hourglass model doesn't really matter anyway, already happened with Lowpro.

Maybe this was a problem back when the only evidence for it was comparing embryo drawings and photographs. Now that there's a growing body of genetic evidence for the phylotypic stage, scientists no longer have to rely on pictures, and have an additional array of tools to compare this genetic data with other genetic data. They can even (as the paper's authors did) use those tools to identify multiple "hourglasses", representing different ancestral lines, and the fact that these genes are conserved from ancestors rather than evolved separately can be checked by looking at their ancestor index data.

 

[Lowpro]

ANTpo, read my post above. Can't wait for you and other evos to backtrack and say the hourglass model doesn't really matter anyway, already happened with Lowpro.

Man you're a liar...

There was no backtracking, I said very explicitly that doesn't require the hourglass model to work, it would require evidence of a phylotypic stage, much like what ANTpogo linked you.

If anything I've mentioned that I don't know much about the Hourglass Theory the only mention I made was my prediction:

You know at this point I have no idea what you're talking about; the hourglass model wasn't taught to me nor is it taught at all in evolutionary studies but it seems to me as if you want to repeat the Haeckel argument all over again.

I'm going to make a prediction.

1) The Hourglass Theory exists
2) It's not completely valid but many parts of evolution fit the data
3) The rest of the data can still be explained because the Hourglass Theory is not requires to explain the data in the first place, for ALL of the data, not just the part that it cannot explain.


I don't know much about the Hourglass Theory on the whole so I'll have to study up.

I don't know what you consider backtracking but I assure you I didn't backtrack, but your deliberate misinterpretation of what I said is noted and will be used against you.

Another bit of what I said:

... I really can't believe your ignorance it is killing me.

The overall hourglass model isn't part of evolution and development; it's not required. It's a blanket concept where some parts of what is actually tested rings true (IE it's no invalidated) but it's not an accepted "always" rule of evolution. It doesn't need to be. It isn't taught because it's not relevant; evolution doesn't require it, but it's nice to compare it to. Is it correct? probably not but does it reflect contemporary evolutionary theory? Hell no. Perhaps you'd like to consider what reality has to say about how embryonic theory works...

As for the latter part of your statement, remember that time I told you how you had all this rope to hang yourself with? You gave yourself a few more feet...

You know what IS evidence for the phylotypic stage?

something like this

And you didn't even need the Hourglass Model to get there...but the model is indeed interesting.

You're trying your hardest to conflate phylotypic stage with the Hourglass Model to pretend they require each other. I've only ever said they don't, but they indeed are related.

 

[randman]

Evolutionary theory, itself, evolves, randman. As scientists learn new things and explore the ramifications of what they already know, they reconsider their theories in the light of those new discoveries, and make adjustments accordingly. This is, pretty much by definition, how science works.

Previously, the phylotypic stage was only identified morphologically, through direct comparative embryology. The "hourglass theory" that arose out of this has been contested in evolution (especially, though not solely, post-Richardson). Not least of the roots of the controversy was the fact that trying to identify significant similarities in small embryonic structures can be influenced to a lesser or greater degree by one's subjective views. As a result, it's not at all surprising that depending on what side of the debate you and/or your professors ended up on, you'd be either familiar or unfamiliar with the theory.

What was needed was a better set of data for the phylotypic stage, and one that was not subject to the flaws of morphological comparisons. One of the explicit goals of the above linked paper's authors was to do just that, and the paper is their evidence for a conserved phylotypic stage based on molecular data, a new data set for the "hourglass theory" that is totally seperate from and unreliant on the old, doubtful morphological data sets.



Maybe this was a problem back when the only evidence for it was comparing embryo drawings and photographs. Now that there's a growing body of genetic evidence for the phylotypic stage, scientists no longer have to rely on pictures, and have an additional array of tools to compare this genetic data with other genetic data. They can even (as the paper's authors did) use those tools to identify multiple "hourglasses", representing different ancestral lines, and the fact that these genes are conserved from ancestors rather than evolved separately can be checked by looking at their ancestor index data.

Ok, so you claim the hourglass model aka the phylotypic stage is correct.

How do you account for the fact it is evidence against evo theory, not for it?

 

[randman]

Anyone even going to try to answer the data and analysis here?
Let me break it down further. Many evos say the hourglass model aka the phylotypic stage is evidence for common ancestry. The evidence indicates the hourglass model is incorrect but some try to argue for it.

However, evos miss the point that the hourglass model is actually evidence against common descent and ancestry. The reason is they admit embryos start out very different; hence the wide brim of the top of the hourglass, but say they converge into a more similar stage.

Now, let's think about that for a minute and use the illustration of so-called convergent evolution, which is really just evidence for common design. When creatures are considered to have started out on a path markedly different but similar features appear, evos say this is an example of convergent or parallel evolution because since earlier in their proposed evolutionary history, they were different having very different ancestors according to evos.

In other words, the concept of being different at the beginning is used to say the similarities are not the result of common ancestry passing down similar traits but that these traits arose independently.

However, it does not occur to them that since the hourglass model indicates differences early on in development, that indicates a break in evolutionary history such that any later similarities, which is often overblown and non-factual, would be evidence for convergent development not common ancestry.

Otherwise, the earlier stages should be more similar, not less so.

Now evos can shout this is akin to being a Holocaust denier but it's actually just data-driven analysis, something evos ought to try sometimes.

 

[A'isha]

Ok, so you claim the hourglass model aka the phylotypic stage is correct.

How do you account for the fact it is evidence against evo theory, not for it?

You're the only one who thinks it's evidence against "evo theory," based on your total misconception of both what it should "predict" and how geneticists discover evidence of parallel evolution vs. inherited characteristics (and despite your claims, there's plenty of evidence that the hourglass model is correct, though it's still not fully proven to the satisfaction of some scientists).

The "hourglass theory" is actually just one of a number of theories of the evolution of development, with things like adaptive penetration and early conservation also discussed as models to explain embryological development (though so far hourglass seems to be pulling ahead as more studies are done).

 

[randman]

So your false claim that I am the only one is the basis of your argument? You don't even try to answer the details and data analysis I put forward. You just make a personal attack.

Why is that?

Is it because you are incapable of following the reasoning or what?

I'd think someone truly interested in science would enjoy thinking about a challenge and considering it. Someone not truly interested would ignore the data and attack the messenger.

It's fairly clear which camp you are in. Why not switch over to a more scientific approach?

The simple reality is the hourglass model does not work well with common ancestry as the answer because of the wider range of differences earlier on. In other words, the divergence in development had already occurred so any convergence later on would have to be convergent development, not vestiges of common ancestry and so more evidence for design than descent.

 

[A'isha]

In other words, you honestly believe that scientists determine what's the result of common ancestry and what's the result of parallel evolution based not on evidence, but on dogma.

Oh, and you somehow simultaneously believe that there is both no evidence for the phylotypic stage and that the existence of the phylotypic stage is problematic for the theory of common descent. Which raises the question of why you think evolutionary scientists are trying so hard to prove a model that will (according to you) disprove evolution as a whole.

 

[randman]

Are you even going to try to deal with the data driven analysis I gave you showing how the hourglass model would not be evidence for common ancestry?

Or are you going to keep dodging the issue?

 

[A'isha]

What "data driven analysis"? All you posted was a mix of your personal incredulity and your utter misunderstanding of not just how geneticists determine what's inherited and what's parallel evolution, but also your total misunderstanding of how the hourglass model fits into the overall evolutionary theory.

 

[randman]

So you aren't even going to try, eh?

How is it that there would be such wide differences early in development if common ancestry explains some similarities later in development?

Didn't the divergence early in development, according to evos, indicate an evolutionary break?

Just look at the facts. The developmental process is basically a linear progression from one stage to another. The divergence early in development indicates a major evolutionary break early in development, right?

Think about that for a little and get back to me with your explanation.

 

[randman]

Here's a little help for you ANT. Since you will undoubtedly refuse to deal with any analysis you fear hurts your case unless evos acknowledge it elsewhere and even then, you may still avoid it, here is an example of one of the researchers you cited mentioning the same data driven analysis I came up with, but you chose to pretend has no merit, etc, etc,....

To resolve this so-called ‘evo-devo’ debate, Irie and Kuratani analyzed changes in expression levels of thousands of evolutionarily conserved genes at different developmental points in the mouse, chicken, frog and zebrafish. The data provided striking support for the hourglass model, with gene transcription levels most similar at the intermediate stage known as ‘pharyngula’, where the animal has developed primitive precursors of the heart, kidney, brain and other tissues. They observed particularly strong conservation of activity among the Hox genes, which contribute to limb development, as well as several growth factor genes.
These findings offer new fuel for the evo-devo debate, but also raise complicated questions. “It is puzzling for me how vertebrate embryos established differences in early developmental stages while conserving the mid-embryonic stages,” says Irie. “It’s obvious that later developmental stages will not exist if earlier stages fail to develop successfully.”

http://www.physorg.com/news/2011-06-evolutions-waistline.html

Posting this may yet produce an emotional backlash from you, however, as if you accept the researcher's stated problem here, which is the same thing I mentioned, you would have to admit I actually knew what I was talking about and your railing against me was unfounded and just flat out unconscionable.

But on the other hand, if you do not admit the problem exists, everyone can see you are ignoring the scientists you trumpeted that agree with me on the point that they have a hard time explaining divergence within the earlier stages.

It will be interesting to see how you respond.

Will you apologize for falsely claiming I knew nothing, etc,.....? And so man up so to speak?

Or continue to dodge?