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Author | Topic: Haeckel in Biology Textbooks | ||||||||||||||||||||||||
Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
Haeckel's other mistake was in fudging his drawings to make it seem that embrylogical development retraced evolutionary history more closely than is actually the case. I do not believe Haeckel did this, in his own words:
quote: (From the preface to the third edition of The Evolution of Man, vol. 1) To the best of my knowledge, there is not a single feature in Haeckel's drawings that is not present in the real embryos. Haeckel's purpose in "fudging" the drawings was, it seems in the context of his work, not to misleadingly emphasise his case but to show the features clearly to those not familiar with looking at biological organisms. And, frankly, I don't find this unreasonable. It's pretty much standard practice when explaining anything to use diagrams that omit extraneous detail to the point you're making, no-one is going to look a this diagram and complain it's "fudged":
yet it is further from reality than Haeckel's drawings.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
I have pulled out the first textbook that I could find. It is new. It has Haeckel's embryos in it. It may not call them Haeckel's embryos but it still clearly shows the earliest stages as being the most similar.Haeckel's fraud lives on. That's because - gasp - they are. Really, if you're going to criticise science textbooks you should bother to learn some science first.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
Am I to understand, then, that you have no actual answer to his reasoning?
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
I'm curious. Do you actually deny that embryos of different species at earliest stages look like each other? Because for one thing they actually are pretty darn similar to each other at the earliest stages. So, are you lying for jesus or just playing dumb? We should be cautious about overstating the similarity of early embryonic stages; while there are significant similarities in embryonic development both at the macroscopic and biochemical levels; the phylotypic stage as presented by Haeckel (and others) is a simplification. ref: Richardson, M.K., Hanken, J., Gooneratne, M.L., Pieau, C., Raynaud. A., Selwood, L. and Wright, G.M. (1997): There is no highly conserved embryonic stage in the vertebrates: implications for current theories of evolution and development. Anatomy and Embryology 196(2): 91-106
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
No, once again, that is not what he was doing. He was fraudulently representing the earliest stages of embryonic development as the most similar and again, this is not true. The midstages are the most similar -so he lied, selected only those cases that supported his case and represented the midstages as the early stages. Can you identify a single labelled feature in Haeckel's drawings that is not present in the real embryos? You throw around terms like 'lie' and 'fraud' with casual abandon, yet the central point that there is not a single feature in Haeckel's drawings not present in real embryos remains.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
I repeat my request of Message 33, please identify a single feature present in Haeckel's drawings that is not present in the real embryos?
(edit) You can find photos (not drawings) of the Carnegie Stages of human embryos here, and of photos of Mice, Chicken, Fish, Amphibians and Sea Urchin embryos in various stages here Edited by Mr Jack, : Provided links Edited by Mr Jack, : No reason given.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
It's exactly the point; the features described by Haeckel do exist, and are most similar in more closely related species. You keep claiming fraud; when there is none. Haeckel's embryos are no more fraudulent than any other diagram.
That's what Haeckel did, giving a completely false and misleading impression to support his favorite theory. Haeckel isn't trying to convince; he's trying to explain. Just as modern textbooks are. The difference being of course, that Haeckel's theory was wrong.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
Looks to me like it illustrates my point well also -put them right next to each other and they are nowhere near as alike as they are depicted in textbooks -one wouldn't be able to get one's point across nearly as effectively with the real thing -I'm sure you'd have to agree that the different types are clearly distinguishable. As they are in the drawings. Of course the features are clearer in the drawings; that's because - gasp - they're drawings. In the photos you have the embryos in different positions and poses, with different stains and in different lighting, you have the differences inherent between any two biological specimens and you have the difficulty of the untrained eye identifying the important features of a real specimen. To be fraudulent, the drawings would have to show features that aren't there - they don't. And this remains the key point.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
Was there any particular criterion for the choices of stages there? If you follow my original link you'll see they're examples from a lesson on teaching people how to extract and prepare embryos for study. It was chosen simply as the best examples I could quickly find on the web of actual embryo photos.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
You've already posted an image clearly showing pharangeal arches (aka gill slits) in humans. Labelled 2 & 3. If you'd gone on to the next carnegie stage you can see the 4th arch.
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