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Author Topic:   Icons of Evolution
Huntard
Member (Idle past 2296 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 1 of 65 (481094)
09-09-2008 10:42 AM


In the thread Evidence for Intelligent Design-is there any? Beretta wrote in his opening post:
-the continually rehashed icons of evolution that despite being a collection of old worn, some fraudulent, others thoroughly discredited, most out of date somehow never seem to change. One would think with all the vast network of science, something more convincing would come along, but no.
I wrote further down the thread I would be interested in discussing this topic in a different thread, since it would be off-topic in that one. Beretta agreed, and so this is my opening post.
I'm am currently 26 years old, so not too long ago, I went to highschool, where I of course got taught Bioligy among others. I never heard of these so called Icons of evolution before, in fact the first time I heard of them was when I watched a creationist video. Never before that had I heard of Piltdown man, Nebraska man, Archeoraptor, or any of the others mentioned. So, it seems these "icons" aren't being constantly rehashed. Or was my school just so much better?
I don't think discussing all of the icons at the same time is going to give a good topic, so I would suggest picking one or two and then discuss them here, we could always get more in later. So Beretta, or anyone else, if youre up for it, please pick one or two of these "icons" and let's discuss them.
Edited by Huntard, : Clicked submit instead of preview button

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AdminNosy
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Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 2 of 65 (481096)
09-09-2008 10:57 AM


Thread moved here from the Proposed New Topics forum.

  
Coyote
Member (Idle past 2107 days)
Posts: 6117
Joined: 01-12-2008


Message 3 of 65 (481098)
09-09-2008 11:13 AM
Reply to: Message 1 by Huntard
09-09-2008 10:42 AM


Creationists' icons
I never heard of these so called Icons of evolution before, in fact the first time I heard of them was when I watched a creationist video. Never before that had I heard of Piltdown man, Nebraska man, Archeoraptor, or any of the others mentioned. So, it seems these "icons" aren't being constantly rehashed.
The "icons" are being constantly rehashed -- by creationists.
While we are waiting for the creationists to show up and tell us how science operates, and what it should do, here are some good links on the "icons" for background information:
Piltdown Man
Nebraska Man
Archeoraptor

Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

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gluadys
Member (Idle past 4963 days)
Posts: 57
From: Canada
Joined: 08-22-2008


Message 4 of 65 (481141)
09-09-2008 4:13 PM
Reply to: Message 1 by Huntard
09-09-2008 10:42 AM


The real icons
Actually, the term "Icons of Evolution" was used as a book title by Jonathan Wells and usually refers to the icons he named. None of these are hoaxes or mere media hype like Nebraska man. They are actual cases found in many textbooks and you have probably heard of at least some of them (see list below). Wells contends that these have become iconic models of evolution but that there are problems with all of them.
Here is his list (taken from the Table of Contents of Icons of Evolution):
The Miller-Urey Experiment
Darwin's Tree of Life
Homology in Vertebrate Limbs
Haekel's Embryos
Archeopteryx: the Missing Link
Peppered Moths
Darwin's Finches
Four-winged Fruit Flies
Fossil Horses and Directed Evolution
From Ape to Man: the Ultimate Myth

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Huntard
Member (Idle past 2296 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 5 of 65 (481238)
09-10-2008 5:13 AM
Reply to: Message 4 by gluadys
09-09-2008 4:13 PM


Re: The real icons
Hmm I see. Some of those were indeed mentioned in my lessons, though I don;t really see what the problems are with these, they seemed supportive of Evolutionary theory. Any idea what these problems are, or a link to somewhere I can read about them? Don;t have access to the book. Thanks in advance.

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Replies to this message:
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 Message 9 by gluadys, posted 09-10-2008 8:37 AM Huntard has replied
 Message 11 by Beretta, posted 09-10-2008 10:50 AM Huntard has replied

  
Dr Jack
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Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 6 of 65 (481247)
09-10-2008 6:43 AM
Reply to: Message 5 by Huntard
09-10-2008 5:13 AM


Re: The real icons
That's because there aren't really any problems. Icons of Evolutions, like the rest of Creationist literature, lies somewhere between misunderstanding and inaccuracy, and outright dishonesty.

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Huntard
Member (Idle past 2296 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 7 of 65 (481260)
09-10-2008 8:15 AM
Reply to: Message 6 by Dr Jack
09-10-2008 6:43 AM


Re: The real icons
Alright, I'd still like to read up a bit on this myself, so I can arm myself against this, any idea where this could be done. It seems the talkorigins website Coyote refered to is very helpful here, thanks for that.

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PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 8 of 65 (481264)
09-10-2008 8:36 AM
Reply to: Message 7 by Huntard
09-10-2008 8:15 AM


Re: The real icons
You might find this page at theNCSE, and it's links a useful resource.
I'd also recommend getting a recent textbook - preferably degree-level, not the High School texts Wells focusses on (a very odd choice if he wanted to seriously deal with the evidence for evolution).
I found Mark Ridley's Evolution to be quite good, although I'm neither expert enough nor familiar enough with the competition for my opinion to carry much weight - although the fact that I found it to be accessible despite having little formal eduication in biology must count as a point in its favour (I have the 2nd edition, but the 3rd has some significant new material and probably should be preferred). Mayr's What Evolution Is is cheaper but less detailed (because it's much shorter) and not the best choice for dealing with the issues Wells raises as a result.

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gluadys
Member (Idle past 4963 days)
Posts: 57
From: Canada
Joined: 08-22-2008


Message 9 of 65 (481265)
09-10-2008 8:37 AM
Reply to: Message 5 by Huntard
09-10-2008 5:13 AM


Re: The real icons
Well's point is that this is exactly the problem: they seem supportive of evolution. In fact, they are so supportive of evolution that they are found in virtually all basic texts on evolution. That's why he tries to find a way to undermine them.
But as Mr. Jack says, there are no real problems with them. Probably the only major effect has been to retire the pictures of Haekel's embryos. While they are not nearly as misleading as creationists imply, it is true that Haekel enhanced his portrayal of some embryos to make the similarities more obvious.
His drawings continued to be used because in general they are very good and because they are in the public domain so they are inexpensive for publishers to use. However, the same point can and is made with actual pictures of embryos and that is the way new textbooks are going.
In two other cases the "problem" with the icons is not the actual evidence but an image of it. You have no doubt seen the picture of horse evolution: a reproduction of a mural at (I think) the Smithsonian going from Eohippus to the modern horse. That image implies a straight-line evolution that is inconsistent with the complexity of the actual history of evolutionary development in the Equidae. No biologist would disagree that it is an oversimplified image. But what does that have to do with the actual evidence?
Then the big brouhahah on the peppered moths is that the photos illustrating the camouflaging effects of colour on polluted and non-polluted trees were staged and the photographer made the great mistake of taping moths to the trunk of the tree instead of up in the branches which is the preferred resting place of the moths. As if either of these "mistakes" interfered with the main point. The camouflaging effect of the colour acts as an instrument of natural selection.
The other "problems" are of the same caliber.
There is plenty of discussion of Well's icons on line. I believe talkorigins has a whole article that discusses them all from a scientific perspective. For a creationist perspective just go to Answers in Genesis and do a search on a key word such as Urey-Miller experiment.
Edited by gluadys, : Added last paragraph.

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Huntard
Member (Idle past 2296 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 10 of 65 (481288)
09-10-2008 10:43 AM
Reply to: Message 9 by gluadys
09-10-2008 8:37 AM


Re: The real icons
Ok, after reading up on this stuff a bit, I must say I'm a bit dissapointed. I thought there were some actual problems with these things, but everything I read points to misrepresentation of the facts. Ah well, I'll await an ID proponents view on the matter and then comment further.

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Beretta
Member (Idle past 5598 days)
Posts: 422
From: South Africa
Joined: 10-29-2007


Message 11 of 65 (481290)
09-10-2008 10:50 AM
Reply to: Message 5 by Huntard
09-10-2008 5:13 AM


Urey Miller
Hi Huntard, thanks for starting the thread, just found it now or I would have reacted sooner.
You're right that there are too many to discuss them all at once so how's about we start with the Urey Miller experiment.
In this icon which is still generally mentioned in bio texts, a simulated hydrogen rich atmosphere of methane, ammonia and water vapour was used and a few amino acids were produced along with other substances completely toxic to life.The amino acids that can be produced in this kind of experiment tend to be left and right handed in more or less equal quantities but living things only use left handed amino-acids. There would be nothing to stop the right handed ones from linking up with the left handed ones so no life there.
It was later found by geochemists that the mixture used was not what was indicated to be available in the early rocks so new experiments were done for a more realistic simulation. No amino acids were formed under these conditions.
The problem with this 'icon' is that despite the fact that it is now generally agreed that oxygen was present in the early atmosphere and that would be toxic to organic synthesis even if the amino acids could have formed spontaneously.
I think the point of the criticism of this icon is that it is presented still as a breakthrough experiment for the origin of life and the downside of subsequent experiments is not mentioned which is not honest.
The story line goes that amino acids were produced in these early experiments and amino acids join to form proteins (as if that is what would have happened) and proteins are the main building blocks of living organisms.Since the downside is that realistic simulations produced no amino acids, either the downside of the later experiments should be fairly mentioned or it should be taken out of the books.
It is this kind of thing that intelligent design proponents and creationists want mentioned in the classroom so that a false positive is not taken as fact by people who do not know the follow up.It gives the impression that the random fortuitous generation of life from non-living chemicals is really more than just a vague possibility. Of course the people that support these kinds of presentations do not want the downside mentioned because they have no doubt whatsoever that life began somehow like that with no intelligent input and doubters are not welcome at the party.

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Replies to this message:
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onifre
Member (Idle past 2951 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 12 of 65 (481320)
09-10-2008 1:15 PM
Reply to: Message 11 by Beretta
09-10-2008 10:50 AM


Re: Urey Miller
The problem with this 'icon' is that despite the fact that it is now generally agreed that oxygen was present in the early atmosphere
Im sorry but you'll have to provide evidence for early Earth having oxygen.
However, heres evidence for the complete opposite of that from Columbia U.,
Page not found | Department of Earth and Environmental Sciences
Here's another,
The atmosphere - origin and structure
Here's a quote from it,
quote:
First Atmosphere:
Composition - Probably H2, He
These gases are relatively rare on Earth compared to other places in the universe and were probably lost to space early in Earth's history because
Earth's gravity is not strong enough to hold lighter gases
Earth still did not have a differentiated core (solid inner/liquid outer core) which creates Earth's magnetic field (magnetosphere = Van Allen Belt) which deflects solar winds.
Once the core differentiated the heavier gases could be retained
----------------------------------------------------------------------
Second Atmosphere:
Produced by volcanic out gassing.
Gases produced were probably similar to those created by modern volcanoes (H2O, CO2, SO2, CO, S2, Cl2, N2, H2) and NH3 (ammonia) and CH4 (methane)
No free O2 at this time (not found in volcanic gases).
Ocean Formation - As the Earth cooled, H2O produced by out gassing could exist as liquid in the Early Archean, allowing oceans to form.
Evidence - pillow basalts, deep marine seds in greenstone belts.
Addition of O2 to the Atmosphere
Today, the atmosphere is ~21% free oxygen. How did oxygen reach these levels in the atmosphere? Revisit the oxygen cycle:
----------------------------------------------------------------------
Oxygen Production:
Photochemical dissociation - breakup of water molecules by ultraviolet
Produced O2 levels approx. 1-2% current levels
At these levels O3 (Ozone) can form to shield Earth surface from UV
Photosynthesis - CO2 + H2O + sunlight = organic compounds + O2 - produced by cyanobacteria, and eventually higher plants - supplied the rest of O2 to atmosphere. Thus plant populations
----------------------------------------------------------------------
Oxygen Consumers:
Chemical Weathering - through oxidation of surface materials (early consumer)
Animal Respiration (much later)
Burning of Fossil Fuels (much, much later)
Throughout the Archean there was little to no free oxygen in the atmosphere (<1% of presence levels). What little was produced by cyanobacteria, was probably consumed by the weathering process. Once rocks at the surface were sufficiently oxidized, more oxygen could remain free in the atmosphere.
During the Proterozoic the amount of free O2 in the atmosphere rose from 1 - 10 %. Most of this was released by cyanobacteria, which increase in abundance in the fossil record 2.3 Ga. Present levels of O2 were probably not achieved until ~400 Ma.
----------------------------------------------------------------------
Evidence from the Rock Record:
Iron (Fe) i s extremely reactive with oxygen. If we look at the oxidation state of Fe in the rock record, we can infer a great deal about atmospheric evolution.
Archean - Find occurrence of minerals that only form in non-oxidizing environments in Archean sediments: Pyrite (Fools gold; FeS2), Uraninite (UO2). These minerals are easily dissolved out of rocks under present atmospheric conditions.
Banded Iron Formation (BIF) - Deep water deposits in which layers of iron-rich minerals alternate with iron-poor layers, primarily chert. Iron minerals include iron oxide, iron carbonate, iron silicate, iron sulfide. BIF's are a major source of iron ore, b/c they contain magnetite (Fe3O4) which has a higher iron-to-oxygen ratio than hematite. These are common in rocks 2.0 - 2.8 B.y. old, but do not form today.
Red beds (continental siliciclastic deposits) are never found in rocks older than 2.3 B. y., but are common during Phanerozoic time. Red beds are red because of the highly oxidized mineral hematite (Fe2O3), that probably forms secondarily by oxidation of other Fe minerals that have accumulated in the sediment.
Conclusion - amount of O2 in the atmosphere has increased with time.
*Can you provide evidence against any of this to prove that oxygen was present?

"All great truths begin as blasphemies"
"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks
"I never knew there was another option other than to question everything"--Noam Chomsky

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Chiroptera
Inactive Member


Message 13 of 65 (481331)
09-10-2008 2:06 PM
Reply to: Message 11 by Beretta
09-10-2008 10:50 AM


Re: Urey Miller
Here is some information on the Urey-Miller experiment written explicitly as a reply to Icons.
You're right that there are too many to discuss them all at once so how's about we start with the Urey Miller experiment.
First of all, you have to understand the purpose of the experiment. The purpose of the experiment was to determine whether or not relatively complex organic compounds could form under relatively simple conditions, focusing on the conditions that existed early in Earth's history. One argument against abiogenesis was that complex organic molecules can't form under natural conditions; they can only be formed by already existing life, or under artificial conditions. So the Urey-Miller experiment was meant to see what conditions the formation of organic molecules requires.
And the Urey-Miller experiment was a great success! Under very simple conditions, complex organic molecules like amino acids could form.
-
It was later found by geochemists that the mixture used was not what was indicated to be available in the early rocks so new experiments were done for a more realistic simulation. No amino acids were formed under these conditions.
This is false. The experiment was replicated under a wide variety of different conditions reflecting possible conditions of the early Earth, and in each of them amino acids and other organic molecules formed. In some cases the amounts produced were less than in the Urey-Miller experiment, but they were there.
-
The problem with this 'icon' is that despite the fact that it is now generally agreed that oxygen was present in the early atmosphere....
This in not generally agreed to at all. At least it wasn't present in amounts that would have a significant effect on the early organic chemistry. The presence or absence of oxygen would be indicated by the chemical traces in early sediments; the evidence that there was no oxygen is overwhelming and clear.

Speaking personally, I find few things more awesome than contemplating this vast and majestic process of evolution, the ebb and flow of successive biotas through geological time. Creationists and others who cannot for ideological or religious reasons accept the fact of evolution miss out a great deal, and are left with a claustrophobic little universe in which nothing happens and nothing changes.
-- M. Alan Kazlev

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Dr Adequate
Member (Idle past 285 days)
Posts: 16113
Joined: 07-20-2006


Message 14 of 65 (481341)
09-10-2008 2:22 PM
Reply to: Message 13 by Chiroptera
09-10-2008 2:06 PM


Re: Urey Miller
This is false. The experiment was replicated under a wide variety of different conditions reflecting possible conditions of the early Earth, and in each of them amino acids and other organic molecules formed. In some cases the amounts produced were less than in the Urey-Miller experiment, but they were there.
Does anyone have a list?
Thanks.

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Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 15 of 65 (481345)
09-10-2008 2:33 PM
Reply to: Message 13 by Chiroptera
09-10-2008 2:06 PM


Re: Urey Miller
This is false. The experiment was replicated under a wide variety of different conditions reflecting possible conditions of the early Earth, and in each of them amino acids and other organic molecules formed. In some cases the amounts produced were less than in the Urey-Miller experiment, but they were there.
This is not entirely true, when Miller repeated the experiment in '83 using the combination of gases now believed to be present in the atmosphere of the early Earth he found no evidence of amino acid production. It was only when Bada added iron and carbonate minerals that amino acids were formed. ref

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