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Member (Idle past 2725 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined: |
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Author | Topic: Explanations for the Cambrian Explosion | |||||||||||||||||||||||||||||
mark24 Member (Idle past 5222 days) Posts: 3857 From: UK Joined: |
Doubting Too,
And why is skeletonised invertebrates (note non-skeletonised ones were excluded) & not modern animal appearing in the Cambrian over the period of "about 10 million years" indicative of an intelligent designer? Mark There are 10 kinds of people in this world; those that understand binary, & those that don't
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Blue Jay Member (Idle past 2725 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined: |
Hi, Doubting Too.
Thanks for you comments. I think everyone else has done a good job explaining the common ancestor bit, so I'll refrain from adding my input. But, I'd like to address one thing you said:
DT writes: 2) why not common parts as evidence of a common designer--e.g. a Civic having common parts as Accord is evidence of common designer, HOnda? ( Of course, the draw back is the identity of the designer again... and that is admitted. But, why not designed by an unknown designer? ) The main drawback isn't the identity of the Designer. The main drawback is that the natural world simply doesn't look like a bunch of models built from the same pool of parts, as your Honda cars do. See, Honda has a certain suite of parts that it has available to it, either by its own manufacture or by contract with other companies, and their engineers can pretty much mix-and-match and redesign any of the various parts to make a car. In nature, we don't see that. Typically, what we see is that the parts are not randomly distibuted, but dispensed in regular blocks that form a nested, hierarchical pattern. For instance, there is a group of organisms that contains a set of parts: a protein exoskeleton, jointed legs and a segmented body (we call them the arthropods). A subset of that group has the first three pairs of legs modified into mouthparts, three pairs of legs modified for walking, and a special organ in the antennae (we call them the insects). A subset of that group has two pairs of wings and a specific hingeing of the mouthparts (we call them the Pterygota). The point is that all organisms can be united in a nested sequence like this. The parts are distributed within well-defined groups of organisms. Those groups can be combined with other well-defined groups into a larger, well-defined groups that are united by parts and features common to them all. And, so on, until you can include all organisms within a single group based on shared characteristics. Try this website (the Tree of Life Web Project): they have the phylogenetic tree laid out rather well. You can see how the parts aren't randomly scattered across organisms, as the parts of cars are, but are contained within well-defined, nested groups. ----- How does this relate to the Cambrian Explosion? Well, lots of paleontologists have reconstructed lots of organisms from fossils found in, before and after the Cambrian. The basic features that define most of our modern groups of animals today are found in primitive form, in some of those organisms from the Cambrian Era. Take Pikaia, for instance. It is an animal that resembles simple vertebrates (lancelets). It has a notocord (spinal cord), and muscle blocks very similar to the muscle blocks in lancelets and fish. It doesn't have a skeleton yet, but animals with skeletons are found later. -Bluejay Darwin loves you.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3 |
1) why not common ancestorS as in PLURAL? Because that assumes a completely unneeded other explaination. It's like saying well, I'm sure the car drove from Leeds to here, but I think it flew from Glasgow to Leeds.
2) why not common parts as evidence of a common designer Because that describes nothing like what we observe. The designed objects we can observe do not look like the natural organisms we observe, and they certainly don't form heirachies in the same way. In particular, a designed object will tend not to use multiple different solutions to a problem (unless it has multiple designers), yet every cell in your body uses two different forms of DNA encoding.
3) Why not just Stop this conclusion: 'in our investigation of the fossil we found animals, plants, etc of having ALMOST similar parts?' Because it's not true; there are enough similarities between all forms of life to conclude that they all share a common ancestor. And because it's a deeply unsatisfying conclusion. Especially when the extrapolation is so obvious.
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RAZD Member (Idle past 1432 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hey Doubting Too,
Let's see if I can add to the confusion:
1) why not common ancestorS as in PLURAL? Technically singular is incorrect. What is correct is a common ancestral population, where the population, generation by generation, evolves. Isolated sub-populations can evolve in different ways and over time become reproductively incompatible: speciation. Here we now have two "daughter" populations that are related to a common ancestor population, with many of the hereditary traits of the common ancestor population ... but not all the hereditary traits from the common ancestor population are necessarily (or even likely) shared by either daughter population, and they each have different new hereditary traits. It is just convenient to talk about a common point of ancestry as a "common ancestor" rather than necessarily a factual single individual. You can have a population of organisms in an ecosystem that supports 100 individuals, and each generation those individuals mate, reproduce and die in various quantities such that there are still 100 individuals per generation. After several generations the hereditary traits will all be mixed together without necessarily coming directly from any single individual. They come from the pool of hereditary traits in the population as a whole (which of course is where selection comes in). One should never think of branches as being individuals, but populations, and each branch is in constant flux along it's length with new members added (reproduction) and old members dying (no longer contributing actively to the gene pool). Thus each branching point has a common pool of hereditary traits, where some contribute to one branch and some contribute to the other. COnfUsEd yet? Now back to the Cambrian "million-year-explosion" with a number of already diverse common ancestor populations and the new ability to grow calcium parts from sea-water ... Enjoy. Edited by RAZD, : topic by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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NosyNed Member Posts: 9004 From: Canada Joined: |
1) why not common ancestorS as in PLURAL? In fact, Darwin, in the "Origin of Species" suggested one or several forms as a starting point. He had no reason to know if we are descended from one or from more than one population (thanks to RAZD's note). Since then we have learned a lot (a astronomical understatement) about living forms on Earth. So far all that information says that they are all tied together in a way which suggests that, however many got started, only one lineage has survived through to today. There is a possibility that we are overlooking something somewhere that is a descendant of another lineage but we have no evidence for that.
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NOT JULIUS Member (Idle past 4502 days) Posts: 219 From: Rome Joined: |
Hi Blue,
you writes: Try this website (the Tree of Life Web Project): they have the phylogenetic tree laid out rather well. You can see how the parts aren't randomly scattered across organisms, as the parts of cars are, but are contained within well-defined, nested groups. Thanks, for the link. But, I observed that this "tree" is just an interpretation--an illustration (?). I dug further into the link. Tree of Life Turns Out to Have Complex Roots. That portion of article says, The longstanding road map for finding the universal ancestor, however, turns out in the light of new data to have given misleading directions, and the road map's chief author, Dr. Carl Woese of the University of Illinois, is proposing a new theory about the earliest life forms. Another says...
Life seems to have popped up on earth with surprising rapidity. The planet is generally thought to have become habitable only some 3.85 billion years ago, after the oceans stopped boiling off from titanic asteroid impacts. Yet by 3.5 billion years ago, according to the earliest fossil records, living cells were flourishing, and there are indirect signs of life even earlier, in rocks that are 3.8 billion years old. "There's the gee-whiz point of view, how can life possibly have evolved in 300 million years, which I think is still a problem," said Doolittle of Halifax. But life arriving from outer space is a hypothesis, he said, that "leaves you stunned -- there is nothing more you can say after that." To my untrained mind, these scientists are in effect saying they are as confused as before. (I find comfort in the fact that I am not the only one confused. ) But, they won't stop speculating until.... WHEN? WHEN is the big question? Am I right?
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NOT JULIUS Member (Idle past 4502 days) Posts: 219 From: Rome Joined: |
The confusion continues...
Razd writes: Technically, singular is incorrect. What is correct is a common ancestral population... NosyEd writes: So far all that information says that they are all tied together in a way which suggests that, however many got started, only one lineage has survived Now, you guys really got me confused!! My latest message also confirms that its not only me who is confused--even scientists. Refer to Message 21 the link provided by BlueJay...when explored further. If the Cambrian period indicates appearance of complex things --as if by explosion--then that doesn't prove "common ancestry". It is proof to the contrary--that life "exploded" and that supports.... what ? Edited by Doubting Too, : No reason given.
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Blue Jay Member (Idle past 2725 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined: |
Hi, Doubting Too.
DT writes: To my untrained mind, these scientists are in effect saying they are as confused as before. (I find comfort in the fact that I am not the only one confused. ) But, they won't stop speculating until.... WHEN? WHEN is the big question? Am I right? No, you're still wrong. One thing you need to do is to stop using political debate tactics. Words like "speculate" are only used to slander your opponent's position. You did not notice what all that "speculating" those scientists are doing is based on, but only took hold of the part where it said, "we're not 100% positive that we're correct." I'm not even going to try to explain to you the science of phylogenetics, because it would take entirely too long, and this whole "Tree of Life" discussion is not the point of this thread, anyway. Seriously, though, if you want to debate on this issue, make sure you read a good deal of stuff, and take a class or something, before you come out with a strong position and insist that all scientists are blundering idiots.
DT writes: quote:-New York Times article This is a newspaper article. People who write newspaper articles are trained in the arts of "spicing things up" to make them interesting. You really shouldn't read much into this. The Tree of Life is a fascinating topic, one that perhaps deserves a number of threads of its own to discuss. I provided you the link so you could understand what the tree of life implies: I never intended it to be a continuation of this discussion. If you want to start a thread about the base of the tree of life, go for it. -----
DT writes: My latest message also confirms that its not only me who is confused--even scientists. Two points to be made:
----- Now, back to the Cambrian Explosion:
DT writes: If the Cambrian period indicates appearance of complex things --as if by explosion--then that doesn't prove "common ancestry". It is proof to the contrary--that life "exploded" and that supports.... what ? The "Cambrian Explosion" is an unfortunate name from the phenomenon. Just like the "Big Bang" isn't a theory about the universe "exploding" into existence from nothing, the "Cambrian Explosion" is not an example of biodiversity "exploding" out of nothing. The problem is that the evidence we have is sketchy: only a few locations on earth are known to have accessible Cambrian rocks that have fossils in them. Since each of these locations necessarily has a short date range, it looks like life suddenly appeared, because no life was found in rocks slightly older. This is what I called the "Snapshot Effect" in the Opening Post. More fossil locations and fossil analyses have become available recently, and there is no longer any reason to think that all these animals suddenly "popped" out of nowhere. For that reason, the "Cambrian Explosion" does not appear to be anything particularly unusual that needs special attention from the Theory of Evolution. -Bluejay Darwin loves you.
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Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
Carl Woese's arguments have nothing to do with the Cambrian 'explosion'. The origin of the Eukaryotes and other kingdoms is well before the origin of the metazoa. There was a previous thread on Woese's hypothesis at Woese's progenote hypothesis.
TTFN, WK Edited by Wounded King, : No reason given.
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NOT JULIUS Member (Idle past 4502 days) Posts: 219 From: Rome Joined: |
bluej writes: The "Cambrian Explosion" is an unfortunate name from the phenomenon. Just like the "Big Bang" isn't a theory about the universe "exploding" into existence from nothing, the "Cambrian Explosion" is not an example of biodiversity "exploding" out of nothing.The problem is that the evidence we have is sketchy: only a few locations on earth are known to have accessible Cambrian rocks that have fossils in them. Since each of these locations necessarily has a short date range, it looks like life suddenly appeared, because no life was found in rocks slightly older. This is what I called the "Snapshot Effect" in the Opening Post I think this link could be helpful. Cambrian Fossils First, of all I respectfully invite IDs / Creationists/ etc to take a look at these pictures. They say a thousand words. Forget the "conjectures", "estimates"--made by scientists in this site which obviously espouses evolution. Guys, specially creationists who are more knowlegeable than me, please help. (I thought I was among friends here. It's turning out I'll be skewered dead ! I have questions in my mind--before I'm impaled to death-- when I see these pictures: 1. Blue J accused me.
Blue J writes: One thing you need to do is to stop using political debate tactics. Words like "speculate" are only used to slander your opponent's position. First, I don't see any opponents. I only see friends trying to discuss. But, be that as it may, am I not allowed to use the word "speculate" while scientists may make "conjectures" and "estimates"--words found in this site if you drill down further? 2. Will not anybody have the right to interpret these data opposite what these men of science do? For example, a creationist may say: 'hey these pictures prove that account in Genesis--"let blah...blah bring forth creeping souls/ creatures"? Are these not also fair interpretation of these data? 3. Looking at these 16+ picture, and relating it to the so called "tree of life" which of these do you think is Blue Jay's "ancestor"--if it could be traced ( just an example, Blue )? Could it really be traced beyond reasonable doubt? What convincing evidence will an evolutionist-scientist give me ( I understand there are also creationist-scientists)? Whom should I believe? Note: For those who will answer # 3, please consider the explanations of parasominium about "ancestor"
parasomnium writes: If you trace your ancestry and that of your third cousin twice removed, you will normally find that the both of you share two common ancestors: your great great grandfather and his wife, your great great grandmother. Your third cousin twice removed will call them great great great great grandfather and ditto grandmother - she is twice removed, hence the two extra greats. However, it could be that your great granduncle - your third cousin twice removed's great great great grandfather, but no direct ancestor of yours - is the son of your great great grandfather and his second wife. In that case you share literally only one common ancestor with your third cousin twice removed. Yeah, if I understood it correctly, my third cousins and I may have 1 common ancestor. If we extend that to the case of BlueJ and Me--which common "grand pa" would we have among the 16+ life-forms shown in the above link? 4.What if some of those fosills are found still alive today? Will supporters of evolution abandon their theory? Blue J, could you please answer my question #1, please? Edited by Doubting Too, : No reason given. Edited by Doubting Too, : No reason given. Edited by Doubting Too, : No reason given. Edited by Doubting Too, : Clarity about "ancestor" Edited by Doubting Too, : No reason given.
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bluescat48 Member (Idle past 4217 days) Posts: 2347 From: United States Joined: |
You are confusing yourself by the use of terminology.
Razd writes: Technically, singular is incorrect. What is correct is a common ancestral population.. This is in reference to the fact that it is not just one particular animal of a particular species evolves but that a population of this species undergoes evolutionary changes do to any number of effects of the environment, speciation, separation of the members of the same species etc. The point I made as to why it is a sigle common ancestor is in regards to the evolved species and not a single individual. The other problem is the use of the term "explosion." It was simply used to indicate a large number of new species that evolved during the period, particularly before much the current data was found after the term was coined. Edited by bluescat48, : spelling There is no better love between 2 people than mutual respect for each other WT Young, 2002 Who gave anyone the authority to call me an authority on anything. WT Young, 1969
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NOT JULIUS Member (Idle past 4502 days) Posts: 219 From: Rome Joined: |
bluescat48 writes: It was simply used to indicate a large number of new species that evolved Could we use more neutral words like "came to being" instead of "evolve" and "created"? Just a suggestion, though?
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NOT JULIUS Member (Idle past 4502 days) Posts: 219 From: Rome Joined: |
As I dig deeper into this site--one espousing evolution--my confusion appears to have no end--and may be most scientists.
Trilobita Trilobites
article writes: Darwin was confident in his conjecture that trilobites descended from one Pre-Cambrian crustacean ancestor. But, the trilobite's position in the universal tree of life remains confounded, with debate remaining whether their closest extant cousins are, for example, a crustacean, the horseshoe crab, or among the spiders or scorpions . Classification requires following the tree of life back to points of branching. This we cannot do for the trilobite whose first appearance in the fossil record is in the lower Cambrian. When they appear, they are already diverse in form, and dispersed in geography, clearly indicative of the paucity of the fossil record in the Precambrian, where the roots of trilobite ancestory extend. By the time trilobites appear in the fossil record they are already highly diverse and possess two characteristics that likely served them well to survive in the Paleozoic seas, a well- mineralized exoskeleton, and a highly advanced visual system. Both of these attributes likely resulted from the selective pressures of the ageless evolutionary war between predator and prey, an arms race in which trilobites were surely bold participants. Despite setbacks during numerous Paleozoic extinction events, the trilobite lineage persisted for some 300 million years before finally becoming extinct at the end of the Permian Period. So, Darwin is making speculation. Scientists aren't sure of the "cousins"...Tribulite lineage persisted some 300 million years.. Question:1. If Darwin can conjecture that the tribolite descended from one-precambrian ancestor, and if there is found today a living tribolite almost exactly the same as in the fossil--can I speculate that Darwin took us for a ride?
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Asgara Member (Idle past 2330 days) Posts: 1783 From: Wisconsin, USA Joined: |
Can you explain to me why you think that finding a, once thought of extinct, species alive today would mean anything over all to the TOE?
If you found out today that one of your great-great-great grandmothers was still alive would that mean that you weren't descended from her?
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mark24 Member (Idle past 5222 days) Posts: 3857 From: UK Joined: |
Doubting Too,
Message 16 please. Mark There are 10 kinds of people in this world; those that understand binary, & those that don't
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