Something, Jar, that seems to get forgotten is, other than a couple of creatures, what Cambrian life would look like, to the untrained eye, is a bunch of very small "worms" and "bugs"
Exactly. That was one of the reasons I included the link to the pdf article that refers to some of Chen's own work from just two years after the interview referenced in the OP. IMHO it was importnat to actually see some of the pictures and the descriptions of just what they had to go through to even find some of the critters.
PaulK, if you read what Chen and his Taiwanese associate have to say, they clearly indicate that the prior evo claims that creatures with soft bodies did not fossilize well is wrong. They showed this with the discovery of thousands of fossils, and yet we still see in the process evidence that they say "no evolutionary theory can explain."
Why do they say this? Because of what the fossil record shows. It just does not show evolution producing the phyla as evos predicted, and the excuse for the failed prediction, fossil rarity, doesn't work in this case.
That's why they call it a paleontological mystery.
quote:The dearth of earlier fossils made it impossible to test ideas about what triggered the “explosion” or even to say for sure whether it was real or merely seemed so because earlier animals left few detectable traces of themselves. But research over the past half a dozen years—including ours in Guizhou Province—has changed the long-held view, suggesting that complex animals arose at least 50 million years earlier than the Cambrian explosion.
quote:Yet as Charles Marshall of Harvard University has argued and as our fi ndings support, the genetic tool kit and pattern-forming mechanisms characteristic of bilaterians had likely evolved by the time of the Cambrian explosion. Thus, the “explosion” of animal types was more accurately the exploitation of newly present conditions by animals that had already evolved the genetic tools to take advantage of these novel habitats rather than a fundamental change in the genetic makeup of the animals.
So there we have it, it seems there was no explosion. It looks like it was already evolved organisms suddenly finding themselves in a niche that was to their advantage (by virtue of creating it for themselves) and so they became the dominant life forms. Kind of like a biological feedback effect in a way.
You gotta ask them. But Chen, in his later discoveries HAS provided the evidence that shows evolutionary theory can explain what is seen in the Cambrian. He found evidence for bilaterality going back atleast 50 Million Years earlier than we had seen so far.
How does your message six answer Rand's question as to what you mean? I was wondering what you meant also, since most IDists beleive all life was created within a short timespan and not to be a continuous process.
Randman, you seem to be missing the point. Chen's own findings later falsified the points he was making in your quotes from an earlier year. As the article Jar posted discusses, Bilateria can be found in the fossil record long before the Cambrian - although finding them is a matter of significant technical difficulty, for some of the reasons already discussed.
quote:Ten phosphatized specimens of a small (<180 micrometers) animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, dating from 40 to 55 million years before the Cambrian. Seen in sections, this animal (Vernanimalcula guizhouena gen. et sp. nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilateral, anterior-posterior organization; a ventrally directed anterior mouth with thick walled pharynx; and a triploblastic structure. The structural complexity is that of an adult rather than a larval form. These fossils provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.
If Chen and his associates claim that the lack of fossils is anything other than a problem of the fossil record then the evidence is against them. The discovery of phsophatised organisms from the period preceding the "explosion", which indicate that the diversification had started well before is strong evidence for that.
To explain, phosphatisation is a rare form of fossilisation that is only good for preserving very small organisms. The more usual forms of fossilisation only preserve considerably larger forms. Thus it appears that the early diversification involved organisms too small to be represented in much of the fossil record.
You are also wrong about the production of phyla. By the very nature of taxonomy we should expect to see phyla appearing early. Even Linnean taxonomy was based on modern organisms and if the divisions seen are the product of evolution then the most basic divisions should appear early on. It is not that the animals of the Cambrian explosion were so radically different that they would automatically be classified in different phyla if we made no reference to modern life - it is that the differences between them are important to the classification of modern life.
More importantly you misrepresent Chen in one crucial respect. He claims that currently accepted theories of evolution cannot explain his observations - but HIS theories can. He is not attacking evolution, he is promoting his own views.
How does your message six answer Rand's question as to what you mean?
Can you be more specific about what you don't understand? I thought my message was pretty clear.
I was wondering what you meant also, since most IDists beleive all life was created within a short timespan and not to be a continuous process.
That's my point exactly. Creationism refuses to believe that evolutionary processes can explain more than a fraction of the diversity of life on Earth.
One example of one diversity event for which evolutionary processes may not suffice to explain doesn't substantiate that position. We've still got the vast majority of life on Earth being explained by evolutionary processes, which proves creationism wrong.
Modulous, except these guys in the OP say the fact we found complex or whatever you want to call them creatures earlier, compresses the time period for them to have evolved even further, and with such an excellent fossil record having been found, the fact we don't see the earlier forms transitioning in this manner that:
no evolutionary theory can explain this
Can one of you guys address what Chen and his colleague are saying?
quote:Can one of you guys address what Chen and his colleague are saying?
We have addressed it. His comment
no evolutionary theory can explain this
"Intellectually, scientifically, even artistically, fundamentalism -- biblical literalism -- is a road to nowhere, because it insists on fidelity to revealed truths that are not true." -- Katha Pollitt
Modulous, except these guys in the OP say the fact we found complex or whatever you want to call them creatures earlier, compresses the time period for them to have evolved even further
But work subsequent to the OP falsifies that. They previously thought that the evolution of these organisms started at x years, and the diversity was seen at x + 2 million years. Thus the compression. However, the evolution of these organisms started that at x - 50 million years. So the diversity of life came about not in 2 million years but instead 52 million years. No compression at all.
Can one of you guys address what Chen and his colleague are saying?
Sure. Which piece of work? Their earlier work (from the OP), or the work that that superceded it (brought up by jar)? I've addressed both, so tell me which one you mean, and we'll talk about it.
This message has been edited by Modulous, Sat, 25-February-2006 06:18 PM
That still doesn't explain it, modulous. Maybe you can elaborate. What they say is they were looking for more primitive organisms and instead found more advanced, and finding more advanced earlier, in their view, refutes current evo mechanisms.
So why wouldn't finding even more advanced organisms even earlier just make their point all the more stronger?
Also, did you catch they are making the same point I have been making onthe fossil record. They are saying that the current evo claims of fossil rarity are wrong; that the fossil record is a lot more complete and does show soft body creatures than what previous evo models claimed, and armed with such awareness of what the fossil record shows, they made the bold statements they make. Basically, they are saying the fossil record contradicts current evo models, and so "no evolutionary theory can explain this...."
Now, I am open to any suggestion that later finds have changed their stance, or should have changed their stance....I just have not seen it yet in what you guys have posted....in fact, it seems pretty clear to me that these guys are evolutionists themselves, and are very open to accepting evolutionist mechanisms if that is reasonable. They have just come to the conclusion that evo mechanisms are not reasonable, at least not the ones put forth so far.
At any rate, the Cambrian "explosion" may not have been all that "sudden", and only marks the appearance of hard body parts that fossilize (more) easily compared to the soft-bodied precursors.
Somehow I think the message in the OP and the links are not getting through.
1. Chen's work shows that soft-bodied creatures are extremely well-preserved in the fossil record, thus refuting the common evo explanation you offered.
In fact, the pair had failed to find any recognizable body plans showing steps along the way toward the complex Cambrian animals, with their legs, antennae, eyes and other features. What they had actually proved was that phosphate is fully capable of preserving whatever animals may have lived there in Precambrian times. Because they found sponges and sponge embryos in abundance, researchers are no longer so confident that Precambrian animals were too soft or too small to be preserved.
2. Their finding of PreCambrian phyla millions of years earlier than thought is part of their argument to explain why current mechanisms cannot explain the data, not evidence against their hypothesis here as some on this thread have maintained.
Biologist had been expecting to see something that would like a primitive ancestor to the middle Cambrian animal called Pikaia, formerly promoted as the world's earliest chordate. Rather than finding evidence that Pikaia had a less-complex ancestor, Chen instead found a chordate that already displayed many vertebrate characteristics 15 million years earlier.
This led the biologist publishing with Chen to conclude:
Taiwanese biologist Li was also direct: "No evolution theory can explain these kinds of phenomena."
What I would like to see is some evo here take the time to grasp Chen's and his associates' claims, and then offer a rebuttal. To date, it doesn't appear anyone even "gets" what the Asian scientists are saying.