Editing the Tape of Evolutionary History Yet Again
| January 8, 2010 | Posted by DonaldM under Biology, Cambrian explosion, Darwinism, Evolution, Evolutionary biology, Natural selection, Science, The Design of Life |
The late Stephen J. Gould once wrote “Replay the tape [of evolution] a million times from a Burgess [the Burgess Shale fossils]beginning, and I doubt that anything like Homo sapiens would ever evolve again. It is, indeed, a wonderful life.” (Gould, Stephen J. [Professor of Zoology and Geology, Harvard University], “Wonderful Life: The Burgess Shale and the Nature of History,” [1989], Penguin: London, 1991, reprint, p.289. Well, maybe we wont’ have to replay the tape, because the tape of evolutionary history is getting replayed all the time, in the sense that lately it seems that every new discovery forces a complete re-write (re-wind?) of evolutionary history. Now we have a recent fossil discovery about to be reported in Nature shows that tetrapods may have crawled out of the seas way earlier than previously thought.
According to the article
A set of fossilized footprints show that the first tetrapods – a term applied to any four-footed animal with a spine – were treading open ground 397 million years ago, well before scientists thought they existed.
An expert unconnected with the research said the find would force experts to reconsider a critical period in evolution when sea-based vertebrates took their first steps toward becoming dinosaurs, mammals and – eventually – human beings.
“It blows the whole story out of the water, so to speak,” said Jenny Clack, a paleontologist at Cambridge University.
The work appears in Thursday’s issue of the journal Nature.
Despite Gould’s fantasy about rewinding tapes, it seems clear we’ve yet to see the first one correctly. In fact, as more and more discoveries like this one are forthcoming, it seems less and less likely that there even is an evolutionary tape to rewind, or if we even have the right tape. It will be interesting to see how this new find gets edited into the evolutionary tape.
UPDATED: Subsequent to posting this, I found this blogpost at Evolution News and Views written by Casey Luskin. Casey makes a good point regarding this new fossil find and its implications for the oft touted evolutionary link Tiktaalik.
44 Responses to Editing the Tape of Evolutionary History Yet Again
Leave a Reply
You must be logged in to post a comment.
Margulis’s hyperbolic statement refers to Neodarwinian Theory, not to Darwinism or to the fact of evolution. She proposed an updated Theory of Evolution, one based on symbiogenesis. Modern evolutionary theory incorporates many of Margulis’s insights. Her findings offer no comfort to Intelligent Design. She’s “definitely a Darwinist.”
Zachriel (#17)
Thanks for your comments. I missed the part where you commented on whether and why tracks seem to precede the relevant animal fossils.
I also missed the part where you disputed my quote of Graham I that “Its not like a steady succesion from one model to the next.” Have you also given up on gradualism?
I agree with you, and with the later Popper, that falsification is not a good dividing point between science and non-science. You seem to miss one implication, which is that one cannot use falsification, or rather the lack thereof, to rule out ID as a scientific theory. (If you wish to see my philosophy of science, you can find it by clicking on my name and reading the first chapter of my book.) One can insist that the earlier Popper is right. But that paints naturalistic evolution as a failed theory, being either falsified, or unfalsifiable, neither of which will fit the earlier Popper’s definition of science.
I personally like Imre Lakatos’ idea of scientific research programs. That is why, using a creationist (not just ID) program, I predicted, looked for, and found carbon-14 in fossil material conventionally dating over 300 million years old. That would seem to put not just ID, but YLC, into the field of science.
I am interested in your take on the Cambrian rabbit. I would maintain that naturalistic evolution is not directly falsifiable because it is not a theory, but a scientific research program. You are free to disagree. I might suggest that before you do, you read the discussion that starts here:
http://www.uncommondescent.com.....ent-311949
Especially comments 189, 198, 206, 210, 212, 234, 255, 257-259, 309-317, 323 (the last comment).
Graham 1 at #9:
No one, and I mean absolutely no one, with a real interest in science and reasoned debate, would ever be caught dead over at Phoolrangula. You may as well have a town hall meeting about public education and invite the crips and the bloods. You would expect, and no doubt get, at least as much intelligent debate in that venue as you will find over at Phyrangula.
Because a given fossil is almost certainly not the first or the last of a lineage. It’s a single data-point.
Perhaps you mean phyletic gradualism. Evolution doesn’t happen at a constant rate.
Falsification is an important, but not flawless heuristic. The idea is to divide the world into two empirical possibilities clearly demarcated by the potential falsification. However, a potentially falsifying observation can be just as prone to theoretical bias as any other observation. And such clear demarcation is not always available.
The anomalous precession of the perihelion of Mercury is a case in point. It could have been due to some other body influencing Mercury’s orbit. So it might have been an unexplained anomaly. Or if it were an actual falsification, we could retain Newton’s Theory by simply excluding Mercury’s precession from its domain until a more satisfactory resolution was found.
Unfortunately, the term “Intelligent Design” is subject to equivocation. It’s more precise to deal with specific claims.
A theory is nearly always a structured collection of interrelated claims. Only specific claims can be directly falsified, though if the falsified claim is fundamental to a theory, then it could mean the theory is scrapped. Aspects of the Theory of Evolution has been falsified many times; consequently, the current Theory of Evolution is not the same as Darwin’s Theory of Evolution.
If a Precambrian rabbit were demonstrated (rather than merely asserted), it would precede any plausible evolutionary ancestor. Time-traveling Leporidae?
The Theory of Evolution is a scientific theory that is comprised of a number of interrelated and falsifiable scientific claims (actually several versions, which though sharing most fundamental claims, yet vie over some details). And yes, the Theory of Evolution is constantly being modified in the light of new data, especially with regards to the historical narrative.
We all believe gravity is a fact (although another thread here makes me suspect that no, we do not all take it for granted) but aside from that, even though most of us take gravity for granted, science is by far finished with it; it is still searching for more info, like gravitons, knowledge about what gravity is, how does if fit into the great framework of the ‘theory of everything’?
Just as a pendant to the frequent complaints about evolutionary theory not being static. Meaning continued research and updating of a theory doesn’t equate to doubts about, falsification or rejection of the basic fact, be it gravity – or evolution.
http://www.pnas.org/content/97/9/4426.full
The Vendian-Cambrian boundary is now placed at ?543 Myr, and the duration (?45 Myr) of the Cambrian is substantially shorter than once thought.
Oops, the ? actually was ASCII F7H, (meaning approx?)
Dear Editors,
Please respond in a normally threaded message. It makes following a conversation easier. Previous administrations here at UD have disavowed editing other people’s comments except to ban them.
As well known as the term “Cambrian Explsion” is, I don’t know of a hard and fast definition of it. Here is one from PBS educational material:
Then, between about 570 and 530 million years ago, another burst of diversification occurred, with the eventual appearance of the lineages of almost all animals living today. This stunning and unique evolutionary flowering is termed the “Cambrian explosion,” taking the name of the geological age in whose early part it occurred. But it was not as rapid as an explosion: the changes seems to have happened in a range of about 30 million years, and some stages took 5 to 10 million years.
I grant you that there are sources that agree with you, such as this paleobiology website:
The theory of the Cambrian Explosion holds that, beginning some 545 million years ago, an explosion of diversity led to the appearance over a relatively short period of 5 million to 10 million years of a huge number of complex, multi-celled organisms.
I agree that we can have differing opinions, but not differing facts. Here, however, we are not dealing with facts, merely popular terms.
In any case, I am heartened that we agree on some of the most basic aspects of the discussion – the reality of deep time, the reliability of dating methods and the geologic column, the ability to understand trace fossils and other fossil remains, and the testimony of all of these to a series of life forms that were related to each other (common descent).
Nakashima (#2, #38) and Cabal (#36-37),
There is a common confusion between the Cambrian and the Cambrian Explosion. This confusion is fostered by sites PBS site cited by Nakashima. If it can be maintained that the Cambrian explosion happened over a long time, it will not appear to be so difficult to explain it as being consistent with Darwinian evolution.
The problem, to state it succinctly, is that there are very few, and so far restricted kinds (phyla) of organisms before the Cambrian, whereas not just at the end of the Cambrian, but at the earlier strata, for example the Chengjiang in China, nearly all the modern phyla are present, and often extinct phyla as well. That time frame thus is not between the late Precambrian and the late Cambrian, but between the late Precambrian and the early Cambrian. Thus 40 to 45 million years is a gross overestimate for the time during which the changes happened. Estimates of 1-10 million years are more appropriate.
It is fascinating to read the Wikipedia article on the Cambrian explosion. Obviously, they also have an interest in minimizing the problem. However they still allow that
The next paragraph is just choice:
Note the desperate attempts to avoid the implications of the problem. The first attempt is to challenge the data, or to deny that the fossil data reflect the biological reality. The difficulty with this approach can be appreciated by noting that some estimates put the divergence of protostomes and deuterostomes at some 896 million years ago, which means that for some 350 million years we have evolution without any known fossil evidence. That makes even 40 million years look like a very short time.
The next attempt is to ask “what might have caused such rapid change”. Well, of course, designers could have but Wikipedia isn’t going there
. Maybe if there is no (unguided) mechanism, the problem will just go away.
The final attempt is to obfuscate the problem. “Interpretation is difficult due to a limited supply of evidence, based mainly on an incomplete fossil record and chemical signatures left in Cambrian rocks.” No it’s not. Interpretation is difficult due precisely to the excellent preservation of the fossil record in the Cambrian If one wishes to argue the incompleteness of the fossil record, one has to make that case for the Precambrian record. This statement makes me wonder what Kool-aid the Wikipedia authors have been drinking.
The lack of logic is again evident in the following quote:
Note the lack of support for the idea that Whittington actually subscribed to punctuated equilibrium. But more importantly, note the suggestion that the theory of puunctuated equilibrium influenced the empiric observation that the fossil record indicates the rapid development of phyla. In reality, of course, it was precisely the reverse. Eldredge and Gould developed their theory to account for the data of the fossil record. They had started out as more or less orthodox Darwinists. It was the fossil data, their area of expertise, that convinced them otherwise.
More of this minimization of the problem continues:
Simply? This kind of argument cannot conceal the fact that if we take the fossil record at face value, it indicates that fundamentally differently types of organisms suddenly appeared in the fossil record. As Dawkins (TBW) put it, “It is as though they were just planted there, without any evolutionary history.” (Read the whole quote; it is fascinating.)
Zachriel,
I’ll get back to you later. I ran out of time, but am pleased by the tone of your response.
Zachriel:
The prediction seems to be falsified by the new find.
Ya see Shubin et al. were looking for a trasitional and found one AFTER the transition was already esyablished.
In order for theior’s to be a good prediction they needed to find the transitional BEFORE tetrapods made it to land.
How would rabbits in the Cambrian falsify the theory of evolution?
You don’t know that.
For all you know there are plausible ancestors that just haven’t been found.
Also you don’t ewven know what a plausible ancestor is because you don’t know what makes a rabbit a rabbit.
I could think of several things that could explain it away and I am sure evos could think of more.
This article is object of another article at Biologos.
http://biologos.org/blog/footprints-in-the-sand/
Zachriel:
The word “evolution” is always equivocated:
Equivocation and Evolution
and
Equivocation and Evolution cont
Zachriel (#34),
Could you explain why this is an answer?
If you had said that there are many more tracks than fossils, and therefore the track distribution would be expected to be outside, and therefore earlier than, the fossil distribution, I might wonder about the premise, but at least understand the argument.
Reading your answer,
It looks like you are proposing the Hopeful Monster theory, at least as far as the fossil record is concerned. Suddenly, or perhaps within a few thousand years, an alga became a trilobite. Is that the explanation of the Cambrian explosion?
When, in answer to my comment,
you reply,
you sidestep the issue rather than meet the thrust of the comment head on. It’s a good debating tactic, but in this case it is not helpful in finding the truth. If falsification is not a defining characteristic of science, than its absence cannot be used to declare a theory, or even a collection of theories, unscientific. That means that specifically it is not legitimate to use it to rule out ID as non-scientific. ID may be non-scientific, but the criterion fails.
Is there any particular reason why we should trust the current version to be more successful than the past ones?
Did you read the discussion at the link I provided? Perhaps you can reply to Cambrian plants (scan down to “In the mid- 1940s”), specifically oaks, and Precambrian angiosperm pollen (see R. M. Stainforth, “Occurrence of Pollen and Spores in the Roraima Formation of Venezuela and British Guiana,” Nature, Vol. 210, No. 5033 (April 16, 1966), pp. 292–294.). I would be interested in your answer.
I suspect that you and I are closer together than it might appear on the nature of scientific theories. It appears that you just are not used to the terminology of Lakatos, where “scientific research program” is used for a core theory which is not directly testable, with surrounding theories and heuristics, with the surrounding theories being testable. The core theory gains or loses credibility based on the ability or lack thereof of the surrounding theories to predict novel facts, and their ability to avoid apparent falsification. Does that seem heretical to you?