Fletis Humplebacker wrote:
"John Harshman"
Fletis Humplebacker wrote:
John Harshman wrote:
Fletis Humplebacker wrote:
[snip]
Darwinian evolution predicts gradual change,
true, but the long periods are only with respect to human lifetimes, not
geological eras.
So when the experts in the field say lifeform appearances
are sudden we should discount their words? I think they
are aware of the time frames involved.
We shouldn't discount their words. We should understand what they mean:
sudden in geological terms. Look below at your Gould quote: "in a
geological moment", by which, if you read the whole quote, you will see
that he means a minimum of 5 million years.
That isn't in dispute, his reference is the geological record, not a
stop watch. The point is that it was, by all accounts I've seen so far,
sudden. Hense the term "explosion", which was contrary to the traditional
view of evolution.
Clearly there was something sudden going on, if your definition of
"sudden" includes periods of 5 million years. Exactly what was sudden is
a matter of contention. The traditional view of evolution you refer to
is not necessarily Darwin's, since he said that evolution was probably
not constant in rate but proceeded in bursts interspersed with long
periods of stasis. Again, these bursts could take 100,000 years or more.
Some of this "traditional" view is Gould's strawman, as he needed to
make his theory of PE appear revolutionary. Some of it was due to the
mistaken impression of many paleontologists about what the consequences
of natural selection ought to be in the fossil record, which was
essentially a misunderstanding of time scales. In order to see a gradual
trend, sustained over a million years or more, natural selection by
itself won't do it. Any strength of selection capable of moving a
population's characteristics would operate much too quickly. What you
would need is an environment changing at just the right rate so that the
population optimum, the target of selection, would move smoothly over
that time. Natural selection would just be keeping up. Also, it was only
comparatively recently that the highly episodic nature of deposition was
fully appreciated.
STEPHEN J. GOULD, HARVARD, "The Cambrian Explosion occurred
in a geological moment, and we have reason to think that all major
anatomical designs may have made their evolutionary appearance at
that time. ...not only the phylum Chordata itself, but also all its major
divisions, arose within the Cambrian Explosion. So much for chordate
uniqueness... Contrary to Darwin's expectation that new data would
reveal gradualistic continuity with slow and steady expansion, all major
discoveries of the past century have only heightened the massiveness
and geological abruptness of this formative event..." Nature, Vol.377,
26 10/95, p.682
Gould had an axe to grind. You are right about one thing, that people
tend to interpret data to fit their theories. That's why science is a
social effort and can't depend on one person. Others have shown how
Gould misinterpreted some of what he saw. The Cambrian explosion may
have spawned most phyla, though we can't tell this from the fossil
record,
You know, you are constantly telling me to believe you and not my
lying eyes. You want to discount comments if they are quoted on
creationist sites then argue with them even if they aren't. You believe
that you know more about the fossil records than Gould did, that's fine
with me but don't expect me to come aboard that easily.
I do know more than Gould did at the time he wrote that. There are new
discoveries every day, and ten years can make a lot of difference. But
you are picking out little fragments of Gould that distort his meaning,
and lots of paleontologists disagree with even his real meaning.
And what did I distort? And no one suggested that evolutionists were
harmonious, in fact my point has been just the opposite.
I'm not sure you have a point at all. You are of course not the
distorter; whoever mined the quote did that, and you are just passing on
the misunderstanding.
I have
difficulties with his theory of how things happened but not with his
observations on what did happen. I've seen no evidence that his research
was sloppy.
So you pick what you like and throw away what you don't.
I thought that's what you were doing? I never took issue with what he
found, only his theory of why it was. Those are two separate things.
You have no clear idea what he found, because you have never read
anything he wrote except these little snippets. You have no basis to
accept or reject anything he said.
And Gould
actually did no research on the Cambrian explosion. He wrote a popular
book, and in his early years he did some simulations that bear on the
question, but that's it.
No research?
No research *on the Cambrian explosion*.
That's hard to believe. surely he must have realized
it would be read by his peers. Not that I didn't believe you but I
looked into it and you are downplaying his research and role within
the scientific community.
Not at all. He was an important paleontologist and evolutionary
theorist. But he did no research on the Cambrian explosion.
http://www.arn.org/docs2/news/gouldobituary052702.htmn
Noting that in graduate school Dr. Gould dodged bullets and drug runners
to collect specimens of Cerion and their fossils, Dr. Sally Walker, who studies
Cerion at the University of Georgia, once said, "That guy can drive down the left
side of the road," which is required in the Bahamas, "then jump out the door and
find Cerion when we can't even see it."
Note: Cerion is a genus of land snails. Gould was working with
Quaternary (very recent) fossils here. Nothing to do with the Cambrian.
March, Harvard University Press published what Dr. Gould described as his magnum
opus, "The Structure of Evolutionary Theory." The book, on which he toiled for decades,
lays out his vision for synthesizing Darwin's original ideas and his own major contributions
to macroevolutionary theory.
"It is a heavyweight work," wrote Dr. Mark Ridley, an evolutionary biologist at University
of Oxford in England. And despite sometimes "almost pathological logorrhea" at 1,433
pages, Dr. Ridley went on, "it is still a magnificent summary of a quarter-century of influential
thinking and a major publishing event in evolutionary biology."
Agreed. And irrelevant to the point. The book does cover the Cambrian
explosion. Nobody ever said Gould didn't think and write about the
research that others had done on the subject. But he did none of his own.
[snip]
Usually when you quote someone you quote the relevant material. Disliking
where they came from doesn't make them go away. His quotes are entirely
consistent with what I've read of him and is consistent with his reasoning
for coming up with Punctuated Equalibrium.
I doubt you understand or know his reasoning, since all you have ever
read was these trimmed snippets. Have you ever read any full article,
paper, or book that Gould wrote? I have. Don't all the ellipses make you
just the least bit suspicious?
Preston Cloud & Martin F. Glaessner, "Ever since Darwin, the geologically
abrupt appearance and rapid diversification of early animal life have fascinated
biologist and students of Earth history alike....This interval, plus Early Cambrian,
was the time during which metazoan life diversified into nearly all of the major
phyla and most of the invertebrate classes and orders subsequently known."
Science, Aug.27, 1982
What do you think Cloud and Glaessner meant by "this interval"? They
clearly aren't talking about the Cambrian explosion, because they say
"plus Early Cambrian".
It's clear to me that they are talking about the abrupt timespan of
appearance and diversification of life, which includes the early Cambrian
period.
The Early Cambrian alone is about 25 million years long. Add some other
unspecified period to that and how abrupt is it?
Yes, according to everyone else that I've read. The words Cambrian Explosion
comes to mind.
You are being highly flexible about time here. The Cambrian explosion is
a short period. But Cloud and Glaessner obviously were not talking about
that, but about some unspecified longer period. If you want to encompass
most of the first clear appearances of phyla with good fossil records,
that short period is good enough. If you want to encompass all the
phyla, it's not. If you want to encompass most classes, you need longer
still, and if you want to encompass most orders, you will need to
enlarge that to the entire Paleozoic.
I don't know what they mean, but most classes
don't come along until the Ordovician or later, and most orders not
until the late Paleozoic. Also note that they are talking here about
just those phyla with good fossil records.
That's your belief but that isn't what they said. There's no mention
of fossil record quality, but "all of the major phyla and most of the
invertebrate classes and orders subsequently known."
We don't know what they're talking about because the quote doesn't tell
us.
Yes it does.
"Ever since Darwin, the geologically abrupt appearance and rapid
diversification of early animal life have fascinated biologist and students
of Earth history alike..."
Yes, that's clear up to a point. I'm trying to figure out what "this
period" means, and I can't.
But I do know when, according to the fossil record, most
invertebrate classes and orders arose. And it's not in the Cambrian. I
can't find a single source on the web for this (though there are clues
for individual groups here and there). You might want to check out this
book: M. J. Benton (ed). 1993. The Fossil Record 2. Chapman & Hall, London.
1993? Ten year old stuff is too old but a 12 year old book will do? I'm
not buying into it since it contradicts everything I've read and I don't have the
time or opportunity to excavate fossils for myself.
The reason you think it contradicts what you have read is that you don't
understand what you have read. The creationist sites you frequent do a
good job of obscuring the meanings of the stuff they quote, so not all
the blame belongs to you. And I'm not sure you have any clear idea of
the difference between a phylum and an order anyway.
He
www.encyclopediaofgeology.com/samples/026-2.pdf
This pdf has a diagram showing the stratigraphic ranges of the 26
traditional orders of brachiopods. If you will look, you will see that
13 of them, or just half, originate some time in the Cambrian. Now, the
Cambrian is 53 million years long, and the explosion is just a small
part of that. A couple of those orders originated before the explosion,
and several after it. But never mind, take the whole Cambrian. You will
see that the other half arose at various times through the rest of the
Paleozoic, and one even in the Triassic. And that's about the best case
you're going to get, because most brachiopods became extinct at the end
of the Permian, giving them little opportunity to give rise to new
orders. I don't think you could find another phylum with anywhere near
so large a proportion of ordinal first appearances during the Cambrian.
But this stuff isn't so easy to find on the web, and I was lucky to get
that one.
By the way, you have consistently dodged this question: What is a
phylum, or a class, or an order to you? If you think all species are
separately created, higher taxonomic groups must merely be arbitrary
assemblages of species. Why even talk about them?
[snip]
A fossil fight would be an interesting read but the general consensus is
as that alot happened in a geologically short time span and it defies
the traditional evolution model.
How do you know what the general consensus is? You have never read
anything except what some creationist web sites tell you. You think they
don't have an agenda here?