From: Cliff Lundberg <cliff@cab.com>
>Richard Wein wrote:
>
>>I said quite clearly that I was *not* using Darwinism to mean Darwin's
>>understanding of the process of evolution. Since no-one (if they know what
>>they're talking about) understands evolution in that way any more, it
would
>>be pointless to use Darwinism in that sense except for historical
accounts.
>>But the term Darwinism is still used widely in contemporary references,
so,
>>to be meaningful, it must mean something else. I have suggested a
reasonable
>>meaning for it, and it's the one that I intend to use. At least I've
defined
>>what I mean by it, which is more than can be said of most people who use
the
>>term.
>
>For me, Darwinism means two things:
>1. Evolution in general.
>2. Pure gradualism; no leaps in phenotypic evolution.
>
>#1 Everybody is happy with #1, but #2 is dubious. ID people are eager to
>lump the two together, so that #1 suffers from association with #2. When
the
>term 'Darwinism' is thrown around, this confounding of meanings is bound
>to occur. That's why scientists don't use the term; it's mainly used by ID
>advocates and those who get sucked into arguing with them.
I agree. But that still leaves the need for a term to refer to the modern
understanding of the evolutionary mechanism. Some people use "neo-Darwinism"
or "modern synthesis". Apparently "modern synthesis" is the most up-to-date
term, but it's very awkward. Phrases like "he's a modern syntheticist", or
"this is a modern synthetic view of origins" are horrible (and not generally
used). Perhaps I'll use "neo-Darwinism" in future. But I'm open to other
suggestions.
>>Perhaps it would be better to avoid the term altogether. But none of the
>>alternatives seem to be any clearer.
>
>If alternative terminology distinguishes evolution-in-general from
>obligatory phenotypic gradualism, that would seem clearer than a
>term which does not make such a distinction.
>
>>>Is the point that gradualism is saved if only we focus on the 'real core'
of
>>>things, the genetic level? How do you quantify and compare genotypic
>>>complexity? You don't seem to want to judge by the morphological effects,
>>>you seem to want to come full circle and judge genetic mutations by their
>>>base-pair morphology, their most meaningless aspect. It's like talking
>>>about ink and fonts when the topic is literature.
>>
>>If you don't like my definition of gradualism, that's OK--don't use it.
>
>I am an advocate of macroevolution, I think it has been a significant
>mechanism in evolutionary history. I have to wonder what is going on
>when people suggest that large sudden phenotypic changes--such as
>Siamese-twinning or drastic loss of anatomy--are 'really' just small
>changes, because they flow from genotypic changes, and genes are
>just little bitty things. What exactly are they trying to defend?
If you're using "macroevolution" to mean the ocurrence of large phenotypic
changes in one generation, then I'm not the only one who is using terms in
non-standard ways! The word is normally used to refer to evolution at and
above the species level.
I was very careful, in my own definition of gradualism, to emphasize that I
was talking about small increases in genotypic complexity, not small
phenotypic changes.
The occurrence of sudden phenotypic changes is quite compatible with the
modern understanding of evolutionary mechanisms. The reason I reject your
segmentation theory (and why evolutionary biologists would probably reject
it if they were aware of it) is because the particular evolutionary pathways
that you propose are implausible, and you reject other pathways without good
cause.
>>But the version of gradualism that you like to argue against is not one
that
>>anyone wants to "save". It's a straw man.
>
>OK, what is the proper version of gradualism?
I don't say there is a "proper" version of gradualism. It's not so important
what terms you use, as long as you're careful to define what you mean by
them and then use them consistently. What's important are the arguments and
theories. And the theory that you attack under the heading of "gradualism"
is not one that's accepted by evolutionary biologists today.
I think the evolutionary mechanism that I've described as Darwinism and
gradualism is the one that's generally accepted today, regardless of whether
other people would use these terms to describe it.
You seem determined to find a meaning of gradualism to attack. Well, one
meaning (the traditional one) is obsolete, and the other (mine) is
compatible with large phenotypic changes (or "macroevolution" as you call
it). So it looks like you'll have to find another target to attack. It's not
my job to give you one.
>>If that variation is random (as you define it below), then gradualism (in
>>the sense that I define it) *is* essential, because substantial increases
in
>>functional complexity within a single generation are too improbable. (I
>>should have written "functional complexity", instead of just "complexity",
>>since any old random collection of parts can be complex.)
>
>A change from a single cell into a chain of such cells is a big change
>in functional complexity in the real world. Likewise with higher organisms
>suddenly giving rise to chains of identical organisms. If you just want
>to keep focusing on that one segment that is unchanged in itself (for the
>moment) then you are missing something major. If you don't think
>macroevolution has occurred in evolutionary history, you can argue
>against anybody's specific macroevolutionary claim, but you can't
>just define macroevolution away.
I'm not trying to define anything away. I've been very careful to
distinguish between definitions and arguments. But I may have caused some
confusion by my choice of the term "functional complexity", which I realise
now is ambiguous. The word "functional" has two distinct meanings: "having a
function" and "related to function". I meant the former. It should also be
clear that I was referring to *genotypic* complexity, since I cited my
original definition (but I could have made this clearer). So, by "functional
complexity", I meant "genotypic complexity which has a function", not "the
complexity of the phenotypic function", which is how you've interpreted it.
For example, pseudogenes may be very complex, but most of that complexity
has no function, because the genes aren't expressed. Inserting a load of
randomly scrambled base-pairs into pseudogene sequences could mean a large
increase in genotypic complexity, but this additional complexity would have
little or no effect on the complexity of any phenotypic function.
Anyway, given the confusion it seems to be causing, I'll try to avoid the
term "gradualism" in future.
>>Maybe my use of the word gradualism is only confusing the issue. I thought
>>it was useful to have a word to sum up the limitation on the kind of
changes
>>that can be made by natural evolution in a single step, and there doesn't
>>seem to be any other word available.
>
>There is absolutely no logical limitation on what can be achieved in
>one step. This is about what probably has happened in a complex
>evolutionary history, not about natural laws. There's no point in
>talking about limitation in a general sense, because there is no
>general limitation.
It should be obvious that I'm talking about practical limitations, not
logical ones. Logically, I suppose atoms could randomly assemble to form a
human being in a single step. But we all know that this is not a practical
possibility.
Similarly, your segmentation theory is a logical possibility, but too
unlikely to be considered a practical one.
Richard Wein (Tich)
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