RE: [asa] (macroevolution) (was: The term Darwinism)

Dr. Campbell said:
" There's no magic, hard and fast line, between purportedly "macro"
and "micro" events. However, I would note that we may be talking at cross purposes here.
Your statement could be taken in two ways
a) I personally want more evidence.
b) Evolution is wrong because we don't have that evidence.
b is unreasonable because we do not have the means to produce such evidence."

Specifically this sentence:
" b is unreasonable because we do not have the means to produce such evidence "

I disagree. I think the DNA evidence for human evolution (pseudogenes and fused chromosme 2) is all that is needed to demonstrate macroevolution (apelike creature to human). Dr. Campbell- you don't think this evidence demonstrates, conclusively, that macroevolution happened?

...Bernie

-----Original Message-----
From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu] On Behalf Of David Campbell
Sent: Wednesday, July 08, 2009 11:11 AM
To: asa
Subject: Re: [asa] (macroevolution) The term Darwinism

> You have in essence argued that we cannot give full evolutionary pathways --
> not even full hypothetical evolutionary pathways -- for major organs and
> systems, for several reasons, notably (1) we simply do not yet have the
> understanding of the genome necessary for the task, and (2) we cannot
> reconstruct the environments accurately enough to be sure how selection
> would have operated.
>
> My point exactly.  And the logical follow-up question is:  if evolutionary
> biologists are lacking the above knowledge, how can they be so *certain*
> that microevolutionary processes can simply be extrapolated to generate
> macroevolution?  It is one thing to say that macroevolution *may* be
> explicable via roughly Darwinian processes; it is another thing entirely to
> say that "science" has proved this, or that the extrapolation is so
> unproblematic it does not even need to be critically analyzed.

Because all that we do know about the systems points that way, with
the caveat that I presume you are including all sorts of "natural"
processes under the scaling up from microevolution to macroevolution.
(I.e., there are factors besides day-to-day population dynamics
involved in macroevolution, though the relative role is highly
debated. If these factors are entirely describable by natural laws in
their physical effects, I assume that falls under your category of
scaling up from microevolution to macroevolution. For example, the
asteroid impact at the end of the Cretaceous is an event that played
an important role in the course of evolution, clearly outside the
realm of population genetics, but it was a "natural" event.). Again,
macroevolution must be precisely defined to meaningfully talk about
it. There's no magic, hard and fast line, between purportedly "macro"
and "micro" events.

However, I would note that we may be talking at cross purposes here.
Your statement could be taken in two ways
a) I personally want more evidence.
b) Evolution is wrong because we don't have that evidence.

b is unreasonable because we do not have the means to produce such
evidence. a reflects individual judgement and as such is not
necessarily unreasonable, though it can be if either the standards are
uneven (the usual human approach being to accept things one wants to
believe on much less evidence) or ridiculous (e.g., some "if God
exists, why doesn't He do X").

> Yes, a rudimentary version of an eye which actually *works* (however
> poorly), might be useful (e.g., a crude, light-sensitive spot on a
> one-celled creature), but an eye which depends on an arrangement of
> complicated parts (iris, cornea, retina, various fluids, a whole bunch of
> co-ordinated muscles, etc.), but is missing some of those parts or has some
> of those parts broken (so that the whole system cannot work) would not be
> useful.

Not except tautologically. Eyes range throughout the spectrum from
very simple to very complex. More complex eyes are better at seeing
particular things (exactly what depends on the type of eye, e.g.,
compound eyes are rather better for sensing motion than making
images). On the other hand, they probably have more vulnerabilities
to different thigns that could go wrong.

Unless I have my glasses, anything more than about a foot away is
blurry. However, I can still avoid obstacles, detect large organisms,
tell if it's day or night, etc.; I can also see in detail if things
are very close.

The nautilus has a good eye built on the pinhole camera pattern. Not
as effective as the fully developed eye of an octopus or squid, but
pretty good and definitely useful.

Most mammals are colorblind, yet they manage OK. Compared to many
birds, we're rather colorblind-they can see many more.

The idea that the eye is an irreducibly complex structure is
incorrect. Any sort of light/dark detection is useful, so a system
that doesn't function all that well is still useful. Improvements are
generally useful (except when they are in directions that are not or
no longer useful, cf. the loss of sight in many cave-dwelling
organisms.) Of course if you do something like sever the optic nerve,
the eye doesn't help much.

> A computer with a keyboard which could only type the letter "e"
> would be useless for word-processing, for example, even though all the other
> components of the computer worked just fine.

However, it could be used to produce some symbolic system, cf. my
professor recalling early computing, making a graph using spaces and
x's.

> So anyone who believes that macroevolution produced the human camera eye must propose intermediate
> stages, describing all the organ parts necessary to each of those
> intermediate stages, and must also propose mutations that would allow one
> stage to progress to the next one, retaining all or most of the old function
> while adding new elements that would eventually lead to the new and improved
> function.

No, this is saying that everyone must adopt your standards. However,
it should be noted that adding on new function is not particularly
difficult. The example of going from red/green colorblind to
three-color vision (what non-colorblind humans have) is a well-studied
example. The pigments detecting red or green are quite similar and
diverged rather recently. Most South American monkeys are red/green
colorblind, but within some species both red and green alleles exist.
As in humans, this is on the X chromosome, so males are haploid for
the gene and either seee green or red better but can't especially
distinguish them. Females, however, have two copies and may have
color vision if they are heterozygous. Duplication of the gene could
easily result in making three-color vision standard, as happened in
the old world monkey-ape-human lineage. (Color isn't so useful at
night; most mammals are primarily nocturnal and do fine without the
red/green sensitivity. Finding ripe fruit, as many primates do,
however, makes color more important.) Thus, a basic description of
each stage is possible in cases such as this where we know the main
genes and know the previous stage. However, as far as I know we don't
have full details about every gene that influences what goes on in the
brain in the transition from two color to three color vision.

We do know a good deal about the physical changes involved in skeletal
parts of well-studied groups of organisms, e.g, the changes in jaws
from fishes through the various groups of land vertebrates.

> Regarding your final analogy, note that the question, "When Sally threw the ball on this particular date, where did it go?", contains a built-in and unproved assumption, i.e., that Sally in fact threw a ball.  If we take "Sally" to be an analogue of "macroevolutionary processes", then we see the unstated assumption of macroevolutionary theory, i.e., that there exist entirely natural processes of biological change capable of building radically new organs and body plans.<

Actually, I was thinking more in terms of the ball's trajectory, how
long she had to stay in her room after it broke something, etc. as
being the macroevolutionary processes.

We know quite a lot about the physical forces governing the trajectory
of a ball. Likewise, we know quite a lot about the basic mechanisms
of genetics, selection, drift, etc. However, in studying evolution we
are generally not too interested in "how might one get from point A to
point B" but rather in "exactly how did it happen, including side
excursions".

Entirely natural processes of biological change capable of building
radically new organs and body plans do exist, although the description
"radically new" conceals the fact that in most cases the beginnings
would not seem all that radical or new; only the long term outcome of
the change appears so different. ID advocates generally claim that
those processes are too inefficient to build things within a
reasonable amount of time, but mutation and selection do exist and
have the capability of producing something given enough time.

>  Yet if all we know is that macroevolution *happened*, but cannot account for *why* it happened, then it is premature to assume that the causes of the process were entirely natural. It is the presumption (without proof) that the causes of the process were wholly natural that ID proponents greet with skepticism.  How can we know this, given the huge gaps in our understanding -- gaps just conceded by you -- regarding what genes control the various structures and functions?<

Part of the issue lies in the perceived size of the gaps. Not knowing
in detail what every single gene was doing doesn't bother me a bit.
Evolutionary models work. Sure, I'm puzzled as to what's going on in
Campeloma DNA seqeunces, but I know that a) I have a very patchy
picture of the genus so far, b) one of the genes is known (by me) to
often be polyallelic, c) polyploidy could make the picture very messy.

> Wouldn't it be a more accurate -- not to mention scientifically modest -- statement of our current knowledge to say that there *may* be a wholly naturalistic explanation for the fossil record, but that we are nowhere near having such an explanation in hand?<

Not entirely, for in fact evolutionary models work very well. It is
true that we don't have everything figured out, and that is often not
conveyed well, if at all. However, no glaring problems are evident
(unless limited workers and funding count) -work is progressing on
many fronts. Additional considerations related to one's assumptions
about the likelihood of non-naturalistic events in the course of
evolution are, of course, relevant. ID would do well to spend more
time thinking about why one would expect to find non-naturalistic
events and when and where, instead of simply demanding to find
"fingerprints" in evolution.

Conversely, ID ought not to claim that the absence of a naturalistic
explanation is proven, or near at hand. Is it possible that
conventional evolutionary models will run into an unambiguous brick
wall? Yes. Of course, there might be some different naturalistic
explanation instead; that falls short of proof of ID, but probably
such a discovery would tend to point towards ID. ID has done itself a
major disservice by making careless claims of having already achieved
proof, often clearly incorrect claims. It sounds better for marketing
to the masses but discredits itself.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
To unsubscribe, send a message to majordomo@calvin.edu with
"unsubscribe asa" (no quotes) as the body of the message.
To unsubscribe, send a message to majordomo@calvin.edu with
"unsubscribe asa" (no quotes) as the body of the message.