Re: [asa] The term Darwinism

David:

Your eloquent answer below makes my point far better than I could have made
it.

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.

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. 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. 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. So if the stages of the eye went from, say, 3 interacting parts,
to 7 interacting parts, to 13 interacting parts, to 22 interacting parts,
etc., a macroevolutionary account would set forth each of these stages in a
separate chapter of a book, describing them anatomically and functionally,
explaining the genetic basis of each stage, and then proceeding to explain
the transition to the next stage. There would need to be as many chapters
in the book as there were hypothetical stages. But this is not the way
evolutionary biology is ever written. Or if it is written in this way, I
have yet to see any examples.

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. 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?
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?

Cameron.

----- Original Message -----
From: "David Campbell" <pleuronaia@gmail.com>
To: "asa" <asa@calvin.edu>
Sent: Monday, July 06, 2009 2:56 PM
Subject: Re: [asa] The term Darwinism

>> 2. The reason I suggested a 500-page book is that 500 pages is the
>> minimum that would be needed to document the changes for any major organ
>> or system. Every step of the way -- and there would be hundreds of
>> steps -- would need diagrams of the genome with explanations of the
>> substitutions or deletions, diagrams of the proposed physiological
>> changes corresponding to the genomic changes, a discussion of the
>> environmental aspects (selection pressures acting on each change, etc.),
>> and so on. I do not find it surprising that such detailed works have not
>> appeared, as I believe that Darwinian explanation is mostly speculation,
>> ad hoc non-mathematical reasoning, and bluff.<
>
> A more important reason for the absence of such works is that it is
> technologically impossible. Such a description would only be possible
> if we had full knowledge of all the genes influencing whatever
> feature/organism and their exact functions. Bacterial genome
> sequences were big news less than two decades ago; sequences were big
> news three decades ago; computer power is also dramatically
> increasing. The general coverage of genomic sequencing across the
> eukaryotes is still very poor, and even in well-studied model
> organisms such as fruit flies, humans, mice, nematodes, or yeast we
> don't know what every gene does (particularly given that "gene" must
> include stuff like microRNA, not just enzymes). There is rapid
> progress ongoing in the field, and these data may be possible to
> obtain before long, but at present it's just not possible.
>
> Even with full details on the living things, this does not give us all
> the information that we would want about what happened in the past.
> Gene sequences for ancestors can be modeled by comparing the sequences
> in descendents and reconstructing a plausible ancestral form. This is
> especially promising in cases where we have a good idea of the
> ancestral function of a gene, e.g. where a gene unique to a particular
> group of organisms shows similarity to another gene from a more
> inclusive group of organisms, it's likely that the unique gene arose
> from an ancestral form of the other. Such studies have been done for
> a few specific genes.
>
> There are also a few credible reports of fossils preserving evidence
> of molecular sequences, as well as a lot of non-credible ones. (Amber
> seals water in, which is bad for DNA.) However, these will very
> probably be limited to fairly durable molecules, especially ones
> closely associated with hard parts.
>
> Reconstruction of past conditions can be done with varying degrees of
> precision, depending on the quality of the fossil record. However,
> exaptation shows that it's hard to be absolutely certain what the
> precise selective factors involved in a particular situation might be.
> Also, some key elements of the environment do not preserve well
> (e.g., soft-bodied organisms, exact weather, regional-scale
> geography), just as some environments do not preserve well.
>
> Yet another factor is that the market for such research is generally
> poor. There are some applications to medical and biotechnical fields,
> but as a whole it's entirely up to academia. Even within academia,
> there's not nearly as much support for "academic" research as there is
> for research that can bring in lots of money from medical or biotech
> or even agricultural grants. The number of job postings for
> paleontology or evolutionary biology is quite low, especially if you
> remove positions for students to work on evolution within a model
> organism or pathogen from the tally. (I'm also not counting "we want
> someone to teach premedical courses and maybe do the evolution course
> on the side.")
>
> Of course, anyone is free to set a level of proof desired for
> something, but it is unreasonable to expect such a book to already be
> available.
>
> That's not to say that we can't trace the basic evolution of a
> particular organism or feature with a fair amount of detail. Eyes,
> for example, are rather easy to explain. Plenty of organic molecules
> absorb certain types of electromagnetic radiation, so finding
> light-sensitive pigments is not too hard. Being able to detect and
> respond to light levels is generally useful (e.g., getting light for
> photosynthesis or keeping in the shadow to hide from heat, UV,
> predators, etc.). Even a rudimentary version is useful. Increasing
> complexity of the visual system is generally advantageous, so a
> gradual accumulation of improvments is quite unsurprising. Details of
> the color vision system in humans and related primates has been
> studied in detail, since we have relevant gene sequences and a model
> system in the South American monkeys, which are generally red/green
> colorblind. On the other hand, people with all sorts of vision
> deficiencies can function reasonably well-any problems with the system
> are not automatically fatal.
>
> Much of the evolution of the bivalve shell can be traced in detail.
> Although genetic work is relatively limited, we do have good general
> phylogenies of the group and some genetic data on some of the proteins
> involved in early development of the shell. We can also trace the
> origin of the bivalved shell from a single shell in the fossil record,
> and we can trace changes in shell structure and form through the
> fossil record.
>
>> even when 150 years later it still can't take us from point A to point B
>> in detail, as virtually all other sciences can.<
>
> Actually, it's probably about on par with physics in this regard.
> There are two major differences in the types of questions being asked
> that make the comparison misleading.
>
> First, in evolution we are generally interested in a very complex
> system. Even a very well characterized system like gravity can become
> unsolvable in detail when you are dealing with three or more objects.
> Many of the factors involved in evolution are well-characterized
> mathematically, but many are either probabilistic or not readily
> quantified. If you have a very simple system, then we can make rather
> accurate and precise evolutionary predictions. Secondly, most
> interest in evolution is in reconstructing the history of life-exactly
> what happened in a specific example in the distant past-rather than a
> general statement of average behavior of biological systems. Instead
> of the intro physics question of "if you throw a ball with a certain
> force and angle and ignore everything except earth's gravity, what
> would hapen?", we are asking questions more like "When Sally threw the
> ball on this particular date, where did it go?"
>
> --
> Dr. David Campbell
> 425 Scientific Collections
> University of Alabama
> "I think of my happy condition, surrounded by acres of clams"
>
>
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Received on Tue Jul 7 00:41:17 2009