Re: [asa] The term Darwinism

What exactly is macroevolution?

As for "Darwinian", there is a definition within evolutionary biology,
namely the idea that different factors are involved in species-level
or higher changes than just the ordinary everyday population changes.

However, in the context of ID, YEC, etc., "macroevolution" is
generally used to mean "evolution I don't believe in". This ranges
from Wells and Johnson denying within species changes (e.g.,
unjustified attacking of the peppered moth example) through the
popular "Every species created separately" position (often promoted by
Ross)-never mind all the species that are being created in lab and in
the wild by ordinary processes- to positions accepting evolution
within "kinds" (Kurt Wise is trying to do this; to me it looks like an
attempt to reinvent evolution within a YEC framework) or accepting
most of evolution, like Behe. As such, anything that seems persuasive
can be dismissed as mere microevolution and the major differences in
position between, e.g. Wells and Behe, can be glossed over.

> 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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