On Feb. 19 you picked up my quotation of Darwin, "Only those variations
which are in some way profitable will be prserved or naturally selected."
To which you replied, "Current evolutionary theory, however, recognizes that
neutral variation is also possible and can persist, although there will be no
strong influence to keep a neutral innovation. Even slightly deleterious
variations can survive if the negative inpact on fitness is not enough to
drive it to extinctin (e.g., genetic diseases that do not cause significant
harm until post-reproductin age). In small populations or in regions with
limited crossing over (Y chromsome, mitochondrial DNA, et.), population
genetic show that mildly delecterious mutations can become predominant in a
population despite contrary selection."
(snip)
You concluded with the statement "Thus, just about anything can have an
evolutionary explanation. Whether or not the explanation is correct is
another issue."
Darwin, however, wrote, "Natural selection will never produce in a being any
structure more injurious than beneficial to that being, for natural selection
acts solely by and for the good of each." (*Origin*, Everyman's Library, p.
187).
Darwin had good reason to make such a statement. Earlier he had presented a
long argument, the heart of his theory of evolution, that natural selection
produces modifications in species and varieties that then produce new
species, and eventually after thousands of generations, new genera, and even
families, and orders. So "natural selection, act[ing] solely by and for the
good of each", was tied directly to the production of higher taxonomic levels
of organisms. One of Darwin's implicit criteria of natural selection was
whether it moved the being toward a new species or higher taxonomic level of
being.
None of the examples you presented are tied to the production of new species,
or genera in the manner explained by Darwin. In the strict Darwinian sense
they are not produced by natural selection, and should not be called
evolution.
You conclusion that, "Thus, just about anything can have an evolutionary
explanation" represents a real barrier to scientific progress. I have
serious objections to that answer. Its danger is that it forestalls any
search for an alternate explanatory theory for the examples you presented.
Is there any other non-evolutionary explanation for the examples you gave? I
think there is. Your examples appear to have this in common, that they
exhibit varying degrees of increasing decline and disorder in various
biologic lineages. The populations accumulate neutral mutations (probably
adding to junk DNA), to say nothing of accumulating mildly deleterious
mutations. Why aren't these mutations removed from the germline? One answer
may be the gradually declining effectiveness of repair mechanisms in the
genome. What is happening then is not evolution, but a slow process of
decline and aging of the germ line.
I am aware that evluotionary authors rise up in arms at any suggestion of
aging in the germ line of phyletic lineages. Any evidence that looks like
phyletic aging in the fossil record or in current biology is swept under the
rug of their infinitely stretchable definition of evolution. There motto is
what you stated, "Just about anything can have an evolutionary explanation."
Incidentally, the concept of "of increasing decline and disorder" is the
definition of *aging* given in the series of articles entitled, "Patterns of
Aging" in *Science* July 5, 1996 (p. 54). All individual organisms and large
groups of genetically related aniamls eventually show signs of increasing
decline and disorder, evolutionary authors nothwithstanding. Aging is
heritage of all living systems, be they large or small, short-lived or
geologically-lived. Aging is part of developmental paradigm which differs
significantly from the evlutionary paradigm.
So this is my long answer to the examples you gave: They are showing signs
of increasing decline and disorder--i.e., the process of aging--not
evolution.
Bob DeHaan