>You understate the discrepancies and problems. Take the origin of life.
>Natural selection accounts for how cells and organisms adapt and survive, but
>says nothing about the _origin of life_. This is not a mere discrepancy or
>problem. This is a fundamental matter, and laboratory research on it has
>practically ceased because of the intractibility of the problem.
<snip>
>Take the orgins of transitional forms. Why did
>mammals leave their terrestrial environment to become seagoing whales when
>they were presumably reasonably well adapted to their terrestrial environment
>and any shift toward becoming a whale would only decrease their immediate
>adaptation to their current environment, and should be eliminated. In short,
>evolution is generally silent on the topic of origins. Would you agree?
There _is_ very much active research, both field and laboratory work, on
the origin of life. Many new approaches have been pioneered in recent
years. I have already posted references to some major symposium volumes on
the topic both here and in a _Perspectives_ essay a year or so ago.
Within my own field, there is a huge literature on the origins of new taxa.
Developments in both genetics and our understanding of the fossil record
have revolutionized our picture of the history of life. You seem to hold
to the now discarded view that all evolution is phyletic and orthogenic.
Your objection above to transitional forms evaporates if an allopatric
speciation model is applied.
A common image used to communicate how a species population can move from
one adaptive peak to another is to visualize a "landscape" in which peaks
equate to well-adapted genomes. A species will occupy an _area_ of this
adaptive landscape because of genetic variability with the species.
Mutations arising within the species cause the "area" to shift about its
adaptive peak. Peripheral populations of the species can thus explore the
selective value of new mutations perhaps discovering the low foothills of
another adaptive peak. Selection for that new adaptive peak requires a
reduced gene flow with the larger population - which is why geographic
isolation is likely a common prerequisite for speciation.
>Evolution has also generally failed to solve Mivart's dilemma, which applies
>to many transitions: "Natural selection is incompetent to account for
>incipient stages of useful structures." How does natural selection account
>for myriad of incipient stages in the transition of terrestrial mammals to
>seagoing mammals, when those incipient stages decrease their current
>adaptation to the land environment and do not increase their adaptation to the
>sea? I do not consider this a minor discrepancy. Gould has said that
>Mivart's dilemma has never been resolved.
The known transitional forms between mesonychids and whales, and between
varanid lizards and mosasaurs, are obviously quite well-adapted to their
niches. Since when are amphibious forms poorly adapted to their
environments? Where exactly in these transitions to you see hopelessly
unadaptive stages?
Keith
Keith B. Miller
Department of Geology
Kansas State University
Manhattan, KS 66506
kbmill@ksu.ksu.edu
http://www-personal.ksu.edu/~kbmill/