>>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.>>
There are many research thrusts at the problem. You named some in your essay.
But my claim is that natural selection has not contributed to the
understanding of the origin of life, the origin of a biological cell. Is that
too much to ask of NS?
<<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.>>
I am interested in long term trends of phyla in the fossil record. I am
interested in phyletic origins, viscissitudes, and their fates. I am
interested in why animal groups are organized in a hierarchical fashion, why
there are no crossovers among phyla once they were set in the Cambrian. I am
interested in why phyletic lineages show classic signs of aging after they
pass the peak of their development. I am interested in what drives the
formation of transitional forms. Whether this is all discarded phyletic ond
orthogenic and whatever is not my concern.
<<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.
>>
I have tried to understanding your "landscape" metaphor, without much success.
Can you plug real life species into your metaphor to show how it works in
geological time? What brings about selection in the foothills? It seems to
me, if I may say, that the "landscape" metaphor is more remote from biological
realilty than are Darwinian mechanisms.
Best regards,
Bob