In a message dated 4/17/01 1:12:08 PM, email@example.com writes:
<< Senescence in species, especially, and to some extent in genera and
families, seems to me to be obviously explainable in evolutionary terms.
That organisms become better and better adapted to specific environments
seems to encompass a good deal of evolutionary theory. However, the
environment does not remain constant. I think of climate changes; plate
movements that bring separate land masses together and introduce new
competitors, predators, etc.; more subtle changes of various sorts which
a highly specialized group cannot cope with. This would look like
senescence in the fossil record, while fitting exactly into an
I've obviously painted with a broad brush. There are surely more subtle
matters which, if we could but recognize them across strata, would give a
a tighter evolutionary explanation. Then there are such matters as
genetic drift, which do not fit into the notion of becoming better
adapted. These are part of the total pattern. Put together (and since I
am looking on from outside, I believe there must be many other factors
that insiders can supply), there seems to me to be no dissonance between
"senescence" and evolutionary theory.
You have described the process of extinction, not phyletic aging. These are
two distinctly different processes. Aging is caused primarily be internal
factors, not environmental ones, and is characterized by increasing disorder
and decline in individual organisms, and in groups of them. Increasing
disorder and decline can be observed at the phyletic level, that is, in
taxonomic groups, as well as in individuals.
Your response, Dave, illustrates what happens so often when the Darwinian
paradigm is challenged. Immediately someone springs to its defense.
Without, I assume, having given any serious study to the process of aging,
which is extremely complex, especially when applied to phyletic groups, you
have stretched the theory of evolution to encompass it, to your satisfaction,
and perhaps that of others, and have thus disposed of the challenge.
I am in the process of organizing my studies of phyletic aging, but ask your
forbearance for the delay in completing it as I have a serious family matter
that will require my attention for the time being. I promise, DV, to get
back to this topic later.
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