><snip of my own remarks>
>Richard
>Could you please clarify what you mean by Darwinism, and in what respect you
>disagree with it, as there seems to be a great deal of confusion about this
>term.
Chris
Well, I don't really have a good one, because Darwinism is not, strictly
speaking, a well-defined concept, but I think it *would* exclude merging of
two organisms (as you describe below). And, pure and perfect Darwinism is
definitely gradualist, though Darwin has been said to have been reluctant
to accept strict gradualism (which itself needs defining, in my opinion).
But as Gould points out. gradualism is clearly not essential to the basic
process of cumulative variation and selection.
Richard
>I think that few people use the term to mean Darwin's understanding of the
>process of evolution, because we know now that Darwin got some things wrong,
>and, used in this sense, no-one is a Darwinist.
>
>For the record, I use Darwinism to mean the theory that evolution occurred
>by purely natural (non-intelligent) processes, and that the processes which
>are responsible for the evolution of complexity are random variation and
>natural selection.
Chris
With a suitable definition of "random" (i.e., random with respect to
whether a variation is good for the survival and reproduction of the
resulting organism (if any).
>Richard
>This definition of Darwinism implies gradualism, in the sense that large
>increases in complexity cannot occur in a single generation. However, it's
>important to note that we're talking here about genotypic complexity,
>because most random variation occurs at the genotypic level, and a small
>change in the genotype can result in a big increase in phenotypic
>complexity. For example, an organism may have a complex gene which is
>unexpressed and a simple mutation may "switch on" this gene. Also (Cliff
>please note), the merging of two organisms by symbiosis (as is thought to
>have occurred in the evolution of the eukaryotic cell) is not a violation of
>gradualism, because it does not involve the creation of new complexity, but
>simply the combination of existing complexity from two organisms into one.
Chris
Though it may not be a violation of gradualism, it certainly *does* create
new complexity; the resulting new organism may be significantly more
complex than either of the two original organisms, at least in principle. I
think it will generally only *work* when the new genome is only slightly
more complex than the original, because of the improbability of two quite
different genomes producing a biologically viable result.
The complexity of the overall *situation* will not necessarily be more
complex (or at least not much more), because, though each initial genome
might be simpler than the resulting genome, they are *two* genomes. If we
join the strings "aabababccde" and "ouioliljooo" we get
"aabababccdeouioliljooo," which is more complex than the initial strings.
But the initial strings as a pair are more complex than the resulting
string *because* there are two strings.
If the two initial cells were similar enough, then, though the resulting
cell would still be more complex than either of the initial cells (assuming
redundant genetic bits were cast out), it need not be *much* more complex.
We might merge "abcde" with abcx" to produce "abcdx," for example (and
"abcdx" is more complex than either of the original strings). This sort of
merging would be compatible with gradualism. But, it would not necessarily
be the case that all such mergings would produce such slightly more complex
results.
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