>There are a variety of implications that follow. For example, physical
>isolation over prolonged periods becomes the classical explanation for
>species diversification.
Isolation alone isn't a satisfactory explanation for all physical variety. Similar environments should produce results. Of course there are parts of the world that have been isolated for very long periods. Which result in an environment appearing the same, in terms of climate etc., but being entirely different in the important respect that there are and have always been different competitors.
So it isn't just a matter of physical environment, even when we include other flora and fauna as a factor in the environment. Natural history itself influences evolution. Dinosaurs probably couldn't evolve again, because rats and birds would eat all their eggs.
> The source of variation among individuals is
>random mutations which are then culled by selection, in effect
>tailoring them to be adaptive. Incremental changes over large
>quantities of time account for gross differences. And finally that
>natural selection among individuals accounts for all evolutionary
>diversity and variation that we see.
>In contrast, first Gould proposes that selection operates on several
>different levels simultaneously and selection is not necessarily
>restricted to individual organisms.
I'm don't see how this is saying anything different?
> Second that instead of incremental
>change, there are long periods of stasis, interrupted by shorter
>periods of great change (punctuated equilibrium).
Yes, the evidence seems to support this "punctuated equilibrium". But I don't see any necessary contradiction between that and Incremental changes over time. Surely the evidence is that both are true. Incremental changes to species happen gradually continuing, unless and until some drastic change in the environment upset the prevailing ecological balance, forcing drastic changes in living organisms.
Both of these sorts of change are inevitable really.
>Third, that there
>are more processes involved in generating changes than just random
>mutations and at least some of these processes are essentially
>interactive.
There can't be anything except random mutation, unless some other species has been dabbling in genetic engineering before us? But in any event, all adaptions must necessarily be interactive, in that a change in one species is likely to have implications for other species. (No species is an island.)
Obviously there is a large degree of genetic variety in any species which allows a species to adapt somewhat, but this genetic variety ultimately springs from random mutations in the past. Non fatal, although not necessarily useful mutations.
So, this doesn't seem to be a theory that is contradictory with the original one.
>And, that because selection effects different levels
>beyond the individual, it also works on different time scales. And
>lastly that all of these revisions interact together as an ensemble in
>which no particular one is more important than the others.
Again, I don't see that this is saying anything new.
>So the problem with reading those passages of Gould is that most of
>this has to be on your mind in the first place in order for any of it
>to make sense.
So you already need to be familiar with what he is saying in order to understand what he is saying?
>I am not a scientist or specialist. My father-in-law was a botanist
>who studied the co-evolution of plants and pollenators, I used to work
>for a biophysicist studying plant growth and hormone changes under
>variations of light and gravity (direction), and have read a great
>deal out of interest. And I have enough bio-science textbooks around
>to consult, if I get lost.
You're way ahead of me. I do have a little menagerie of ducks, chooks, guinea pigs and so forth around the house and I like to potter in the garden. But that's about my only qualification. You'll have to be teacher then, but I'm an absolutely awful student, so you're in for a terrible time.
>In general, reading is considered a relatively minor skill. In my
>opinion, reading is not a minor skill. It only appears to be, since
>most reading material is pretty minor stuff. Most people, including
>me, expect to understand immediately what is written as long as there
>are no formulas or really bizarre words in use. It is not a common
>experience to read something as dense and technical as those four
>paragraphs. When I came across them, I was buzzing along at a usual
>rate and suddenly slowed down to a crawl as if I had just hit a mud
>slick. Wheels are spinning and there is no forward movement. Damn,
>what was that? So I re-read them several times to follow as much as I
>could, get my orientation corrected, and study the passages and think
>on them.
Yes, I re-read them several time too. I discovered you can over-do that, after a while it starts to make even less sense. Reading isn't the crucial skill BTW, understanding is the hard part. Especially understanding new ideas, that can be very hard.
>All of this relates to another thread from a couple of weeks ago, in
>which Kelley asked what about Gould and Kuhn. I don't know yet. I went
>back re-read about three quarters of Kuhn's Scientific Revolutions,
>and I'll plug away at Gould.
I saw the earlier thread.
>So, I don't blame you for tossing your head, what th bloody f** is this
>jerk on about? On the other hand, it ain't an op-ed piece either.
Maybe, but I can but apply the same techniques to analysing it. I have to work with what I have.
My tentative conclusion is that Gould has some minor refinements to add to the understanding of the mechanics of evolution. The principles remain the same.
Bill Bartlett Bracknell Tas