Gould and Macroevolution

[Almo]

That's where Gould comes in. You stated that the accumulation of micro changes causes macro evolution. Gould disagrees; he thinks there's an even bigger mechanism at work.

I'd like to know more about this. Briefly, what does he propose? I've read a few of his books, and I find him immensely clever.

Edit to list source:
This thread was split from:
http://206.225.95.123/forumlive/showthread.php?t=50276

And the source was BillHoyt.

[KingMerv00]

I'd like to know more about this. Briefly, what does he propose? I've read a few of his books, and I find him immensely clever.

What is the source of that quote?

To my knowledge, Gould was an evolutionist through and through. He merely had some issues with the RATE of evolution.

[hammegk]

In a nutshell:

Per zoologist Dawkins evolution *must* be by gradual, step-by-step, tiny stages, otherwise it couldn't happen at all.

Per paleontologist Gould the fossil record shows it didn't happen that way.

[Garrette]

Not really true, hammegk, though I am not remotely an expert on this.

My layman's understanding of Gould's "punctuated equilibrium" hypothesis is this:

1. A portion of a stable population becomes geographically isolated

2. The isolated population undergoes hereditary mutations in the same fashion as the non-isolated population

3. Environmental factors unique to the geographic area containing the isolated population select mutations in that population which, by chance, would be advantageous even outside the isolated area

4. The isolated population, with its new mutations, becomes un-isolated

5. The new, advantageous mutations, cause for the previously isolated popoulation to proliferate more successfully


The mutations themselves are really no less gradual than in other hypotheses, but the success of the mutated population appears sudden as it spreads out from its isolation.

More than that, I don't think Gould said that this mechanism is exclusive of other mechanisms for evolution.

I'll step back now and let the more educated posters rip this to shreds as I'm sure I've misstated quite a bit.

[Melendwyr]

Part of the hypothesis is the idea that species remain relatively stable for long periods of time. Then, when some condition changes dramatically, speciation events occur relatively rapidly.

Long periods of steady and subtle change broken up by wild evolutionary shifts: that's punctuated equilibrium for you.

For more information, see http://www.talkorigins.org/faqs/punc-eq.html

[hammegk]

Not really true, hammegk, though I am not remotely an expert on this.
I don't see your comments in any way negating mine.


Long periods of steady and subtle change broken up by wild evolutionary shifts: that's punctuated equilibrium for you.
"Wild evolutionary shifts" are not in Dawkins model sfaik (may I call his ideas The Latest-as-of-Today Theory of Neo-darwinist Evolution), and are exactly what Gould points out.


Yeah, I know, semantics & definitions. :)

[Jon.]

Part of the hypothesis is the idea that species remain relatively stable for long periods of time. Then, when some condition changes dramatically, speciation events occur relatively rapidly.

Long periods of steady and subtle change broken up by wild evolutionary shifts: that's punctuated equilibrium for you.

For more information, see http://www.talkorigins.org/faqs/punc-eq.html

It's probably worth pointing out here that "relatively rapidly" means that the "wild evolutionary shifts" take place over tens of millions, rather than hundreds of millions, of years. Also that this theory is not inconsistent with more gradual evolution. Punctuated equilibria is perfectly consistent with slow, gradual evolution. The much-ballyhooed "split" between Gould and Dawkins is nowhere near as deep, wide or important as many anti-evolutionists like to make it out to be. Just read Dawkins' A Devil's Chaplain if you don't believe me.

[Garrette]

I don't see your comments in any way negating mine.Fair enough.

But it's this part that I really take issue with:

Per paleontologist Gould the fossil record shows it didn't happen that way.AFAIK, Gould did not say this. He said the fossil record did not exclusively support this interpretation.

For the rest, read Jon's post. It said much better what I was trying to say.

[sphenisc]

It's probably worth pointing out here that "relatively rapidly" means that the "wild evolutionary shifts" take place over tens of millions, rather than hundreds of millions, of years. Also that this theory is not inconsistent with more gradual evolution. Punctuated equilibria is perfectly consistent with slow, gradual evolution. The much-ballyhooed "split" between Gould and Dawkins is nowhere near as deep, wide or important as many anti-evolutionists like to make it out to be. Just read Dawkins' A Devil's Chaplain if you don't believe me.

It is substantially deeper than you make out.

Under Gould on Richard Goldschmidt
http://www.stephenjaygould.org/people/richard_goldschmidt.html

'major structural transitions can occur rapidly without a smooth series of intermediate stages'

[William Parcher]

'major structural transitions can occur rapidly without a smooth series of intermediate stages'

Rapidly as revealed by the fossil record, or rapidly in real-time? Either would seem to be using the term "rapid" in a relative way.

That statement would lend itself to grand misinterpretation.

[Roboramma]

Has Gould suggested a mechanism for evolution other than the familiar ones of Natural Selection and genetic drift?

I don't think he's a saltationist.

It seems that he's saying that under extreme environmental pressure, populaitons diverge much faster than usual, to the point that you don't see the intermediates in the fossil record - because the process is happening too fast. That doesn't mean that those intermediates don't exist.

But that's my understanding of him. I'm no expert on Gould. Could anyone bring in a quote to show him saying something different?

[Melendwyr]

No, he's not presenting any fundamentally new evolutionary mechanisms. His work is an elaboration on earlier ideas about how speciation takes place.

[sphenisc]

It seems that he's saying that under extreme environmental pressure, populaitons diverge much faster than usual, to the point that you don't see the intermediates in the fossil record - because the process is happening too fast. That doesn't mean that those intermediates don't exist.

But that's my understanding of him. I'm no expert on Gould. Could anyone bring in a quote to show him saying something different?

He's saying "macroevolution is not simply microevolution extrapolated, and that major structural transitions can occur rapidly without a smooth series of intermediate stages."

That is: specifically denying macroevolution is microevolution writ large. It also states 'without a smooth series of intermediate stages', not that they can't be seen in the fossil record; that they don't exist. The rest of the section makes it clear that this is what is intended.
The examples under 'The Return of Hopeful Monsters' (boid snakes and pocket gophers) explain the problem with any intermediates.

This seems to be saltationism.

[Melendwyr]

This seems to be saltationism. Nope. You can get startling deviations from the previous design with just a few mutations in a single generation. Of course, that's usually lethal.

Read talk-origins more carefully, please.

[William Parcher]

At least one of Dawkins' criticisms of Eldridge & Gould's PE theory is that it can cause a person to think saltationism, instead of thinking rapid gradualism.

[sphenisc]

Nope. You can get startling deviations from the previous design with just a few mutations in a single generation. Of course, that's usually lethal.

Read talk-origins more carefully, please.

From talk-origins
"Saltationism (in texts before about 1940 also called "Mutationism" or "Mutation Theory", the view that changes between forms occur all-at-once or not at all) "

[Melendwyr]

That's not what Gould is saying at all. Speciation is the issue, not change-between-forms. In Gould's hypotheses, new species most frequently arise when sudden changes in environment cause small, isolated groups to experience different selection pressures than the main population. Selection works most rapidly on smaller populations.

[sphenisc]

That's not what Gould is saying at all. Speciation is the issue, not change-between-forms. In Gould's hypotheses, new species most frequently arise when sudden changes in environment cause small, isolated groups to experience different selection pressures than the main population. Selection works most rapidly on smaller populations.

To whom was that addressed? The issue was "You stated that the accumulation of micro changes causes macro evolution. Gould disagrees", see OP.

[Garrette]

Sphenisc, I think Melendwyr's comment works as a reply to the OP and to other posts suggesting that Gould was trying to overthrow gradual speciation.

He wasn't. He was offering a modified interpretation.

[Roboramma]

3. Environmental factors unique to the geographic area containing the isolated population select mutations in that population which, by chance, would be advantageous even outside the isolated area

4. The isolated population, with its new mutations, becomes un-isolated

5. The new, advantageous mutations, cause for the previously isolated popoulation to proliferate more successfully
So basically, you won't see this evolution in the fossil record because it's happening on such a small scale that there are very few intermediates and they would be very unlikley to fossilize. But after this new form spreads out, and proliferates, it becomes very common and much more likely to fossilize. Thus you see it's appearance in the fossil record as sudden.

Sorry sphenisc to have disregarded your last post, but, well, this is what I thought Gould was saying before. Can you give me a reason to change my opinion?

[Garrette]

As far as I gather, roborrama, yes. But we have now reached the limits of my knowledge regarding this.

[Roboramma]

Sphenisc, just to continue. I went back and looked at your link after that last post, in case I'd missed something. Reading it I see Gould saying, basically, "Goldschmitt may have been right, we don't know that he wasn't, let's not throw out his ideas which may be valid, until we can say one way or the other." but it doesn't say that he agrees that he was right. Also, it doesn't say that this is what he was saying with Punctuated Equilibrium.

I willing to be shown that I'm wrong - I really don't know that much about Gould - but I think you may be reading too much into that webpage. On the other hand, I tried following the link at the bottom of that page concerning Gould, but it wouldn't open, so I may have missed something there.

[sphenisc]

So basically, you won't see this evolution in the fossil record because it's happening on such a small scale that there are very few intermediates and they would be very unlikley to fossilize. But after this new form spreads out, and proliferates, it becomes very common and much more likely to fossilize. Thus you see it's appearance in the fossil record as sudden.

Sorry sphenisc to have disregarded your last post, but, well, this is what I thought Gould was saying before. Can you give me a reason to change my opinion?

I've provided direct quotations and links as evidence.
Garrette's provided his 'layman's understanding of Gould's "punctuated equilibrium" hypothesis', without links or quotes.

I, naturally enough, consider my evidence stronger on this basis.

The other point is that Gould may have changed his mind. I'm simply attempting to show that Gould disgreed at some time.

OP:

You stated that the accumulation of micro changes causes macro evolution. Gould disagrees.

If you interpret that as meaning Gould always disgreed, then that's more than I'd care to prove. :)

[Roboramma]

I've provided direct quotations and links as evidence.
Garrette's provided his 'layman's understanding of Gould's "punctuated equilibrium" hypothesis', without links or quotes.

I, naturally enough, consider my evidence stronger on this basis.


Of course, but I don't think the quotes you've given show what you think they do. For instance, you quoted Gould saying:
"macroevolution is not simply microevolution extrapolated, and that major structural transitions can occur rapidly without a smooth series of intermediate stages."

Which seems to support your point very well.

But you miss the few words before that: "I wish to defend Goldschmidt's postulate that macroevolution..."
I know you don't think the first words make any difference. But I do. Reading it, I see his defense of Goldshmidt as defending the possibility that he's right. He's saying, don't degrade Goldschmidt, don't dismiss him out of hand. That's my reading of it, anyway. I may be wrong, I'd need to read more Gould to know for sure.
He said, "Goldschmidt said this, and I wish to defend his statement". That's very different from him saying it himself.

Basically, I'm saying that there is a big difference between saying that we should look into the possibilities of other mechanisms of macroevolution, and suggesting that we know that those mechanisms actually do exist.

[sphenisc]

Of course, but I don't think the quotes you've given show what you think they do. For instance, you quoted Gould saying:
"macroevolution is not simply microevolution extrapolated, and that major structural transitions can occur rapidly without a smooth series of intermediate stages."

Which seems to support your point very well.

But you miss the few words before that: "I wish to defend Goldschmidt's postulate that macroevolution..."
I know you don't think the first words make any difference. But I do. Reading it, I see his defense of Goldshmidt as defending the possibility that he's right. He's saying, don't degrade Goldschmidt, don't dismiss him out of hand. That's my reading of it, anyway. I may be wrong, I'd need to read more Gould to know for sure.
He said, "Goldschmidt said this, and I wish to defend his statement". That's very different from him saying it himself.

Basically, I'm saying that there is a big difference between saying that we should look into the possibilities of other mechanisms of macroevolution, and suggesting that we know that those mechanisms actually do exist.

I really can't see any evidence in his article for the distinction you draw. Gould makes the case for Goldschmidt's postulate in his words, he provides Frazzetta's evidence which post-dates Goldschmidt. Most of the rest of the arguments he presents are his own, rather than a repetition of Goldschmidt's (from memory of reading Goldschmidt, I don't have it to hand).

He states "In my own, strongly biased opinion, the problem of reconciling evident discontinuity in macroevolution with Darwinism is largely solved by the observation that small changes early in embryology accumulate through growth to yield profound differences among adults."

{My bold}

There is simply nothing in the article to suggest that "Goldschmidt said this, and I wish to defend his statement" is very different from him saying it himself. People generaly defend other people's statements because they agree with them, (except in the case of lawyers, where they're paid to).
I see no reason to read anything other that agreement between Gould and Goldschmidt in this case (except in the single item of interpretation that he mentions.)

But either way it doesn't make any difference to the argument; either way, by making a case for the opposite, Gould is disagreeing with the OP statement " the accumulation of micro changes causes macro evolution."