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July 14, 2003

WHATEVER HAPPENED TO PUNCTUATED EQUILIBRIUM?

This is a genuine question, not a rhetorical one.

From the mid-70s up to about 1990, there was controversy about the punctuated equilibrium theory of evolution. You could hardly open a scientific magazine like New Scientist or Scientific American without finding some new argument.

But from 1990 onwards interest in the subject seems to have declined. Am I right about this, or have I just developed a blind spot?

I’m aware that shortly before his death Stephen Jay Gould published a vast book on The Structure of Evolutionary Theory, which I haven’t read, but judging from the reviews it was just a rehash of everything he’d said before. The general lack of excitement at its publication suggests a loss of interest in the controversy.

If I am right about this, what is the explanation? Have biologists reached a consensus on the merits of the case? Or have they just got bored with it?

I have no strong view on the issue myself. What I found annoying about Eldredge and Gould’s approach is the way they exaggerated the novelty of their theory. In particular their treatment of George Gaylord Simpson was outrageous. Their own theory could well have been presented as an extension of Simpson’s idea of quantum evolution, but instead they chose either to ignore him or to mention only their disagreements with him. Of course, the controversy also got entangled with Gould’s crusade against adaptationism, and his flirtation with macromutation.

But on the substance of the issues, I think there is quite a lot to be said for punctuated equilibrium. I could even live with a bit of macromutation if necessary.

Ultimately the prevalence of a punctuational mode of evolution is an empirical matter. The controversy dragged on for so long because the fossil record is seldom good enough to trace in detail the transition from one species to another.

But it strikes me that the controversy took place in the era before DNA sequencing. Surely the new technology should transform the terms of the debate? By comparing the genes of closely related species, isn’t it possible in principle to reconstruct the course and timing of the genetic divergence between them? On a broader scale one could do the same with genera, families, etc.

Maybe a lot of work like this is going on, but if so I don’t think it has yet filtered through to the general scientific public. There has been a good deal of work aimed at resolving disputes in phylogeny (like the relationships of the various invertebrate phyla), but this is not quite the same issue. What I have in mind are questions like: how long did it take for (e.g.) lions to diverge from leopards and tigers? How many gene substitutions were involved? Were they genes with major phenotypic effects, or were there a large number of small changes? Is it possible to estimate the size of the populations during the transition? Were the changes concentrated in the period when the species became reproductively isolated from each other, or were they spread out over a longer period?

As always, I hope someone can point me to relevant work that I wasn’t aware of.

DAVID BURBRIDGE

Posted by David B at 01:10 AM




Godless' fittingly gracious eulogy to the Gouldster, where he mentions [quoting chater 9 of The Blind Watchmaker] how punctuated equilibrium was both unoriginal and presented with absurd hostility to Darwinism. It's no wonder so many Creationists have actually (with much audacity, I admit) quoted Gould to me in their little effort to debunk evolution.

Posted by: Jason Malloy at July 14, 2003 01:35 AM


So as I understand, (please feel free to correct me ruthlessly) punctuated equilibrium is just the observation of differential rates of evolution – ie long periods of stases interrupted by periods of rapid (on a geological time scale) adaptation. Reason for this being that speciation doesn’t occur through transformation of a single lineage of a large population, but involves a splitting off of a sub-population (which because of it small size, adapts rapidly, and then replaces the other non-adapted population).

Darwin, it seems to me, was definitely onto this back in 1860:

" Local varieties will not spread into other and distant regions until they are considerably modified and improved; and when they do spread, if discovered in a geological formation, they will appear as if suddenly created there, and will be simply classed as new species." The Origin of Species, Chapter 14, p.439

Why is PE reason for controversy at all?.. is what I'm really wondering.

Posted by: tara at July 14, 2003 04:19 AM


Some of this (the spandrels stuff on byproducts of adaptation, e.g. male nipples) was ok.

Bah . . .functional shift, again, a basic evolutionary principle since Darwin, who coined a term for it which was preadaptation. "Exaptation" and "spandrels" were more Gouldian non-revolutions:

"Dennett, in his NYR, letter speaks of Gould's "non-revolutions," claiming that Gould's alternatives to genic selectionism are empty. Gould claims that speciation (the rise of new species) differs in its mechanism from the sort of gradualistic changes observed in the genetics laboratory. Gould also claims that macroevolution, the major main trends evolution, depends in large part of species selection rather than individual or genic selection, thus operating at a different level from the microevolution or the sort observed with breeding fruit-flies. Furthermore, Gould denies selectionism, claiming that many traits have not been selected for and are not particularly adaptive, and coins the term "exaptation" to characterize the functioning of a trait which was not previously selected for or adaptive. He claims this is different from the previous, orthodox neo-Darwinist claim of "preadaptation" where a trait previously selected for one function or adapted to one environment is later selected for another function in a different environment. Dennett denies exaptation differs from preadaptation and accuses Gould of tooting his own horn by inventing a new term for a well-known idea. Gould claims that exaptive traits were not previously selected for, and that preadapted traits were so selected for some other function."
Posted by: Jason Malloy at July 14, 2003 07:28 AM


Clearly punctuated equilibrium has reached the fourth stage of debate: "We knew that all along".

My interest in Gould is especially in what he says about contingency, and evolution (and history, including intellectual history) as the alternation and proliferation and decimation. This squares with my understanding of "Evolutionary Epistomology" (originally Popper through Campbell, but it seems to be a live field and I'm not up on it).

It would seem to me that libertarians would be attracted to punctuated equilibrium, since part of it is the idea that critical change can be local and relatively sudden. Evolutionary gradualism, as an ideology, had a suffocating effect. Gould's "Marxist" streak was to a considerable degree just opposition to gradualism and opennness to the possibility of change.

Posted by: zizka at July 14, 2003 07:44 AM


P.S. I read Dennett's Darwin/anti-Gould book, and he is definitely not someone I would want on my side. He repeats his slogans (e.g. "Cranes! not skyhooks!") far too often. When I read Gould I'm always finding interesting little tidbits of history, natural history, or analysis, whereas reading Dennett was like listening to a verbose lawyer or ideologue. He figured out a tactful way to redbait Gould and came reasonably close to Jewbaiting him too.

It doesn't help at all, as far as I'm concerned, that he's an analytical philosopher trying to find a real world application for his pointless specialty.

Posted by: zizka at July 14, 2003 07:51 AM


I think Gould capitalized on several factors that exaggerated his importance during his lifetime.

First, he was a seductive writer, interspercing his observations with learned references outside his field that make the intellectual wanna-bes feel like this is one of their bretheren: a renaissance man like themselves! Freud did it to great effect as well.

Second, his thinking was in sync with current PC thinking. For example, in his view all human races are equal in every meaningful way, man isn't special in this world's history, and 'progress' is just what the current robber barons call the process that got them there, and that bias colors the thinking of all those that disagree with him.

Now he's gone, and a dead man's flattery isn't alluring, so people only quote him for the balast it gives their insights, which isn't much.

His last book was the rambling (1400 pages) manifesto of an overambitious, pathetic man (he probably knew he was dying when he wrote it), testimony to the helpfulness of editors (he never allowed anyone to edit his work), and humility (a man who thinks himself genius is lost), and having an organized theme.

Posted by: eric at July 14, 2003 07:54 AM


When I read Gould I'm always finding interesting little tidbits of history, natural history, or analysis

I agree with this 100%. I don't want to lie, I've read a lot of Gould, and I liked it. I admit Gould is a good author. But it's his erudition that is part of the problem. We can't have an anti-adaptationist group selectionist as the publics #1 spokes-man for the state of evolutionary theory. It creates a damaging misrepresentation of the science. Gould was a master at manufactured dichotomies and paradigms (gradualism vs punctuation, spandrals vs adaptations). Dennett may be a propagandist, but at least his was a more or less representative propaganda. Can Dawkins please be the best compromise? ;)

Posted by: Jason Malloy at July 14, 2003 08:35 AM


He figured out a tactful way to redbait Gould and came reasonably close to Jewbaiting him too.

Also I am absolutely unsympathetic about anyone in Gould's little "Science for the People" clique getting red-baited after the venomous war that they initiated*. I could dig up quote after quote of Gould making inflammatory statements and allusions of this nature (esp. re: fascism) to all sorts of colleagues, spanning decades, w/o the slightest bit of hesitation. And the fact of the matter is, Gould was an admitted Marxist. And he admitted to it influencing his work. I think that this absolutely deserves a critical response.

As for the Jew-baiting - I'm intrigued, and not so sure you might be wrong. Got a page #?

*read the history of that whole sociobiology controversy in the seventies, everyone, even Gould I think, admits that those initial attacks by SFTP were just way, way over the top.

Posted by: Jason Malloy at July 14, 2003 08:55 AM


Jinx, on that Marxism post. Jensen, king of hereditarians, is half-Jewish too, GC. ;)

Posted by: Jason Malloy at July 14, 2003 09:00 AM


If you look at Gould's quote, he was freely admitting to having learned from Marx at one point. What he learned was a version of "the dialectic" (perhaps Engels argument that changes of degree can be changes in kind, e.g. freezing water)which allowed for sudden and discontinuous change against XIX C. and gradualism. It didn't amount to an oath of allegiance to a Marxist party or to Marx's work itself. Dennett also seems to accuse Gould of theism. (The Jew-baiting was done very mildly and quoted one of the leaders of the field whose name I forget for the moment. Smith? Not really a big deal.)

Eric -- rewrite your last sentence? Don't hold back, tell us what you really feel!


Posted by: zizka at July 14, 2003 09:48 AM


Hmm . . . I had always interpreted "learned his Marxism" as a statement of political convictions. But I see that others disagree, and that there is a certain amount of deniability there. Even if not confessed in the most explicit manner, I still see it as the more likely interpretation that Gould was a "reformed" Marxist of sorts (certainly not a Stalinist).

For instance he was on the advisory board of the Brecht Forum/NY Marxist School which describes itself as such:

. . . The Brecht Forum’s New York Marxist School [was established] to use Marx’s uniquely valuable contributions, along with others within and outside of the Marxist tradition, to study conditions today and possibilities for transcending capitalism and building an emancipatory society.

Posted by: Jason Malloy at July 14, 2003 10:15 AM


Clearly punctuated equilibrium has reached the fourth stage of debate: "We knew that all along".

no, always been at that stage, reread the blind watchmaker from the mid-1980s and dawkins dismisses punc eq in like fashion. punc eq makes some interesting empirical observations but gould & neldridge's assertions seem to be theoretically weak in my opinion. some of gould's ideas like levels of heirarchy in evolution don't seem to relate to punc eq in any case. punc eq makes a big deal about "stasis" as being important to peculiar, but "stasis" sounds like another way to state that a species has found an adaptive niche that is pretty stable.

stasis would be more amazing if species regulated their mutation rate in relation to the changes occuring in their environment-but it seems to me that species simply aren't selected for new mutations until their environment/context changes where mutations might be favorable....

blah, blah....

Posted by: razib at July 14, 2003 12:00 PM


OK, so Gould claimed there was a controversy, but there wasn't really? Initially did everyone just say "We already knew that" about everything they accept now, while rejecting others of his ideas which have by now been definitively disproven? I.E., nothing new that was good? Nobody had to change their mind or their tone at all?

Gould was unquestionably politically left in his sympathies. It seems to have been a fairly commonplace European social democracy, though, which of course is not a good thing to most of you guys, but not really Marxism.

Posted by: zizka at July 14, 2003 12:39 PM


so Gould claimed there was a controversy

gould basically said there was something special about certain observations that conventional neo-darwinians had more banal explanations for. gould was a paleontologist, he was trying to explain gaps in the fossil record, the transitional forms, etc. but a technical discussion turned into something far more grand in the public mind because gould had a platform as a man-of-letters (my middle school geology teacher presented punc eq as a 'revolution,' i looked into it and wondered, 'where's the beef?'). what really bugged a lot of biologists is that punc eq was one theory out there that might have overturned a minor applecart in biology-but since gould was such a larger-than-life scientist, the public got the idea that there was a 'revolution' afoot. so the controversy was less about the so-so idea than about the public perception which scientists found irritating. additionally, gould's ideas were taken up and misrepresented by creationists, because he attacked 'darwinism' and 'adaptationism' in strong and uncompromising tones so that quote-lifting and out-of-context-twisting was a breeze.

i think it would be valid to say that gould was an important paleontologist. but an important evolutionary biologist? hm, i don't think so.

as far as gould's politics-dawkins, as a labour party supporter is probably at least as far left as gould, as were others who opposed gould & lewontin's witch hunt. i believe that trivers (contemp of hamilton, williams & price) was a supporter of the black panthers even! the important point was that gould & lewontin had no qualms in turning a blind eye to the explicit politicization of scientific questions by campus radicals turned a dispute over scientific metholody and hypotheses into a food-fight. to this day, many of my left-wing friends who have backgrounds in the humanities start discussions about e.o. wilson under the impression that a man who is a secular moderate democrat is a 'harsh right wing radical.'

Posted by: razib at July 14, 2003 01:07 PM


oh, and i want to add, gould was definately robbin to lewontin's batman in the 70s, it just turned out that batman seems to have retired and robin chugged on. lewontin is an example of a brilliant scientist who is a political idiot-not because he's a marxist & leftist, there are plenty of intelligent leftists & marxists who to me can make intelligent cases, which i disagree with because of normative values, but he doesn't understand his politics in the same way he grasps genetics.

this is the thing i think we need to remind ourselves about scientists-they often hold somewhat more rational world-views politically that PoMo humanists, but they are so ignorant about the details of what views they hold they sound and act just as moronically in this field as their PoMo humanist colleagues. gould btw sounded much less wack about marxism than lewontin-probably because he knew something about it.

ok, my rant is ended.... ;)

Posted by: razib at July 14, 2003 01:29 PM


Well, as a man of letters I'm happy to see our side win for once. The last several centuries haven't been too good to us, you know.

Posted by: zizka at July 14, 2003 02:16 PM


Of course Marxism's main theses in economics have all been thoroughly discredited (falling real wage, falling rate of profit, widening depressions, the disappearance of the state after communist revolutions). And perhaps Marxism wasn't very helpful in genetics (Lysenko). But in philosophy and literature, where anecdotes and theory are impervious to aggregate data, what a useful lens to approach things.

The importance of large vs small changes seems like the debate in economics about the importance of macro vs micro inventions. Microinvention make the most of our daily lives, and gradually increase wealth a great deal. Macroinventions like the wheel, moveable type, the steam engine, nuclear power, are all very important, but what's most important is that they were all somewhat inevitable given the state of knowledge they arose. Most were developed simultaneously elsewhere, and I think implausible any wouldn't be known now in Newton, Faraday, Einstein or Edison died in their childhoods. In the same way, in geological time, I think something like human intelligence was inevitable here, and while it's a Wonderful Life for us today, the accident off the Yucatan peninsula was only necessary for us, but not for intelligent life during Earth's finite existence.

Posted by: eric at July 14, 2003 07:23 PM


Its likely that everything on earth has been invented billions of times before on other planets. If there are infinitely many universes then everything has probably been invented before infinitely many times. The only way we can possibly be novel is in craftsmanship and artistry. These are the hallmarks of great civilisations, not "macroinventions".

Posted by: Sporon at July 14, 2003 08:03 PM


Its likely that everything on earth has been invented billions of times before on other planets.

Only if "likely" means "entirely speculative and not supported by any evidence"...

Posted by: Oleg at July 14, 2003 08:32 PM


I don't think many Gouldists have thought out possible repercutions of punc. ec.
The first one that comes to mind: Immense changes in a population can occur very rapidly. The standard PC argument for race being skin deep is that human populations have been separate for a small number of generations, not long enough for large evolutionary changes to take place.
A equilibrium punk could say, that yes, human populations have been not been separated for long, but rapid changes can easily happen, so the races could be tremendously different.
Another thing, Since evolving is so often a design issue, with trade-offs, relative fitnesses should occasionally change alot. Not a bone issue, but how about diseases, everyone, even BG (before Gould) realized some events could change gene frequencies fast.

Posted by: Rob at July 14, 2003 08:51 PM


Oleg, there are countlessly many galaxies and stars and ours is but one planet circling one star. I consider that evidence of our non-uniqueness. I concur that direct positive evidence is unavailable.

I also note that h-bd types seem to think that the measure of a civilisation is in its intellectual feats. I feel, on the contrary that great civilisations produce intellectual feats because the people living in them have the time and inclination to think about such things. I don't deny that technology brings some material comfort, but for the most part it cannot be enjoyed. I would not want to live in some dirty world of machines and garbage.

Posted by: Sporon at July 14, 2003 09:05 PM


Well, the reserve army of the unemployed is still with us. That's what globablization is all about.

Posted by: zizka at July 14, 2003 09:24 PM


Did Gould ever propose a mechanism of speciation? Because without one the number of species just rachets downward. I mean a group selection mechanism of speciation, something that a marxist might approve of

Posted by: Rob at July 15, 2003 08:23 AM


On the question of the timing of racial group differentiation, it seems to me that we have been overlooking the evidence of Columbus.

Columbus expected to meet Japanese. Yet he had no doubt that the people he met were not Japanese or Chinese. This opinion was held in spite of the fact that he died believing he had found the East Indies not the West Indies.

Today we recognize that those we call American Indians or Native Americans are related to the Old World Mongolian/Chinese peoples but are clearly different. We also know rather accurately the period of separation.

The recent Kennewick Man and Monte Verde findings muddle the dates a bit but main facts are undisputed. Siberian(and possibly Ainu and Eastern Europen)people came to the New World around 11K to 18K YBP. In any case the Siberean/Mongol strain dominated and the ice free corridor closed about 11K YBP. Even those who posit migration by coastal small boats accept that the migrations stopped about ten thousand years ago.

Since that time the Indians in the New World and the similar peoples in the Old World diverged. The cluster of characteristics that mark the classic Han Chinese are therefore less than 10K years old. Included amongst these characteristics of course is intellectual capacity. The widely reported IQs of East Asians and Native Americans diverge by nearly a standard deviation. Even more compelling evidence are the respective affirmative action policies employed. East Asians are discriminated against widely in California lest they dominate the elite schools - especially in math and science. American Indians on the other hand stimulate much different policys.

I assume of course like most today that IQ has a strong genetic component. The natural experiment of the Pleistocene warming has provide us with a clock. One SD in IQ = 10K years.

Posted by: Pat at July 25, 2003 01:35 PM