Tharmas

Exaggeration acknowledged! I take it back...

deddogg

Thanks guys for all your help and useful information.

Oolon, great summary I appreciate the effort! Could you expound upon Ethology and palaeontology? I generally assumed that palaeontology was never on a microscopic or smaller level, but only like Indiana Jones or what have you. Is this correct? And does Ethology examine only living things, including microscopic? I would just appreciate more elaboration on those topics if possible.

Liquid, could you also elaborate on the straw-man fallacy you spoke of? Is that really even effective? I am just unfamiliar and curious about it. Also, these two schools of thought seem pretty different to me. Can you also refine your point on how they are non-contradictory? I understand that you said they happen at different times, is there an explanation about this? Could you provide a link perhaps to this debate between which is more important?

I know these are probably huge subjects to discuss but I would really enjoy that, I am looking to soak up as much information as possible. Thanks!

bd-from-kg

A few corrections and some comments.

To the best of my knowledge, Gould is not a paleontologist. He studies snails. Not snail fossils, but real live snails. Of course his main interest how natural selection works in snail populations.

Not so. In the first place, the changes involved in “punctuated equilibrium” are pretty small relative to the broad patterns of evolution. The main point of PE is that (unlike “classical” Darwinism) it is consistent with the observation that most species show remarkable stability over their lifetimes. Instead of seeing one species change gradually into another, what we typically see is a new species appearing “suddenly” in the record, often (but not always) accompanied by a “sudden” demise of a closely related species.

However, by “sudden” Gould (and Eldridge) mean a process that is nearly instantaneous in terms of the geological time scale, which means that it takes only a few thousand years. A process of such a “short” duration cannot be distinguished from a truly instantaneous event in the fossil record.

Not only does the fossil record show a degree of stability within species that seems incompatible with “classical” Darwinism, but there are very good reasons why such stability should be expected, which had been worked out by Mayr and others. It can be shown statistically that there is a very strong tendency for any significant change in the genome of species with a large number of interbreeding individuals to be suppressed; i.e., new mutations have very little chance of establishing themselves, even if they’re beneficial. To get significant change, a relatively small group has to become reproductively isolated from the larger group (or the number of surviving individuals has to become very small for some reason). At that point the chances that a favorable mutation can establish itself in the population become significant, and evolution can proceed in just the way Darwin envisioned, through random mutation and natural selection.

None of this is all that revolutionary, and it certainly doesn’t involve any “new laws of nature”. It also should be emphasized that, even with PE, evolutionary change still looks pretty gradual on a larger scale. Most new species are very similar to the species they evolved from. the only “jumps” in the PE theory are from one species to an immediate successor, and even these “jumps” take quite a while in human terms.

liquid

It's simple. Many creationists will state that as there is both punctuated equilibrium supporters, and gradualism supporters, evolutionists don't know what they are going on about and are probably totally wrong and messed up.

It's wrong for all sorts of reasons, but basically it is perfectly possible for both to happen. Some grad, then some punkeek might happen in chronological succession, or some grad might happen in one area and punkeek in another simultaneously, geographic seperation being key. Of course, one is bound to be a dominant trend, but the argument is over which one and by how much.

Then of course, just because there is disagreement, and not even considering the fact that the disagreement is not really fundamental, it doesn't invalidate the whole field of evolution as creationists would hope. The fact is that scientists DO disagree, and resolve the disagreements on the basis of evidence, something creationists don't do.


It's not a good argument, but you will get the odd Hovindkiddie cut and pasting it.

They are in disagreement, but are not inherently contradictory. They are different, but not by necessity. You might get one person who is 99% grad, 1% punkeek, so to speak, or 25/75, or any point along the scale. It's only as different as the extremity of the views of the people arguing. One view will come to prevail, but we don't know which yet. Probably most people will accept gradualism but understand that there are periods of evolutionary equilibrium or rapidity. It's not a great insight, and you only have to look at shark morphology for evidence of status, and the cambrian explosion for evidence of rapidity.

To give an analogy, the argument is whether the accelerator pedal gets pushed hard and jerkily, or gradually and held.

Deal with thie later, got to go.

bluefugue

bd from kg:

Have you read the chapter "puncturing punctuationism" in Dawkins' book The Blind Watchmaker? I lack the expertise to have my own opinion in this matter but I will parrot the point Dawkins makes in that chapter, which is that there is nothing in Punk Eek that is truly incompatible with "classical" Darwinism, unless you start with a caricature of gradualism that assumes a constant rate of change -- which, according to Dawkins, few if any Darwinists ever actually suggested was the case. The Punk Eek model suggests longer periods of stasis and shorter periods of change, but, unless it is a theory of saltationism (i.e. large, complex morphological changes coming about as a result of a single mutation, or a very few mutations), it must still be essentially "gradualist." It's just that the gradual change does not occur at a constant rate -- which, again, it is not clear that classical Darwinists ever claimed was the case anyway.

Personally I am a bit unclear on Gould's own views toward saltationism (Dawkins takes a dim view of it, arguing that it is too improbable for large mutations to be anything but lethal). In the essay "Return of the Hopeful Monster" in The Panda's Thumb, Gould says:

Now obviously this essay is 20 years old and so hardly represents the state of the art on this discussion. But it sounds as if Gould is accusing Darwinists of caricaturing saltationism, much as Dawkins accuses Gould of caricaturing gradualism. Gould's appeal to embryology is a novel way to approach the question, and I must confess I hadn't thought of it before. It still seems to me you can only get so far with that route, though. Maybe you can get "more" or "less" of an existing structure, resulting in a large morphological change, with only small mutations leading to timing-changes in the embryological stage. Thus maybe you could in fact get large morphological differences as a result of a single mutation. But to get a truly new structure, it still seems to me that Dawkins' point holds, that such a structure must be gradually shaped by natural selection over a scale that requires many small mutations and many generations (but not necessarily a constant rate of change, and not necessarily a period of time that is large on the geologic scale -- perhaps a few tens of thousands of years could suffice in some cases). To take it to the extreme, you are not going to get a working vertebrate eye in a single mutation -- that would be fantastically improbable, as Gould and Dawkins would surely both agree. (The exception would be Dawkins' "stretched DC-10" style of mutation, in which a pre-existing part is simply copied for another part of the body, i.e. a centipede with 99 segments having offspring with 100 segments -- but I mean a vertebrate eye springing whole-cloth out of a genome that had no eye at all a generation before.)

I sometimes wonder whether this whole debate just comes down to semantics, to an inability of people to agree on precisely what they mean by "gradual."

[ February 12, 2002: Message edited by: IesusDomini ]</p>

tronvillain

bd-fromkg: To the best of my knowledge, Gould is a paleontologist. He is currently Curator in the Department of Invertebrate Paleontology at the Museum of Comparative Zoology at <a href="http://www.mcz.harvard.edu/Departments/InvertPaleo/personnel_2.htm" target="_blank">Harvard</a>. Have a look at this brief <a href="http://prelectur.stanford.edu/lecturers/gould/" target="_blank">biography</a>. Now, I defy you to show me anything that says he studies "real live snails."

Anyway, Talk.Origins has a few things to say about <a href="http://www.talkorigins.org/faqs/punc-eq.html" target="_blank">Punctuated Equilibrium</a>.

From The Origin of Species (by way of Darwins Dangerous Idea):

Quetzal

Deddogg: I’d like to add a bit more information to the differences of opinion between Gould, Eldridge (who’s the paleontologist in this scenario), Lewontin et al on the one hand and Dawkins, Maynard-Smith, Dennett et al on the other. I mean besides the obvious personality conflicts .

In the first place, as has been pointed out, both sets firmly agree that natural selection operating on phenotypes of individual organisms is the main cause of evolution. However, Gould is a proponent of the idea that there are phenomena that occur at higher levels of complexity. F’rinstance, Gould has proposed a theory of species sorting whereby, just as some individual organisms are more likely to survive, some species are more likely to survive than others. He claims that certain evolutionary lines give rise to more new species than others. More than PE, this idea drives neo-Darwinian “purists” like Dawkins nutso.

Another area of contention is Gould’s complexity theories, especially his anti-reductionist stance (aka evolutionary pluralism). An example would be an ant colony. Your individual ant is a pretty simple critter. It doesn’t have a really huge repertoire of behaviors, and ants can only signal each other in about a half dozen ways. However, an ant colony exhibits extremely complex behaviors taken as a whole. Some species enslave other insects, some farm fungus, some maintain “domesticated” aphid colonies. These behaviors only come about when large numbers of ants interact. In other words, Gould uses this type of “emergent property” as evidence for his claim that evolving species also exhibit such emergent properties. Gould postulates that there are complex patterns in nature that natural selection alone can’t explain. He’s basically looking for the “why’s” such as: why are there 500 species of beetles, but only 50 species of priapulid worms? Why doesn’t most DNA do anything (and hence could not be the result of natural selection)? Why did the dinosaurs die out at the end of the Cretaceous, but the mammals survived? Gould claims that natural selection can only explain individual adaptations, not long-term evolutionary trends.

A final, and probably most important area of contention, is Gould’s idea of “spandrels” or exaptations (a term he coined to identify non-adaptive structures or changes in an organism) in biology. Gould points out that many organisms have traits that were not the result of natural selection. These traits exist because they are sort of a by-product of something else. The presence or absence of these exaptations have absolutely no bearing on the fitness or survival of an organism. One example is the human ability to read and write. Natural selection caused human brains to become big (in relation to body mass) for reasons to do with survival. Once they became big, they enabled us to do lots of things that had nothing at all to do with the reason natural selection created them in the first place, e.g., read and write. This doesn’t, of course, mean that these exaptations are useless – they are very likely the things that would increase the fitness of an organism for other environments or conditions, or that would allow the organism to take advantage of a new opportunity. In this case, the exaptations will be acted upon by natural selection, and change into adaptations in their own right.

Does that confuse the issue enough?

tronvillain

While totally unrelated, <a href="http://www.cancerguide.org/median_not_msg.html" target="_blank">this</a> is a very interesting essay by Gould on statistics and cancer.

Oolon Colluphid

Sorry, I realise now that what I wrote could be misconstrued. I was referring to Gould getting attacked in general, not spandrels in particular. This is what happens when one writes off the top of head while at work! Blimey we’re a nitpicky lot (and quite right too ). It’s a few years since I read Darwin’s Dangerous Idea, but I remember Gould getting quite a pasting.

I think the ‘problem’ is not with the spandrel / exaption idea itself, it is with Gould blowing up into some radically profound insight something which most biologists took for granted: that body parts and systems could take on novel functions unrelated to their previous ones. Nobody ever doubted that ancient fish fins became legs, for instance. Yet I read (in a SciAm article, circa 1997, I didn’t keep it ) him make the statement “what use is 5% of a wing?” His point was it may not have originally been used for flight, but rather, it became exapted for flight from something else. Well duh. Yeah, from theropod forelimbs. Sorry if I’m underwhelmed. I’ve never forgiven him that, partly because it’s straight out of the cretinist list of evo-stumpers (and he should bloody well know better), and partly because of the obvious Dawkinsian (from back in 1986!) retort: ‘it’s precisely 1% better than a 4% wing in breaking your fall rather than your neck if you fall out of a tree’. Maybe it’s right, maybe not. What it is is, making a big fuss about not very much, something either banal or irrelevant.

Ref sources, the best place I know of to start is the Gould Files I linked above.

Cheers, Oolon

PS I love the way Gould writes, but I find the side issues he uses to make his points are often more interesting than the points themselves.

Oolon Colluphid

A quick search at the marvellous <a href="http://dogbert.abebooks.com/abe/BookSearch" target="_blank">abebooks</a> shows that you can pick up a second hand copy starting from $4.50.

Cheers, Oolon