Another transitional fossil found

[npetreley]

Originally posted by chickenman
no, you're using an out of date definition of evolution, proposed before even the mechanisms of inheritance were understood.

Read: You're using the Darwin's definition which came before people realized that nothing in the fossil record supported it.

Regardless, my response was to the assertion that gradual change was NEVER part of the definition, not that it was NOT A RECENT definition.

Originally posted by RufusAtticus
Sorry, but evolution has never been defined to be gradual

Look! It's a dinosaur! No, it's a bird! It's a plane! No, it's semantic-man!

If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.

...

Independently of our not finding fossil remains of such infinitely numerous connecting links, it may be objected that time cannot have sufficed for so great an amount of organic change, all changes having been effected slowly.

Oh, but it's an easy mistake to make. What the heck did Darwin have to do with defining evolution, anyway?

 

[RufusAtticus]

Originally posted by npetreley
Oh, but it's an easy mistake to make. What the heck did Darwin have to do with defining evolution, anyway?

Sorry, Nick. Darwin is not defining evolution in those quotes. He is describing his theory of evolution. You do understand the difference between a concept and the theory that explains it, don't you?

Did you somehow miss post #57 where I already addressed this?

 

[npetreley]

Originally posted by Sauron

Gould and Eldredge have never formally tied macromutations and saltation with PE. No mechanisms outside of the normal genetic explanations for allopatric speciation were given in their seminal paper on PE. I have yet to see a reference where Gould and Eldredge suggest macromutation or saltation as a mechanism for PE. Gould's paper, "The Return of Hopeful Monsters," has been used as evidence that Gould was proposing saltation as a mechanism for PE. However, the theory of PE is not even mentioned or alluded to in this paper. Rather, the paper is about viewing Goldshmidt's work in a more objective light, and it should be thought of as independent from the PE hypothesis.

It depends on what you mean by "formally". Did they use the word saltation in the description of punk eek? Not directly, as far as I know (although the quote below comes very close). But then why would they? They'd have been laughed off the planet if they did, and they knew it.

And, yes, the column is about defending Goldschmidt's work, not about punk eek. (Though I believe this was actually the issue of Natural History immediately after the issue where Gould first laid out his and Niles Eldredge's punk eek publicly, so one could easily infer a connection, although it was not my purpose to use this quote to do so.)

From "The Return of the Hopeful Monster", Natural History, 1977 (and it IS 1977, not 1997):

I do, however, predict that during the next decade Goldschmidt will be largely vindicated in the world of evolutionary biology.

So if he's not predicting vindication, then I guess it's just a massive coincidence that Gould happened to use all the words "Goldschmidt" "will" "be" "largely" "vindicated" and in that order.

Of course, you'll focus on the word "largely" for the next seven pages in order to do damage control, but that's your MO, so it's to be expected. After all, you're the folks who chastised creationists for failing to understand that when Gould used the word "absence" in "The absence of fossil evidence for intermediary stages between major transitions in organic design", he must have really meant "the illusion of absence of fossil evidence for intermediary stages between major transitions, since there are actually thousands of examples of this absent fossil evidence for intermediary stages between major transitions."

On to saltation...

When people labeled Gould as a saltationist, he said he didn't endorse saltationism, but he was once again just contradicting himself, this time in one sitting! Gould isn't suggesting that saltation never occurs. He is just saying it could occur to a different degree than what Goldschmidt said.

From "Is a new and general theory of evolution emerging?" Paleobiology, January 1980:

I do not refer to the saltational origin of entire new designs, complete in all their complex and integrated features-a fantasy that would be totally anti-Darwinian in denying any creativity to selection and relegating it to the role of eliminating old models. Instead, I envisage a potential saltational origin for the essential features of key adaptations. Why may we not imagine that gill arch bones of an ancestral agnathan moved forward in one step to surround the mouth and form proto-jaws?

Now you'll no doubt want to focus on "potential" in order to do damage control, but hey, there's no escaping that with Gould. Gould left a back door to just about everything he said so that he could contradict himself on a regular basis but do so with seeming impunity.

 

[Sauron]

Originally posted by Jerry Smith
Sauron, the thing is, we will probably never know, short having the actual paper in front of us...

Oh, well, if *that's* all that you need, let me help you. Unfortunately for Nick, I happened to remember that this essay of Gould's was reprinted in The Panda's Thumb , of which I have a well-worn copy. And it does my heart good to type the entire opening section for you, Jerry.

BIG BROTHER, the tyrant of George Orwell's 1984, directed his daily Two Minutes Hate against Emmanuel Goldstein, enemy of the people. When I studied evolutionary biology in graduate school during the mid-1960s, official rebuke and derision focused upon Richard Goldschmidt, a famous geneticist who, we were told, had gone astray. Although 1984 creeps up on us, I trust that the world will not be in Big Brother's grip by then. I do, however, predict that during this decade Goldschmidt will be largely vindicated in the world of evolutionary biology.

Goldschmidt, a Jewish refugee from Hitler's decimation of German science, spent the remainder of his career at Berkeley, where he died in 1958. His views on evolution ran afoul of the great neo-Darwinian synthesis forged during the 1930s and 1940s and continuing today as a reigning, if insecure, orthodoxy.

Contemporary neo-Darwinism is often called the synthetic theory of evolution because it united the theories of population genetics with the classical observations of morphology, systematics, embryology, biogeography, and paleontology.

The core of this synthetic theory restates the two most characteristic assertions of Darwin himself: first, that evolution is a two-stage process (random variation as raw material, natural selection as a directing force); secondly, that evolutionary change is generally slow, steady, gradual and continuous.

Geneticists can study the gradual increase of favored genes within populations of fruit files in laboratory bottles. Naturalists can record the steady replacement of light moths by dark moths as industrial soot blackens the trees of Britain.

Orthodox neo-Darwinians extrapolate these rural transitions in the history of life: by a long series of insensibly graded intermediate steps, birds are linked to reptiles, fish with jaws to their jawless ancestors. Macroevolution (major structural transition) is nothing more than microevolution (flies in bottles) extended. If black moths can displace white moths in a century, then reptiles can become birds in a few million years by the smooth and sequential summation of countless changes. The shift of gene frequencies in local populations is an adequate model for all evolutionary processs -- or so the current orthodoxy states.

The most sophisticated of modern American textbooks for introductory biology expresses its allegiance to the conventional view in this way:

[Can] more extensive evolutionary change, macro-evolution, be explained as an outcome of these micro-evolutionary shifts? Did birds really arise from reptiles by an accumulation of gene substitutions of the kind illustrated by the raspberry eye-color gene?

The answer is that it is entirely plausible, and no one has come up with a better explanation.... The fossil record suggest that macroevolution is indeed gradual, paced at a rate that leads to the conclusion that it is based upon hundreds or thousands of gene substitutions no different in kind from the ones examined in our case histories.

Many evolutionists view strict continuity between micro- and macroevolution as an essential ingredient of Darwinism and a necessary corollary of natural selection. Yet, as I argue in essay 17, Thomas Henry Huxley divided the two issues of natural selection and gradualism and warned Darwin that his strict and unwarranted adherence to gradualism might undermine his entire system. The fossil record with its abrupt transitions offers no support for gradual change, and the principle of natural selection does not require it - selection can operate rapidly. Yet the unnecessary link that Darwin forged became a central
tenet of the synthetic theory.

Goldschmidt raised no objection to the standard accounts of microevolution; he devoted the first half of his major work, The Material Basis of Evolution (Yale University Press, 1940), to gradual and continuous change within species. He broke sharply with the synthetic theory, however, in arguing that new species arise abruptly by discontinuous variation, or macromutation. He admitted that the vast majority of macromutations could only be viewed as disastrous -- these he called "monsters". But, Goldschmidt continued, every once in a while a macromutation might, by sheer good fortune, adapt an organism to a new mode of life, a "hopeful monster" in his terminology. Macroevolution proceed by the rare success of these hopeful monsters, not by accumulation of of small changes within populations.

I want to argue that defenders of the synthetic theory made a caricature of Goldschmidt's ideas in establishing their whipping boy. I shall not defend everything Goldschmidt said; indeed, I disagree fundamentally with his claim that abrupt macroevolution discredits Darwinism. For Goldschmidt also failed to heed Huxley's warning that the essence of Darwinism -- the control of evolution by natural selection -- does not require a belief in gradual change.

As a Darwinian, I wish to defend Goldschmidt's postulate that macroevolution is not simply microevolution extrapolated, and that major structural transitions can occur rapidly without a smooth series of intermediate stages. I shall proceed by discussing three questions: (1) can a reasonable story of continuous change be constructed for all macroevolutionary events? (my answer shall be no); (2) are theories of abrupt change inherently anti-Darwinian? (I shall argue that some are and some aren't); (3) do Goldschmidt's hopeful monsters represent the archetype of apostasy from Darwinism, as his critics have long maintained? (my answer, again, shall be no).

All paleontologists know that the fossil record contains preicoius little in the way of intermediate forms; transitions between major groups are characteristically abrupt. Gradualists usually extract themselves from this dilemma by invoking the extreme imperfection of the fossil record -- if only one step in a thousand survives as a fossil, geology will not record continuous change. Although I reject this argument (for reasons discussed in essay 17), let us grant the traditional escape and ask a different question. Even though I have no direct evidence for smooth transitions, can we invent a reason sequence of intermediate forms -- that is, viable funtioning organisms -- between ancestors and descendants in major strctural transitions? Of what possible use are the imperfect incipient stages of useful structures? What good is half a jaw or half a wing? The concept of preadaptation provides the conventioa answre by permitting us to argue that incipient stages performed different functions. The half jaw worked perfectly well as a series of gillsupporting bones; the half wing may have trapped prey or controlled body temperature. I regard preadaptation as important, even an indispensable, concept. But a plausible story is not necessarily true. I do not doubt that preadaptation can save gradualism in some cases but does it permit us to invent a tale of continuity in most or all cases? I submit, although it may only reflect my lack of imagination, that the answer is no, and I invoke two recently supported cases of discontinuous change in my defense.

[excerpted the two examples for brevity's sake]

[...]

If we must accept many cases of discontinuous transition in macroevolution, does Darwinism collapse to survive only as a theory of minor adaptive change within species? The essence of Darwinism lies in a single phrase: natural selection is the major creative force of evolutionary change. No one denies that natural selection will play a negative role in eliminating the unfit. Darwinian theories require that it create the fit as well. Selection must do this by building adaptations in a series of steps, preserving at each stage the advantageous part in a random spectrum of genetic variability. Selection must superintend the process of creation, not just toss out the misfits after some other force suddenly produces a new species, fully formed in pristine perfection.

We can well imagine such a non-Darwinian theory of discontinuous change -- profound and abrupt genetic alteration luckly (now and then) making a new species all at once. Hugo de Vries, the famous Dutch botanist, supported such a theory early in this century. But these notions seem to present insuperable difficulties. With whom shall Athena born from Zeus' brow mate? All her relatives are members of another species. What is the chance, of producing Athena in the first place, rather than a deformed monster? Major disruptions of entire genetic systems do not produce favored -- or even viable -- creatures.

But all theories of discontinuous change are not anti-Darwinian, as Huxley pointed out nearly 120 years ago. Suppose that a discontinuous change in adult form arises from a small genetic alteration. Problems of discordance with other members of the species do not arise, and the large, favorable variant can spread through a population in Darwinian fashion. Supose also that this large change does not produce a perfected form all at once, but rather serves as a "key" adaptation to shift its possessor toward a new mode of life. Continued success in this new mode may require a large set of collateral alterations, morphological and behavioral; these may arise by a more traditional, gradual route once the key adaptation forces a profound shift in selective pressures.

Defenders of the modern synthesis have cast Goldschmidt as Goldstein by linking his catchy phrase -- hopeful monster -- to non-Darwinian notions of immediate pefection by profound genetic change. But this is not entirely what Goldschmidt maintained. In fact, one of his mechanisms for discontinuity in adult forms relied upon a notion of small underlying genetic change. Goldschmidt was a student of embryonic development. He spent most of his early career studying geographic variation in the gypsy moth, Lymantria dispar. He found that large differences in the color patterns of caterpillars resulted from small changes in the timing of development: the effects of a slight delay or enhancement of pigmentation early in growth increased through ontogeny and led to profound differences among fully grown caterpillars.

[Discussion of Goldscmidt's "rate genes" excerpted]

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. Prolong the high prenatal rate of brain growth into early childhood and a monkey's brain moves toward human size. Delay the onset of metamorphosis and the axolotl of Lake Xochimilco reproduces as a tadpole with gills and never transforms into a salamander. (See my book Ontogeny and Phylogeny, {Harvard University Press, 1977} for a compendium of examples, and pardon me for the unabashed plug.) As Long argues for the external cheek pouch: "A genetically controlled developmental inversion of the cheek pouch may have occurred, recurred, and persisted in some populations. Such a morphological change would have been drastic in effect, turning the pockets 'wrong side out (furry side in), but nevertheless it would be a rather simple embryonic change.

[remainder deleted for brevity]

 

[npetreley]

Thanks!! I especially like this part in that chapter (yes, I knew it was republished in Panda's Thumb, though I assume it was edited and expanded (that's perfectly normal):

The half jaw worked perfectly well as a series of gill supporting bones; the half wing may have trapped prey or controlled body temperature. I regard preadaptation as important, even an indispensable, concept. But a plausible story is not necessarily true.

I'd correct him here. Most explanations for evolution aren't necessarily plausible, either. Indeed, the whole reason for writing this book is the fact that evolutionists couldn't come up with a plausible explanation for the fossil record.

I do not doubt that preadaptation can save gradualism in some cases but does it permit us to invent a tale of continuity in most or all cases?

Most evolutionists seem to think so. You certainly thought the goal of saving evolution permitted you to invent a tale of punk eek.

I submit, although it may only reflect my lack of imagination,

Nice to see you admit that's where these things come from.

that the answer is no, and I invoke two recently supported cases of discontinuous change in my defense.

And you left them out for brevity....you sure you don't want to type those in?

 

[Jerry Smith]

Sauron,

Thanks for taking the time to type all of that in from your copy of Panda's Thumb. That must have been quite a lot of work for you, and I do appreciate it. I think we can all see the points being made.

Nick,

I am a lover of irony, even when its victim. The irony is in the person to whom I must address this next statement:
You were correct in your assertion that Gould predicted in 1977 that Goldschmidt would be vindicated in the next decade. I did not check the original article, but I have found that it is quoted the same way in other places, from both sides of the debate, so I have little reason to suspect there was any subtle deception there. Thank you for backing up one of your claims.

 

[HtH]

I understand the concept, but I find it interesting that you state it in such definite terms, as if you know this is how things worked. The only reason Punk Eek exists is because people like Gould couldn't come up with another way to explain the fossil record. The problem with Punk Eek and every other theory incorporating eovlution is that there's no actual evidence that selection pressure can result in bacteria-to-kangaroo evolution AT ALL, regardless of whether you prefer to see evolution as a continuous gradual process (which is how it was first defined) or a series of spurts due to increased selection pressure.

I will continue to awknowledge evolution as the correct theory as long as it remains more probable, and logical, than creationism.

And I said that I agreed that punctuated equilibrium was a load of codswallop, taken in the most extreme form. I don't see what you've got against gradualism, though. Of course there can be no direct evidence of gradual evolution, just as there can be no direct evidence for creation. However, the circumstantial evidence for evolution is so enormous that it is the only viable (for me) theory.
Ta,
HtH