Convergence?

[Josh]

Originally posted 6/23/06:

I contribute to Dr. Hugh Ross' organization Reasons to Believe (www.reasons.org) and so receive a CD each month on science/ faith related issues.

In a recent discussion on evidences against naturalistic evolution, Ross and his team members brought up what scientists call Convergence.

This is where completely unrelated (at least from a common ancestry perspective) species have 'evolved' exactly or nearly exactly the same physical capacities (even down to the chemical and cellular levels) or behavioral traits.

For instance, there are two kinds of bats: those who echo- locate to move and find food (mircobats, I think, they said), and those who use sharp eyesight (megabats, I believe). According to the naturalist paradigm, these two groups separated long ago. But interestingly, there is a sub group of the megabats (I can't remember the technical terms) bats that has subsequently (again, according to the naturalist paradigm)developed echo-location all on their own- an echo-location identical to the other species.

But one of the tenets of naturalistic evolution (especially according to Stephen Jay Gould) is that evolution is blind and unguided, the result of unpredictable factors, so that if we could rewind the clock and start evolution over at some past point, we would find ourselves with completely different outcomes- ie, evolution this complex (echo-location) doesn't happen the same way twice on its own. Of course, the same environmental factors could, theoretically, result in somewhat similar general changes, but it is the complexity of many examples of convergence that causes one to doubt unguided, naturalistic evolutionary mechanisms.

There are, reportedly, 100s of examples of convergence. Another notable one was the social behavior of ants, termites, and bees. Each of these insect groups have, according to naturalist evolution, developed virtually identical social behaviors, though they are completely unrelated.

See the link below, as I've only scratched the surface and may have butchered it in the process:

www.reasons.org/resources/fff/2000issue04/index.shtml#convergence_evidence_for_a_single_creator

[hume]

Originally posted 6/25/06:

The article in your link states, "Evolutionists assert that convergence results when unrelated organisms encounter nearly identical selection forces (environmental, competitive, and predatory pressures). Natural selection then channels the random variations believed to be responsible for evolutionary change along similar pathways."

So far, so good. The author continues, "If evolution is indeed responsible for the diversity of life, one would expect convergence to be extremely rare. The mechanism that drives the evolutionary process consists of a large number of unpredictable, chance events that occur one after another. Given this mechanism and the complexity and fine-tuning of biological systems, it seems improbable that disparate evolutionary pathways would ever lead to the same biological feature."

Thus far the writer's not offering much of an argument. He's just stating, "I find this to be improbable."

He then cites as support "two ... studies that, from an evolutionary perspective, [require] echolocation in bats to have evolved independently in two separate groups (microchiroptera and megachiroptera) ... Previous analyses also indicate that the strikingly similar limb structures of bats and flying lemurs used for flying, likewise, must have evolved independently."

So, first we have distinct bat groups evolving echolocation. Bats, unlike (most? all?) birds, are strictly nocturnal. Their common "challenge" is to find an effective way to fly & navigate in pitch darkness. Is it surprising that echolocation turns out to be an excellent solution, in more than one case?

As for bats and flying lemurs having similar flight limb structures: what else do bats & lemurs have in common? Both are mammals, not birds. They have (in evolutionary terms) a much more recent common ancestry than any mammal has with any bird. This entails that, when it came to the possibility of flight, they were starting with basically the same (mammalian, not avian) features. Again, is it surprising that similar starting conditions and similar challenges resulted in similar outcomes?

The writer's next example: "the brain structure of hummingbirds, songbirds, and parrots responsible for vocal learning ... is essentially identical. This is surprising, since these three birds are unrelated to one another." Maybe less surprising than the author contends, since "related" means something rather different to an evolutionist, for whom all birds are in a fundamental sense related. These 3 species of birds have a common ancestor who would not have been dramatically different from any one of them; given their literally identical starting point, the notion that the 3 ensuing branches of the evolutionary "bird tree" would include similar solutions to similar problems is so far from surprising or unlikely that it is, on the contrary, quite expected.

Nevertheless, the author concludes from the above examples that, "It is difficult to accept, even when biased towards naturalism, that the[se] complex structures ... could have emerged strictly through random events." I simply disagree; from the "naturalistic bias," this is not only not difficult to accept, it's very much along the lines of what one would expect.

In a more general sense, as creationists are fond of pointing out in a different context (namely the arguments in favor of the "anthropic principle"), our world is a very specific place with a large number of carefully defined phsyical and chemical variables that constrict the possible biological solutions to any given challenge. It's not as if natural selection is working with a vast blank slate of possibilities. Again, this makes it hardly surprising that we'd find examples of different organisms ending up with very similar solutions to similar problems.

[Josh]

Originally posted 6/26/06:

Great points- good critique. A few thoughts:

Again, note the apparent contradiction in the first two quotes from the article:

"Evolutionists assert that convergence results when unrelated organisms encounter nearly identical selection forces (environmental, competitive, and predatory pressures). Natural selection then channels the random variations believed to be responsible for evolutionary change along similar pathways."

"If evolution is indeed responsible for the diversity of life, one would expect convergence to be extremely rare. The mechanism that drives the evolutionary process consists of a large number of unpredictable, chance events that occur one after another. Given this mechanism and the complexity and fine-tuning of biological systems, it seems improbable that disparate evolutionary pathways would ever lead to the same biological feature."

Upon further investigation, I think part of what's going on here is that paragraph #1 (with its focus on specific natural selection forces) describes mainstream evolutionary theory, whereas paragraph #2 (with its focus on unpredicable, chance events) is actually indicative of Stephen Jay Gould's brand of evolutionary theory. Gould downplayed natural selection and trumpeted mutation and historical contingency, propelling the term "punctuated equilibrium" into the evolutionary vocab (See wikipedia under Steven Jay Gould to see this borne out).

It appears to me that the author of this article (Rana), is trying to use the convergence evidence against the Gouldian spectrum of evolution, but simplistically lumps all evolutionary theory into Gould's "historical contingency".

These examples of convergence do challenge random mutation, perhaps, much more than some calculated mechanism of natural selection. But what's missing is a full-orbed consideration of various evolutionary responses to the issue of convergence.

One more point and one more question:

The point would be, where indeed is the much anticpated 'mechanism' of macroevolution? There isn't a workable model? Is it just a matter of time, or is it so complicated that we shouldn't expect one any time soon? What can be said of evolutionary theory when all the proposed mechanisms so far have been found to be dead ends? If I'm guilty of hyperbole here, please correct me.

And a question about convergence, for you specifically, Hume:

How complex and similar would two 'unrelated' biological (or behavioral, but let's not focus on that just now) systems or organ structures in an organism have to be for you to think that there was no possibility of a strictly naturalistic explanation?
Also, how 'unrelated' would such organisms have to be?

Just an extreme example: If planet earth and planet Mars had roughly the same ecosystems and it was found that an almost identical species of gorilla existed on both planets, would you in that case presume something other than it was simply the result of similar natural selection forces?

If yes, then pare the example down to something more realistic. I'm just curious at what point "improbable" would raise your eyebrows.

[hume]

Originally posted 6/28/06:

The Martian gorillas would be extraordinarily unlikely because they would have developed in a completely independent system with essentially no history in common with ours. So yes, the existence of Martian gorillas might rise to the level of a counter-example against evolution (certainly "blind, unguided" evolution). But of course, this is only a thought experiment. It doesn't do anything for the convergence argument, other than demonstrate that impossible cases of convergence are not logically ruled out (though, like so many imaginary constructs, they may very well be ruled out in practice. I note that, to date, there's been no *solid* evidence of gorillas on Mars. No bananas either.).

Obviously, convergence examples like echolocation in bats aren't of this magnitude -- not even close. The list of attributes, genetic codes and environmental pressures common to 2 bat species would be as long as your arm. The list common to the Martian and Terrestrial gorillas would be: nothing. For that matter, this thought experiment may be said to bolster the evolutionist's position by helping to place terrestrial convergence into perspective.


You write, "where indeed is the much anticipated 'mechanism' of macroevolution? ... Is it just a matter of time, or is it so complicated that we shouldn't expect one any time soon? What can be said of evolutionary theory when all the proposed mechanisms so far have been found to be dead ends?" I'm not sure what to say -- it's news to me that "the proposed evolutionary mechanisms" have come to dead ends.

Fundamentally, we're coming at this from different starting points. I don't envision evolution as a sketchy, questionable theory; on the contrary, it seems to me, broadly speaking, both well-evidenced and plausible. It's an interesting measure of the gulf separating "creationism" and "evolutionism" that what you take to be evidence against evolution, I take to be evidence in its favor (e.g., is convergence a "problem" or a predicted outcome?). Not sure how much headway we can make on that.


A substantial part of the difficulty faced by Darwin's theory has nothing to do with data or studies or contrary evidence. It's simply the fact that our minds don't easily encompass time periods of more than a century or two. To us, species seem fixed and defined, because in our lifespans they certainly are. In 10 times our lifespans they're still pretty stable. The idea that species can transform into other kinds of creatures is inherently implausible to us, and it always will be.

Look, geology has the same problem: it's a stretch for us to imagine that Mount Hood was once a bit of rolling grassland, which formed over millions of years into the 11,000 foot peak we see today. Even believing this to be so, we surely don't think of Mt. Hood as a sort of fleeting temporary object. Well, life is much older than mountains; even some individual species are "older than the hills." (If you're ever in Hawaii and someone mentions the tiger sharks, consider that Mauna Kea is said to be about 1 million years old; there are shark fossils from 300 million years ago.).

If we can handle the mutubility of mountains, why not the mutability of species? (I'm not sure; part of the answer is that we really can't handle either. We don't often reflect on mountains in that way -- in general, we really do think of them as utterly permanent structures.)

[Josh]

Originally posted 6/28/06:

A couple things:

1. Impossible Cases?

"impossible cases of convergence are not logically ruled out"

Help me with this phrase. If I'm reading you right, is this a variation on the "if it exists, it must not be impossible for it to exist" proposition, or something entirely different?

(it's sounding like a logicians phrase, but I can't decipher it)

2. Pigs in Space:

The point of the gorillas exercise (perhaps I should have used pigs), in my mind, was to imagine an extreme case of convergence, one which, if it was discovered, would lead the researcher beyond naturalist conclusions: ie, the gorillas were placed there by extra terrestrial life, or something like that. In finding some potential agreement that such a fanciful example would lead us away from a purely naturalist conclusion, I had hoped that we could pare down the example to arrive at the answer to the question: at what point, in your mind, would the complexity of a case of convergence seem to great to be explained naturalistically?

It seems to me that we can't just say no matter how complex it is, it *must* be explained as the result of random, environmental (and other naturalistic) factors. Mightn't we employ mathematical probability to set some boundaries here? (well, not us, specifically, my schedule's a bit full just now, but...)

3. Gulf War Vets:

The gulf is quite great between most "creationists" and "evolutionists", but don't presume the gulf is that great for us. The benefit we have is familiarity with both sides- and some degree of personal identification with both paradigms.

I must say, honestly, that I don't have much of a prejudice against evolutionary theory (or naturalism in general) left. I grew up under the shadow of both ends of the natural/ supernatural spectrum, so it's not too hard to "think" from either perspective.
I don't think I personally have had an a priori opinion that evolutionary theory is a "sketchy, questionable theory". I'll start a new thread regarding my questions about the "mechanism" of evolutionary theory, so I can explain myself more fully.

Also, I'm not as 'vested' in the outcome of such dialogues as some might be, which I'm finding quite refreshing. Speaking of headway, I'm making quite a bit lately, so there's no reason to doutt that will continue (heh).

Of course, there is another gulf: I'm somewhat of a late bloomer in science and math, but I'm making headway there too.

4. Making a Mole out of a Mountain?

It may be a stretch for us to 'envision' the events of geological history, but it's not hard to 'explain' them scientifically in a way that will find little debate.

It's the complexity of biological evolution (and the sketchy nature of any of the explanations made of it so far) that lands this debate in another camp, I think.

Beside being a good admonition to humility, your geology analogy does well to show how small, incremental changes can produce massive changes eventually. But non-living geological features behave enormously differently than the biological history of life- producing random but predictable changes, but never increasing in complexity and constantly reverting to the norm. Couldn't we turn the tables and say that this stasis we see in geology is also what we should expect in biological systems?

[Josh]

Originally posted 6/28/06:

Responses to your points:

1. "Impossible Cases":

That was poorly put, especially the use of "impossible." Slightly less confusing would be:

"cases of convergence which would challenge evolution are not logically ruled out."

Anyway, the point is that

A. your gorillas provide an example of convergence so implausible that, if they existed, evolution would be hard-pressed to account for them.

B. your gorillas don't exist, so as far as that goes they aren't a real challenge.

C. however (and this is the "logical" issue) they can still demonstrate something, even tho they don't exist. What they demonstrate is simply that we can conceive of them; they are not logically absurd constructs (they are not like square circles). Therefore (given #1 above) it's not possible for the evolutionist to counter that there is absolutely no conceivable scenario in which convergence would challenge the theory. (Not that evolutionists would counter in this way, nor that they need to.)

But the real point was that all of this is fairly trivial; the gorillas aren't demonstrating much, if that's all it amounts to.

2. "Pigs in Space"

"at what point, in your mind, would the complexity of a case of convergence seem to great to be explained naturalistically?"

Hmm. I guess there's no substitute for "getting down to brass tacks": I'd need to see examples -- the ones given so far don't rise to that level.

It's not only an issue of complexity, but also of history. For instance, Haldane's Rabbit would do the trick: to quote one of your guys (Dembski):

"The evolutionist J.B.S. Haldane, when asked what would convince him that evolution was false, replied that finding a rabbit fossil in pre-Cambrian rocks would do quite nicely. Such a fossil would, by standard geological dating, be out of sequence by several hundreds of millions of years."

Dembski goes on to posit that Haldane was mistaken, because an evolutionist would deal with Pre-Cambrian rabbits by envoking convergence (hey, rabbits happen). This is a howler (and doesn't say much for Dembski's understanding of basic geology); the Pre-Cambrian era (from 3.9 billion years ago to 543 million y.a.) emcompasses the rise of the very earliest & most basic life forms. Haldane was saying, "show me a rabbit frolicking in the vast poisonous oceans, breathing the methane air, munching on masses of algae and bacteria instead of carrots; that would do quite nicely."

So yeah, one of those fossil rabbits would do the trick. Of course Haldane was doing more than giving a glib answer. He was alluding to the fact that life's history unfolds in this clear development from rudimentary beginnings to increasing diversity and complexity. This is not so easy to explain in classic Creationist models: why is God "taking his time" like this? Why create a species of bacteria, then some algae, then sort of cool your heels for another billion (yes billion) years (yes years), gradually adding in an algae here, a bacteria there ... finally, 2+ billion years after kicking this off, get down to the whole "animal and plant" project as we know it. If God wasn't creating by way of a system of evolution, then what was going on here?

4. "Stasis"

(Our use of the term "evolution" to describe Darwin's mechanism brings in a misleading connotation here.)

There does not seem to be any inherent "complexifying" or "advancing" tendency in evolution by natural selection per se (this was a pet peeve of Gould's) -- responding to the environment can result in any number of scenarios. A highly stable environment doesn't encourage any change at all in a species already well-adapted to it. A species in this kind of stasis *is* "evolving" -- natural selection is actively encouraging the species to remain roughly as it is. Other environmental pressures favor simplification or degredation of complex features (e.g., loss of eyesight among most cave-dwelling critters).

So why has our ecosystem continually increased in complexity over time? Not because of evolution per se -- evolution in this sense is nothing more than a mechanism; it works with whatever's there at the time. Looking back in earth's history, we see evolution first at work on hardly anything -- a tiny bit of chemical material, a couple rudimentary organisms, what have you. Those tiny creatures were faced with an entire planet to colonize, a whole world as yet unclaimed by life. In subsequent years life has claimed it, and so naturally there are many more creatures around today than in the early years. (Living creatures reproduce; populations expand. If you start with hardly any, you'll probably get alot more over time. That, again, is not due to the direct effects of evolution.)

Life claimed the earth, and in the process utterly transformed it. Keep in mind that animals (cyanobacteria) created our atmosphere. And much of what we now know as life subsists by eating other creatures (whether plants or animals); again, this entire food source developed over time as life expanded. Land plants dramatically changed the environment when they appeared. It's recursive: life alters its own environment, thus requiring living things to adjust to that new environment, which once again alters the environment ...

The fact that life has expanded and diversified is primarily a matter of history, not evolution. Of course evolution was intimately involved in shaping that history, but it had nothing to do with the historical fact that earth started out as a big empty rock.

[Josh]

Originally posted 6/28/06:

OK, enough with the apes. My hope was that some criterion for judging whether a case of convergence was too complex (or perhaps statistically improbable) to be explained by naturalism, or not, might be siphoned out of the process- starting with an obvious case, and winnowing the example. But I fear my planet of the apes is dead in the water... or gone with the water, seeing as it was Mars after all.

[Josh]

Originally posted 6/28/06:

I'm willing to see Dembski's remark about the rabbit as tongue-in-cheek, simply making the very accurate point that naturalism will always assume naturalism over supernatural causes, prefering no explanation over a supernatural one. Conversely, ID ers or creationists are seen as inserting a "God of the gaps" whenever something in science is currently unexplainable. And on it goes...

But Haldane's rabbit is like my Martian gorillas... or worse. Finding a rabbit in pre-cambrian strata wouldn't just challenge evolutionary theory- it would challenge all of physics. To suppose that it would take something that extreme (and only that extreme) to falsify evolutionary theory is ludicrous. Good theories are falsifiable; surely good theories also try to establish realistic falsification tests.

"Life's history unfolds in this clear development from rudimentary beginnings to increasing diversity and complexity"

That's just it- that's an old assumption of evolutionary theory that has undergone significant adjustment in the last 30 years. The discovery of a mulitiplicity of near total extinction events in life's history, followed immediately by the emergence of new species (even whole phyla), followed by stasis, ended by another catastrophe, makes "life's history" much more complicated than such a summary.

Such discoveries are the reason evolutionary theory has shifted from a focus on gradualism (relying heavily on the natural selection mechanism) to other 'mechanisms' such as punctuated equilibrium (not really a 'mechanism' at all, much more a stop-gap, severely sketchy hypothesis).

[Josh]

Originally posted 6/29/06:

You're helping me get a better handle on Gould's idea of 'historical contingency'. This interplay between the environment and living organisms is crucial. But, speaking of non-biological factors and their influence on evolution brings us dangerously close to a discussion of the 'anthropic principle' and whether it's really got any weight as an argument for the ID camp.

For another day, my friend. It's been good so far. I hope I haven't wearied you. I think this has been quite beneficial, myself. Hopefully others will agree.... someday, if someone bothers to read this thread. (heh)

[Josh]

Originally posted 6/28/06:

I'll grant you an overall shift from 'rudimentary' to 'complex', of course. If one grants the 5 billion year age of the earth (as I certainly do), but one also thinks that God was frequently active as a causal, creative agent through the history of biological life, then one must certainly ask your question- why was God 'taking His time'?

I think there are some good answers to that, but I'm not necessarily sure that having a Creator God kick off naturalistic evolution answers the question any better- either way, a tremendous amount of time is elapsing between the original creation and the climax of the Christian story.

For information on this question, I would recommend taking the link below, then clicking on the "age of the earth" section, then scrolling down to this question, with related articles. Even if you think you're iffy on Ross, the information here is quite interesting:

Why Did God Wait Billions of Years? www.reasons.org/resources/apologetics/index.shtml#young_earth_vs_old_earth

Scroll down to this section:

Why did God wait billions of years before creating humans?
* The Faint Sun Paradox
* Petroleum: God's Well-Timed Gift to Mankind
* Bacteria's Long Reign
* Timely Appearance of Land Life Benefits Humans
* Bacteria Help Prepare Earth For Life

[Josh]

Originally posted by HUME (even though it says Josh) 6/29/06:

"I'll grant you an overall shift from 'rudimentary' to 'complex', of course."

Thanks, that's all I intended. (We were discussing the same thing on different scales. I was referring to the "god's eye view" of history: 4 billion years ago, a couple primitive life forms; today billions of highly differentiated creatures -- vast increase in both number and complexity. By discussing extinction, catastrophe & so on, you're getting down to the details of the story of how this happened; but the fact remains that it happened.)

"I'm not necessarily sure that having a Creator God kick off naturalistic evolution answers the question any better"

Compare these 3 positions:

1. God created everything all at once (the "old school" creationist view);

2. God created some stuff, then paused for a looong time and created some more stuff, then paused, then created, etc. etc.

3. God created everything, including elaborate self-perpetuating mechanisms of adjustment and change (which we call evolution).

It's not that there's anything strange about God "taking his time" in setting everything up (a few billion years to get to humans, etc.); obviously he's not on our watch & has perfectly good reasons for whatever he does. What I'm saying is, the classic creationist model did not *predict* anything like this; that's why 19th century geology was so astonishing at the time. Evolution, on the other hand, not only predicts but requires this scenario. So, to at least some extent, the fact that earth's history unfolds (broadly speaking) in this way is supportive of evolution, and it "fits" evolution more comfortably than it fits many (any?) versions of creationism.

You're looking for disproofs of evolutionary theory, and this is one: demonstrate that the earth is only a couple million years old. And here's another: let the earth be billions of years old, but find an evolutionary anachronism like Haldane's Rabbit.

You reply that these are trivial disproofs -- "finding a rabbit in pre-cambrian strata wouldn't just challenge evolutionary theory- it would challenge all of physics. To suppose that it would take something that extreme (and only that extreme) to falsify evolutionary theory is ludicrous." Let me turn this around: the fact that the rabbit would falsify other important theories in addition to evolution simply emphasizes the strength of all these theories, and the degree to which they are interwoven with each other -- you can't simply separate them out as if they weren't connected.

In any case, I didn't intend to suggest that Haldane's Rabbit is the only conceivable disproof of evolution. I'm just trying to make a point that seems to be often missed in these discussions: a significant part of what makes evolution compelling is the accuracy of its retroactive predictions. Evolution both predicts and requires an ancient earth and a long history of life developing and altering as its environment develops and alters. It's not at all trivial that, broadly speaking, both of these predictions have been born out over a the century and a half of intense scrutiny.

[Josh]

Originally posted 6/29/06:

This threads getting a bit long, but we can pick up with Naturalistic Evolution thread I'm starting.

One last bone to pick. Good theories make accurate predictions. I think it's debatable whether evolution predicted an old earth, and the prediction that life develops and alters is debatable- is that really what the fossil record is saying?

Evolutionary theory did make false predictions, though, such as life must have arisen under stable conditions over long periods of time, and that natural selection (the only demonstrable mechanism of evolution) alone could effect the changes implied from the fossil record.

Such predictions don't damage the theory, per se, of course. It's just that a theory is in trouble when the modificiations to it are more and more outlandish, which I think we've seen- punctuated equilibrium, chaos theory, etc.. But that can be discussed on the new thread.

[Josh]

Originally posted 6/28/06:

Just one more note.

It seems to me that while I think one could argue that God actively 'guided evolution' (by inserting some changes supernaturally) from the basis of Genesis 1 and 2, as I did briefly somewhere else on this thread, that to make him only directly responsible for 'kicking the project off' doesn't do justice to all the active, creative verbage in the biblical creation accounts. I say 'do justice', because one could always say He's 'creating' through his own natural means, but I still think a strong case could be made that the wording implies ongoing intervention. This is, I think, especially brough home when the creation account ends with God resting from His creation. If the whole process could be explained naturalistically, wouldn't that process of 'creation' still be continuing to this day? But doesn't the Biblical account seem to stress strongly that mankind was the pinnacle and ending point of God's terrestrial creation?

I recognize that the Genesis account is not a science textbook, but if it is indeed inspired, then each part must have some significance. And I've always found it quite interesting that we don't have any evidence for any new speciation since modern humans appear on the scene. Granted, 50,000 (+/- 50,000) years is a pretty short window, but, still...