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Patterns of Macroevolution

Co-Post of the Month: June 2004


Subject:    Re: Macroevolution and Microevolution (closed debate)
Date:       28 June 2004

On Sun, 27 Jun 2004 22:59:30 +0000 (UTC), Aron-Ra wrote:
> "Larry Moran" wrote in message
>> "Aron-Ra" wrote:


Let's try and focus this debate on one particular issue in evolutionary theory. The debate is over the sufficiency of microevolutionary change as a complete explanation of macroevolutionary events. I maintain that microevolution alone can't account for the large scale patterns that are seen in the fossil record.


>> The known large scale changes requiring millions of years do show
>> transitions and descent with modification. This is part of the field
>> of macroevolution. It's not clear that all of the changes are
>> gradualistic (incremental changes over successive generations)
>> but that's why we have observations. If the changes aren't
>> gradualistic then we need to come up with an explanation.
>> Macroevolutionary biologists are good at that.
> Whatever you thought this debate should have been about, this is what
> I thought it was; that you would present an argument for evolution
> that is NOT a gradual or incremental sequence of species-to-species-to
> species transitions. Now you say you have some. What are they?

I'm going to use the word "gradualism" in the sense that Gould and some other paleontologists use it. I hope this isn't going to be a problem. If you dispute the terminology then please substitute some other word with the same meaning and I'll use that word.

In the most extreme case of gradualism, species represent a single population that changes gradually over time by anagenesis. In other words, the population accumulates change until it deserves to be called a new species. We can represent this extreme case as a simple linear "progression" where the original ancestral species (A) becomes a new species (G) after a period of millions of years.

   A ----> B ----> C ----> D ----> E ----> F ----> G

One could easily argue that this pattern represents nothing more than microevolution over a long period of time. Consider the population represented by species "C." Within this population, there arise various mutations that cause changes in the phenotype. Over time, these new mutations become fixed in the population by natural selection or random genetic drift. At some point in time, after several million years of gradualistic change, the population has changed so much that the new population (D) could no longer interbreed with the ancestral population (C) and a new species has been formed.

Gradualism (sensu Gould) is contrasted with the pattern of punctuated equilibrium where new species form by cladogenesis, or splitting, and not by anagenesis. Here's an example of such a pattern.

      |                           |        |-----H+
A-----|                           |------H-|
      |                                    |--------------------I+
      |        |----------------------------- B+
               |                      |---------------------D+
               |                      |
               |           |--------D-|
               |           |          |                 |---------- G
               |---------C-|          |        |------F-|
                           |          |------E-|        |
                           |                   |        |--- F+
                           |                   |
                           |                   |-------------E+

The + signs indicate species that become extinct. The main difference between this pattern and the extreme example of gradualism is that in punctuated equilibrium the predominate speciation events are by splitting of a lineage with both daughter species persisting for some length of time following cladogenesis. Consequently, at any particular point in time there are usually multiple, closely related, species in existence forming a clade.

With this sort of pattern, the end result is that an ancestral species (A) is replaced by a "modern" species (G) and this end result is not any different than the extreme gradualist transformation shown above. However, there are some important differences when it comes to explaining how these patterns are produced.

Before I describe those important differences, it's necessary to pause and discuss some things that are NOT relevant to this debate over the sufficiency of microevolution. For example, it is often noted that in addition to speciation by cladogenesis, punctuated equilibrium is characterized by rapid (in geological time) speciation events followed by stasis. According to its main advocates, the actual speciation events can be well explained by one of the main theories of speciation, namely allopatric speciation. Here's how Gould explains it ...

"The theory asserts no novel claim about modes or mechanisms of speciation; punctuated equilibrium merely takes a standard microevolutionary model and elucidates its expected expression when properly scaled into geological time."


In other words, changes within a population play an important role in the evolution of the new population following its separation from the parent population. [I would argue that a complete explanation of allopatric speciation requires taking into account the geographical factors and, in that sense, it's more than just population genetics. But we'll leave that debate until later.]

As described above, the extreme gradualist pattern is easily explained by anagenic speciation, which is perfectly consistent with what we know about microevolution and changes within a population. The punctuated equilibrium pattern, on the other hand, has to account for the differential survival of co-existing species within a clade. Why do some species survive while others become extinct? Why is this important?

"... punctuated equilibrium makes its major contribution to evolutionary theory, not by revising microevolutionary mechanics, but by individuating species (and thereby establishing the basis for an independent theoretical domain of macroevolution)."

Gould, S. J. (2002) p. 781-782.

What is he saying? He's saying that the observed pattern of punctuated equilibrium, which may or may not be the predominate macroevolutionary pattern, establishes a higher level of evolution. In this higher level, the species become the "individuals" within a "population" formed by the clade. The differential birth and survival of species within the clade occurs by species sorting or species selection and this level of evolution is distinct from changes in the frequency of alleles within a population.

In the case of species sorting, microevolution is uncoupled from macroevolution because a proper explanation of evolution requires this description of the birth and death of stable species. This is true even though there may not be profound new mechanisms of evolution that can't be explained by competition between organisms within populations. "In this version, we need a descriptive, but not a causal, account of macroevolution based on species as individuals." (Gould, p. 784)

In the case of species selection, the differential survival of species within a clade arises from properties of the species as a whole. These properties cannot be reduced to the level of organisms within a population. Gould presents the case for true species selection and argues that "validation of this argument would establish a genuinely causal and irreducible theory of macroevolution." (Gould, p. 784)

Aron, I've tried to simplify this in order to present the basics so we can discuss whether microevolution is sufficient to explain all of macroevolution. There are many complications. For example, gradualists (sensu Gould) do not deny speciation by branching. They simply deny that splitting will lead to species sorting or species selection or that it produces the punctuated equilibrium pattern of macroevolutionary change. Similarly, supporters of punctuated equilibrium have much more to say about the importance of higher level processes.


>> > But "large-scale" changes? What is "large-scale"? It certainly
>> > isn't the "big BIG" changes so many anti-evolutionists claim it
>> > is; the vast macroevolutionary leaps they complain about, based on
>> > their refusal to accept transitional species.
>> Right. We're not talking about anti-evolutionist theories.
> I think you are if you say you can come up some example of evolution
> that did not involve an incremental series of subtle changes over a
> gradual species to species to species transition, such as I say all
> biological evolution requires.

Do you understand now why punctuated equilibrium isn't an anti- evolutionist theory? Do you understand why species sorting and species selection might require explanations that go beyond the gradual species to species transition that could be explained entirely by microevolution? Do you understand the concept of hierarchical theory of evolution? (I'm not asking that you agree with species sorting, we can debate that later.)

>> > Are large-scale changes not also the result of relatively-slight,
>> > incremental stages?
>> Possibly not. Probably, not exclusively.
> Well, that's my position. To counter it, you'll need to provide the
> exceptions that make it not-exclusive.

The large scale changes seen in the macroevolutionary pattern of punctuated equilibrium indicate that between species sorting/selection is an important part of evolution. This means that relatively slight incremental changes are not the only thing happening in evolution at this scale.


>> [The idea that all large scale changes are due exclusively to
>> cumulative small changes is what's being debated.]
> Right, and you're trying to argue that there are large changes that
> are not a matter of cumulative small changes; something to defend
> the genetic "gap", which I said didn't exist. Snip all the rest
> of this nonsense, if you like, and just show me that there is
> something completely different going on above the species level
> that is not also a factor below it.

I've tried to show you one thing that's going on above the species level that is different from changes in the frequencies of alleles within a population. That "something" is the differential birth and death of species within a clade and the long-term trend that it produces. How did I do?

Larry Moran

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Conversation with a Muslim

Co-Post of the Month: June 2004


Subject:    OT: Islam and America
Date:       2 July 2004

I mentioned a few months ago that I had the opportunity to sit next to a young Pakistani cardiologist on a flight to Austin. I'd like to talk about that some more...let's call the Pakistani doctor, Ben.

Ben is a middle child in a large Pakistani family of moderate means. His home had no electricity or running water, yet he was considered middle class in his culture simply for having a home at all. His family did laundry for a hotel and sold carpeting/sheeting on the side. He worked as a hotel maid to earn money for night classes, in addition to his high school classes, to prep for college. During this time, he took classes in mathematics, physics, chemistry, and BTW, English, French, and German (he's currently taking night classes for Chinese). By the time Ben graduated High School, he could do multiple integrals in polar co-ordinates and write his answer in three languages. In college, he worked a full time phone center job while earning a 3.8 GPA in pre-med. NYU I think it was, but not sure. He also got married and started a family, one child after another virtually every year, for five years. During this time, he went on to Stanford, earned his MD, did his residency in an LA emergency room while raising those five kids. He specialized in cardiology, took some additional classes and internships for that specialty, and now has a partnership in a thriving cardiology practice in Orlando, Florida. Incidentally, Ben is 29 years old!

I asked him how he pulled all that off coming from such a disadvantageous position. He replied somewhat haltingly that he was very.. religious... "I don't know...I'm a religious fellow" he said guardedly, as if worried I'd think he was a nut, "and I think that helped. I owe Allah a great debt for my health and my children and my own life. I know that sounds crazy to you being an American, but that's how I see it..."

I did mention that he didn't sound crazy at all. In fact, he's the most polite, intelligent, thoughtful, and rational person I've ever struck up an impromptu flight conversation with. And I told him so. He was so polite he soon began asking me what my interests were, feeling he had been doing all the talking. Well, I was afraid to bring it up, but I wanted to be honest. So I told him one of my hobbies was fighting pseudo-science and advocating real science; like creationism vs. evolution. His response caught me off guard. It was something like "I understand. The US leads science, but I meet people who really think the Earth is 6000 years old, or that evolution never happened. Why is that?"

I couldn't believe it. I asked him how his religion (Islam) meshes with evolution. He explained that basically there is no problem, as evolution could have been the method employed, and added that only a fool would deny evolution given the evidence. Although he didn't state it exactly like this, his view seemed to be that truth (evolution) cannot contradict truth (Islam). So there is no conflict with evolution and Islam. Simple as that.

So here is a deeply religious Muslim, worked his tail off in the name of Allah, gives like 10% of his income to his temple, he won't even own bonds or interest-bearing instruments for crying out loud because interest income violates some kind of Islamic principle (he can own dividend paying stocks or private ventures which pay out earnings, but no preferreds or yield vehicles). And he accepts evolution BECAUSE of the evidence.

And what's more is I think there are plenty of Bens out there in the Islamic world. Just as we have rational Christians on this board, and a few nutters, there are guys like Ben, ...and well...Jam on AOL for the token Muslim nutter. What's so very sad is that we as a country are not doing well with these rational Muslims. We're in fact p***ng them off and driving them away.

What does creationism represent? Ignorance. Dogma over analysis, fiction over fact. Credulity. I would even say it represents stupidity in some cases. It's certainly at times silly or funny, and at other times tragic, as we witness an eternal parade of creationist victims spouting the same endlessly recycled crap on this forum day after day. Murphy AKA Sockpuppet, Ed C, Pagano, these are trolls who are not only ignorant, they're proud of their ignorance and wear it like a badge. Creationism in the face of evidence represents some of the greatest flaws in humanity's psyche. It's our propensity to believe gone awry. It's symptomatic of the same kind of mindset found in Holocaust deniers, or Scientologists. It's disturbingly similar to the kind of thinking that leads to a Jonestown, or a Heaven's Gate.

Now, the reason I think we need to forge a healthy relationship between the West and the moderate Muslim world, the Bens of the planet, is not because I think they're swell guys who would be a blast at a bachelor party. It's because the alternative could spell the end of our culture. These guys are smart. They have nukes. They have WMDs for real. And you don't want an Islamic fanatic (or an Evangelical fanatic, or any fanatic for that matter), who ardently believes in an Islamic version of the Rapture, with his finger on the nuclear button. You want Ben in charge of stuff like that. Hell, you'd rather have Saddam Hussein or Stalin in charge of stuff like that because, despite being ruthless, cunning killers, they happen to WANT to stay alive and in power. The fanatic views the Earth as a sort of a temporary camping trip before going back home to the luxury of Heaven.

Ben told me something else; he said that in Pakistan, Osama bin Laden is perceived like a living Luke Skywalker, mysticism and all. And you can guess who plays the Evil Empire. Meanwhile, back in the real world, Osama is consolidating his power in Pakistan, the home of some of the brightest nuclear scientists in the world, and Saudi Arabia, the world's energy source. And what are we doing about it? We're....occupying Iraq...p***ing off more Muslims, losing men and women, committing heinous acts against Iraqis randomly collected, and bleeding money like a stuck pig. A buddy of mine just got his tour extended for the THIRD time. Right now the Evil Empire is busy ticking Muslims off and proving their darkest fears about our morals and methods.

Anyway, in the mind of a rational Muslim, I gather Osama is kinda like O. J. Simpson was/is to a black ghetto dwelling LA resident who has been hassled by the cops all of his life. The blacks know OJ did it and that what he did was terribly wrong, they just hate the system that has crushed them for so long that they're happy to see OJ 'get one over on The Man'. When black people were jumping up and down after OJ was acquitted shouting 'we won, we won' they didn't give a rat's *** about OJ. They meant THEY as black people finally got the same privileges for a wealthy black guy that wealthy white guys have been getting for centuries. Namely, getting away with murder.

Al Qaeda is kinda like that in some Muslim minds apparently. The rational Muslim knows that 9-11 was wrong, it violated about every principle of Islamic theology imaginable, and they would turn people in if they suspected they were planning an attack, even fellow Muslims. But it did get one over on 'The Man'.

We need to configure a policy for dealing with Ben that WORKS, because his brethren are incredibly smart, highly motivated, and there are a LOT of them. Right now our policy is built on prejudice and oil, and it isn't working. They can contribute a great deal to our science and technology. They WANT to like America. But for some odd reason, when dealing with the Middle east, the US suddenly acts like an imbecile bullying *******.

Example: The biggest obstacle to a large Islamic state spanning from the Mediterranean to the Pacific Ocean is Iran. Iran does not hang well with Sunni fundies. They're becoming more progressive and moving away from fundamentalism. They had a legit revolution, brought America to its knees, without killing a single American. Iran has nukes, and they are willing to fight hard. Iran has a credible government which couldn't get sucker punched by any of Osama's "they're western puppets" stuff that plays so well, and so true, for some Arab states. Iranians are highly educated, and, I think, delightful people. They're deserving of our respect and they would make a formidable ally, or a terrifying enemy. They're smack dab in the middle of the theocratic empire Osama wants to carve out.

So wouldn't you think we'd snuggle up to Iran, admit how bad we screwed them, and be pals? Well no, of course not. Iran is part of the "Axis of Evil". As much as it pains me to note, a lifelong Republican, we have to eject Bush and let Herman Munster take a shot at the helm. See, I'd rather have Ben on my side than against me. And if Ben and I, a devout Muslim and an American atheist, can agree on evolution, we can agree on coexistence as well. For both are rational. Vote wisely, my friends.


[Return to the 2004 Posts of the Month]

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