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Author Topic:   All species are transitional
Parasomnium
Member (Idle past 859 days)
Posts: 2191
Joined: 07-15-2003


Message 1 of 246 (248813)
10-04-2005 9:48 AM


Creationists often hail the lack of transitional fossils as damning evidence, if not the death blow for the theory of evolution. Such arguments are often countered by pointing out that the fossil record is bound to be incomplete, is not the only evidence, is in fact a minor part of the evidence, etc, etc. Also, evolutionists explain, absence of evidence is not evidence of absence.

But I think a very important point is often overlooked when considering the argument of transitionals, when in fact it could be a very powerful weapon in the debate, if it is properly understood. What I am talking about is that the concept of 'transitionals' is a bit misleading. It is misleading in that it forces upon us - but mostly upon the undiscerning creationist mind - the distinction between "finished" and "unfinished" creatures.

Thus the finished creatures belong to a species, while the unfinished creatures are deemed somewhere "in between" species. Also, a transitional creature is supposed to exhibit useless features, or even defective features, because they are not the "finished product". But this is a false picture. The reality is that all species are transitional. There is no such thing as a "finished species". It's a mirage, for two reasons.

First, the term 'species' is an arbitrary, man-made concept. The system of classification in biology, of which 'species' is a layer, has been revised more than once, to accomodate new insights in the relatedness of newly found creatures to ones already known. Also, there are several definitions of the term 'species'. One definition takes interbreeding as its criterion. Ernst Mayr defines 'species' as:

quote:
"groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups"

But interbreeding assumes sexual reproduction. So what about all those creatures that reproduce asexually? How are they classified into species? Enter the concept of a "morphological species", that is to say, when two creatures are similar enough, we call them a species, and when they differ too much, they are "clearly" two species. But what is "similar enough"? When do they "differ too much"? All in all, it seems obvious that the concept of 'species' is a bit problematic.

Second, the term 'finished' presupposes a plan. Something can only be called 'finished' if it is known in advance what the thing is going to look like. But evolution advances by random mutation and natural selection, making it logically impossible for there to be a plan. And if there is no plan, then a species cannot rightly be called 'finished' or 'unfinished'. It simply is what it is: a species in its own right.

To illustrate the point that all species are transitional, here's a thought experiment. Let's create a row of numbers, by following a simple rule: we start with the number 1 and create each following number by adding 1 to the preceding number. Let's repeat this until we have reached 1 million.

Now we have a long row of numbers, with small numbers at one end, and large numbers at the other. Everyone will probably agree that 1 is a small number, and a million is a large number. The number 2 is also a small number, as are 3, 4 and 5. At the other end there are more large numbers: 999,999 is large, so are 999,998 and 999,997. However, the row is continuous, so the question is: where in the process that created the row did a small number give rise to a large number? Whatever boundary is taken as the point of transition, the numbers on both sides of the divide differ by only one, so it is a bit difficult to maintain that the one is a small number and the other is a large number. A solution could be to introduce 'intermediate' numbers, which are neither small nor large, but, obviously, intermediate.

But is that really a solution? Actually, no. Because now we have not one, but two boundaries to determine. When is a number still small, and when is it intermediate? What intermediate number gave rise to a large number? We find we still have the same problem, only twice. And introducing still finer gradations just adds to our problems, until...

Until we come to the point where each number is in its own division, and the dilemmas disappear all of a sudden. But now our divisions no longer provide us with more information about the numbers than the numbers themselves do, effectively making the divisions obsolete. This means that there are no discrete dividing lines to be drawn. The transition takes place along the entire range of numbers. Each number is itself a transitional, from small to large.

What we need to realise is that we are trying to impose an arbitrary system of discrete divisions on a continuous set of elements. With species it is no different. If you translate the example of the numbers to species, you can imagine a continuous sequence of intermediates from any ancestor you'd care to start with, right up to yourself. You are the same species as your parents, and they the same as theirs. At the other end of the line, the ancestor you started with is the same species as its offspring, and they are the same species as their offspring.

But if you went back far enough in the lineage so that the ancestor you start with is a tree-dwelling primate, then obviously this ancestor is not the same species as you. There must be transitionals. But wherever you look in the lineage, locally you cannot pinpoint any real transitions. That's because the transition takes place all over the lineage. Each and every one of your ancestors is a transitional. And if you have children or plan on having them, you are a transitional yourself.

The next time a creationist asks "Where are the transitionals?", you can answer "Look around you."

{edited for spelling}

This message has been edited by Parasomnium, 30-Dec-2005 02:08 PM


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AdminPhat
Administrator
Posts: 1911
From: Denver,Colorado USA
Joined: 12-03-2004


Message 2 of 246 (248842)
10-04-2005 12:16 PM


Thread moved here from the Proposed New Topics forum.
    
robinrohan
Inactive Member


Message 3 of 246 (248848)
10-04-2005 12:56 PM
Reply to: Message 1 by Parasomnium
10-04-2005 9:48 AM


Great stuff, Parasomnium.
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JustinC
Member (Idle past 3006 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 4 of 246 (248850)
10-04-2005 1:17 PM


This is kindof a trivial point, but it a creature dies without breeding then it isn't transitional.

Or, if we are using "species" as a valid classification then a species that goes extinct, without some of it's populations evolving into another species, is not transitional.


Replies to this message:
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Chiroptera
Member
Posts: 6616
From: Oklahoma
Joined: 09-28-2003
Member Rating: 4.8


Message 5 of 246 (248853)
10-04-2005 1:24 PM
Reply to: Message 4 by JustinC
10-04-2005 1:17 PM


Maybe. But if the platypus went extinct, wouldn't it still be considered a transitional between placental mammals and non-mammal therapsids? Transitional isn't a direct link between a ancestor and descendent species -- a transitional is a species that retains many primitive features of the common ancestor as well as derived features that are found in related lineages that have lost the primitive features.

Edited to add the last six words.

This message has been edited by Chiroptera, 04-Oct-2005 05:39 PM


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Parasomnium
Member (Idle past 859 days)
Posts: 2191
Joined: 07-15-2003


Message 6 of 246 (248902)
10-04-2005 4:46 PM
Reply to: Message 4 by JustinC
10-04-2005 1:17 PM


Creatures, or species?
JustinC writes:

if a creature dies without breeding then it isn't transitional

That's why I specifically mentioned ancestors, and not just any odd creature:

quote:
[...] imagine a continuous sequence of intermediates from any ancestor you'd care to start with, right up to yourself. [...] Each and every one of your ancestors is a transitional. And if you have children or plan on having them, you are a transitional yourself. {emphasis added, P.}

If a creature dies without breeding, it can't possibly be one of your ancestors.

JustinC writes:

Or, if we are using "species" as a valid classification then a species that goes extinct, without some of it's populations evolving into another species, is not transitional.

Now you have point. A trivial point, by your own admission, but a point nevertheless. Thanks for sharing it, I hadn't thought of it.


We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Brad McFall
Member (Idle past 3195 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 7 of 246 (248943)
10-04-2005 7:20 PM
Reply to: Message 4 by JustinC
10-04-2005 1:17 PM


nice!
In fact I DO NOT CONSIDER this a "trivial point". There is so much biology lost by not being able to relate deaths to genetic biophysics conceptually. Creationists have very much to contribute by having thought about death a lot more than evolutionists. A dying gene combination might influence a living phenotype by the average deaths in the dying genome of a larger clade in the phenotype providided under the same dominance/recessive traitsystem) if the symmetry works out account allele wise. This is the essence of various ways to imagine that biology trumps any meme both behaviorally and ecologically no matter the genes heirarchically.

It is not trivial by my thinking.I have not reified the thought to the Cambrian level but it might be possible.

This message has been edited by Brad McFall, 10-04-2005 07:21 PM


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JustinC
Member (Idle past 3006 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 8 of 246 (248944)
10-04-2005 7:21 PM
Reply to: Message 5 by Chiroptera
10-04-2005 1:24 PM


I don't know if I agree. Where did you get your definition of transitional species? I always considered a transitional to be a direct link between two species. So it would have to fit in the timeline between the two species and share features of the oldest species while showing characteristics of the later one.

I wouldn't say the platypus is transitional, I would say it is closely related (atleast morphologically) to the the transitional species between placental mammals and non-mammal therapsids.


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NosyNed
Member
Posts: 8842
From: Canada
Joined: 04-04-2003


Message 9 of 246 (248948)
10-04-2005 7:24 PM
Reply to: Message 6 by Parasomnium
10-04-2005 4:46 PM


not transitional without descendents?
if a creature dies without breeding then it isn't transitional

That's why I specifically mentioned ancestors, and not just any odd creature:

This, like so much else, depends on the definition. If a transitional is one which "posseses features of two currently distinct higher taxa". The an animal doesn't have to have descendant species to be this kind of transitional.

At some point in time there were probably 100's or 1,000's of species that were all cousins and all part way along the path from dinosaur to bird. It may be that exactly one of these species gave raise to all modern birds or certainly only a handful of them. But I'd claim that ALL of them were transitional -- that is straddling the gap between the two higher taxa.


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robinrohan
Inactive Member


Message 10 of 246 (248963)
10-04-2005 8:00 PM
Reply to: Message 7 by Brad McFall
10-04-2005 7:20 PM


Odd (and clear) comment from Brad McFall
Creationists have very much to contribute by having thought about death a lot more than evolutionists.

What an odd comment.


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Brad McFall
Member (Idle past 3195 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 11 of 246 (248983)
10-04-2005 9:42 PM
Reply to: Message 10 by robinrohan
10-04-2005 8:00 PM


Re: Odd (and clear) comment from Brad McFall
It is too hard and long to render it without that oddity. It might be that baramins are wrong and hierarchicalization will not be pursued by creationist in a 100yrs just as radioactive dating changed the way creationists worked on rock time but currently I dont see much evo space contrarily or not for species like dying individuals or populations DEFINED by the population GENETICALLY as would be required to work that out ecologically. The issue of death would conceptuall bear on if the double phenotypic construct I implicated be retained or if some other restruction of the division of geneotype and phenotype be proposed either by advances in baramin logic where evos rear the fear to tred the trodding or even heaven forbit (gosh did I say that) Wolfram Science prevails where i think not even the current foregaurd of evolutionary thought will survive. We do not even have the shampoo to wash this greasy fleshy stuffed out so how could I know. I do know however that the thought evolutionarily of death influencing life is clearer than mixed mud. Mayr simply tried to define that out of biology. I think others perhaps should have tried to define Wright's gene combination in group theoretical terms quantum mechanically. Maybe Ned would tell me this is impossible but I doubt not.
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Mammuthus
Member (Idle past 4638 days)
Posts: 3085
From: Munich, Germany
Joined: 08-09-2002


Message 12 of 246 (249012)
10-05-2005 5:39 AM
Reply to: Message 1 by Parasomnium
10-04-2005 9:48 AM


Excellent post! You might want to retitle it to all individuals (who reproduce) are transitionals.

quote:
What we need to realise is that we are trying to impose an arbitrary system of discrete divisions on a continuous set of elements. With species it is no different. If you translate the example of the numbers to species, you can imagine a continuous sequence of intermediates from any ancestor you'd care to start with, right up to yourself. You are the same species as your parents, and they the same as theirs. At the other end of the line, the ancestor you started with is the same species as its offspring, and they are the same species as their offspring.

The discrete unit is the individual and in fact there is a bit more difference than one would assume. You are a jumble of the genes of your parents. But in addition, each indivdual carries mutations not present in either parent and thus, the genome contains novel variation both in content and in recombined inherited variation. This also overcomes some of the problems with dealing with asexual organisms as they also accumulate mutations though many individuals may be clonal. I think the problem is people confuse the discrete character which is the individual with the non-discrete character which is the population or species. If you add the number of unique individuals composing the effective population size, you have a huge genetic and morphologic pool of variation for most species. Even a single population has a huge amount of variation. Which one individual represents the species? Which variant is non-representative? Which individual represents a transition from one state to another? If speciation is occuring, how would you know? It is often defined as reproductive isolation i.e. accumulation of mutations to the point that members of a previously single population cannot interbreed. But ring species demonstrate that this need not be a discrete characteristic and there are "species" that can potentially interbreed but in the wild do not..or thier offspring quickly disappear from the gene pool i.e. forest African and savannah African elephant hybrids. As you point out, when you are comparing a parent to the offspring, you would not notice that it is a "transitional" as it may represent only a relatively small incremental difference morphologically and genetically. But if you compare an individual to some other species, or even a population that is now extinct (i.e. neandertal genes for example) you suddenly see a much greater difference...this progresses the farther you go back in generations. So the difference between me and my father will be smaller than that between me and my grandfather which will be much smaller than that between me and any H. erectus individual and so on. It is sort of like growing taller...each day you may look in the mirror and not seem to be any different. But if you look at yourself when you were 5 and then 10 you would see a huge difference.


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Parasomnium
Member (Idle past 859 days)
Posts: 2191
Joined: 07-15-2003


Message 13 of 246 (249014)
10-05-2005 5:56 AM
Reply to: Message 7 by Brad McFall
10-04-2005 7:20 PM


Brad, Evolution & Death
Brad McFall writes:

There is so much biology lost by not being able to relate deaths to genetic biophysics conceptually.

Well, normally we say that evolution is directed by natural selection. But we could easily rephrase that as "evolution is directed by non-random death." They are two sides of the same coin. To assess your wealth, you can either consider what you've got left, or you can count your losses. The nett result is the same.

But that may not be what you mean. The problem is that I don't understand what you mean. Could you explain?* Please concentrate on this phrase from your other post: "species like dying individuals".

* Preferably in green-grocer speak.


We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium
Member (Idle past 859 days)
Posts: 2191
Joined: 07-15-2003


Message 14 of 246 (249015)
10-05-2005 5:58 AM
Reply to: Message 9 by NosyNed
10-04-2005 7:24 PM


Re: not transitional without descendents?
NosyNed writes:

This, like so much else, depends on the definition.

[...]

At some point in time there were probably 100's or 1,000's of species that were all cousins and all part way along the path from dinosaur to bird. It may be that exactly one of these species gave raise to all modern birds or certainly only a handful of them. But I'd claim that ALL of them were transitional -- that is straddling the gap between the two higher taxa.

It's all a matter of where we draw the boundary between taxa, like I illustrated in my opening post. Popularly, you could say that "the birds descended from the dinosaurs". You'd be right, in a very loose sense of the word 'descended'.

But if you zoom in, so to speak, you find that some, if not most subtaxa of "dinosaurs" did not give rise to the taxon "birds" at all. Some dinosaurs may have been birdlike and gone extinct without leaving a continuous lineage resulting in birds. They cannot have been the ancestors of modern birds, but you could call them transitional because they are part of the blurry taxon "birdlike dinosaurs", which we could imagine between dinosaurs and birds.

So, zooming out again - but not all the way - we get: "the birds descended from birdlike dinosaurs which in turn descended from dinosaurs". In that sense, "birdlike dinosaurs" are the ancestors of birds, even if some of the birdlike dinosaur species went extinct.

JustinC writes:

I always considered a transitional to be a direct link between two species. So it would have to fit in the timeline between the two species and share features of the oldest species while showing characteristics of the later one.

That's also how I would define a transitional, at least for the sake of the purpose of this topic, which is specifically targeted at the creationist argument of the "missing" transitionals. I'm sure a more elaborate discussion can unfold if we allow a more relaxed definition of transitionals, but I would like to engage a particular creationist misconception first.

This message has been edited by Parasomnium, 05-Oct-2005 12:13 PM


We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Brad McFall
Member (Idle past 3195 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 15 of 246 (249025)
10-05-2005 7:17 AM
Reply to: Message 13 by Parasomnium
10-05-2005 5:56 AM


Re: Brad, Evolution & Death
To be useable the death part would need a definition that refers to a population. This would not be a class necessarily. It would enable one to speak about the species as an individual much as Newton spoke of fermentation and death in creatures being like a dying "central" Earth or earths.

Now one can conceive of species as entities (statistical in the best Mendelian sense if one wished) without borders and yet a major part of a hierarchical process or one without that unknown and possible unknowable borders. I think taxonomy needs to be flexible but it is probably one of the least flexible disciplines within biology. Julian Humphries simply failed to notice that any statistic could be invalidated by a proper normalization. There is resistance to viewing these things as definable. If there is any sense to the Baramin notion then the baramin divisions are so cognized. Creating a possibly different notion in the same thought requires committment to particular connectivities of levels of organization IRRESPECTIVE to levels of selection and think it is for that reason and not the c/e issue that causes intransigence.

I was thinking more of my comments on Carnap. Use the EVC Search function if you like or try
http://www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=6&t=441&m=51#51

I know I have not exhausted that analysis but presently I am working on comparing Kant's four figure subtility to DKNF TO any normalization via non economically constrained views of potential biological research. It depends on there being (some failure to observe) a simple juxtaposition of four creatures which does not mean any rate of change is thinkable IF normalized by some kind of population (supramolecular and dead) but this is also meaning to mean that organacism is dead memetically. I know this is not the common view. I do know that there is no way that Cornell Vision is identical to A D Whites' as the president last week said here in no uncertain tones that it was. It is not. Simple as that no matter the Godlessness.

It would be questionable to me to simply say evolution is DIRECTED non-random death whether by a designer, an alien or jiggling molecules. You would be tokenizing the relation of genetic isolation by distance and any geographic measure of species diversity and that is only doable should both Darwin and Mendel be seamlessly related in the details. Inventories rather than wealth or income is a better analogy. Deathful demes are unusable inventories, they might be genetical reverse artifically selected. Ecosystem engineering might "train" migrating demes to alter the token distance that the earth rotates or was called endemic. The issue is how is the accounting done. I use water balance. Thus it is important to look for water on Mars but it might be expermented on on the Moon instead while not politically possible still on Earth. I think one can analyze the two sides of ledger back to Mendel further than Carnap. That is all. I hope that clears up the question of my mortality.

Mammy said

quote:
But in addition, each indivdual carries mutations not present in either parent and thus, the genome contains novel variation both in content and in recombined inherited variation.

I only tried to scale this attribute IN creatures onto the largest scales thought about. I could be wrong where Mammy is correct.

This message has been edited by Brad McFall, 10-05-2005 07:38 AM


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