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Author Topic:   Tautology and Natural Selection
JustinC
Member (Idle past 4843 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 1 of 130 (46626)
07-21-2003 1:37 AM


Natural Selection
1. Organisms produce more offspring than can survive
2. Organisms vary from one another in heritable ways
3. Some of heritable variations will affect and organisms ability to reproduce in a given environment
4. Variations which increase an organisms ability to reproduce viable offspring in a given environment will be passed on through the next generation
So basically this states that there is non-random survival in nature (not-including genetic drift).
So if you deny this then you feel all organisms survive randomly, and that properties such as speed, coordination, and intelligence have nothing to do with reproductive success.
The trouble comes in the Spencer's phrase "survival of the fittest".
Some have said to drop the phrase altogether; that its tautologous, and not an accurate description of natural selection. I would like to, but it does seem (to me....I could be wrong)to describe natural selection accurately. Here's my interpretation (influenced by many authors)of it:
No organism survives indefinately, so what survives? Lineages survive, more specifically lineages distinguished by a certain trait (compared to the ancestor lineage). So how can we define fitness? It would be nonsensical to say that fitness is defined by what increases a certain lineages survival, because the lineage would be different once a new heritable trait (that affects reproduction) emerges in it. So can fitness be defined as an organisms ability to leave a certain amount of viable offspring in a given environment?
So the phrase now would be interpreted as "survival of the lineage with a certain trait that allows its members to leave the most offspring in a given environment"
Is this all viable analysis?
I've always had a bit of trouble resolving the tautological issue, so I'd like some input if anyone wouldn't mind.
JustinC
Also, for the record I'm an Evolutionary Biology Major (sophomore).

Replies to this message:
 Message 2 by crashfrog, posted 07-21-2003 2:01 AM JustinC has replied
 Message 3 by Syamsu, posted 07-21-2003 5:26 AM JustinC has not replied
 Message 5 by MrHambre, posted 07-21-2003 10:25 AM JustinC has replied
 Message 26 by Peter, posted 07-22-2003 11:14 AM JustinC has replied

  
crashfrog
Member (Idle past 1466 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 2 of 130 (46628)
07-21-2003 2:01 AM
Reply to: Message 1 by JustinC
07-21-2003 1:37 AM


So can fitness be defined as an organisms ability to leave a certain amount of viable offspring in a given environment?
I believe that is exactly how it is currently defined. Fitness is a measure of the reproductive success of an individual.

This message is a reply to:
 Message 1 by JustinC, posted 07-21-2003 1:37 AM JustinC has replied

Replies to this message:
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Syamsu 
Suspended Member (Idle past 5589 days)
Posts: 1914
From: amsterdam
Joined: 05-19-2002


Message 3 of 130 (46639)
07-21-2003 5:26 AM
Reply to: Message 1 by JustinC
07-21-2003 1:37 AM


The problem here is that you are confusing preservation with producing more offspring then the other. You have to pick one or the other as the point of the theory. Preservation occurs when organisms reproduce faster then they die, more or less. Producing more then the other, well that's just a comparison, and doesn't have preservation as a logical consequence but relative populationshare. I think with survival of the fittest you are basically suggesting that variants are negative selective factors to each other, that they encroach on and replace one another, Malthusian Darwinism. Fitness is commonly understood in terms of preservation, reproducing faster then dying, but the meaning in standard Natural Selection is a relative propensity for a populationshare. Fitness and heritability of traits that are uniform in a population is then zero, in standard Natural Selection, because there is no variant to compare to when a trait is uniform in the population.
regards,
Mohammad Nor Syamsu

This message is a reply to:
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Replies to this message:
 Message 4 by Admin, posted 07-21-2003 9:08 AM Syamsu has replied

  
Admin
Director
Posts: 12995
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.3


Message 4 of 130 (46654)
07-21-2003 9:08 AM
Reply to: Message 3 by Syamsu
07-21-2003 5:26 AM


Hi Syamsu!
You may discuss your particular understanding of fitness, variation and natural selection anywhere in the Free For All forum, or you may introduce a single thread to discuss it in the Evolution forum, but you may not raise it in other threads.
I should perhaps explain this restriction for the benefit of members who may be new or were not active some months ago when Syamsu moved his discussions to the Free For All forum. It sometimes happens, and Syamsu is a case in point, that someone with a unique perspective or interpretation joins EvC Forum. He begins posting messages in various threads that reflect this unique perspective, and pretty soon these threads all bog down in discussion of this single issue. This is viewed as undesireable, and so when it happens then discussion of the unique viewpoint will be restricted by board administration to a single thread.
It was Peter Borger's refusal to restrict discussion of GUToB to a single thread that resulted in his suspension of posting privileges. Naturally, they will be restored as soon as he lets board administration know via email that he's willing to abide by this restriction.
------------------
--Percy
   EvC Forum Administrator

This message is a reply to:
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Replies to this message:
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MrHambre
Member (Idle past 1392 days)
Posts: 1495
From: Framingham, MA, USA
Joined: 06-23-2003


Message 5 of 130 (46662)
07-21-2003 10:25 AM
Reply to: Message 1 by JustinC
07-21-2003 1:37 AM


Natural selection is not a tautology, but it can be described in a way that makes it sound like circular reasoning. Yes, if 'fitness' refers to the ability to reproduce most effectively, then the fittest organisms in a population will indeed leave the most offspring. That's not saying anything about fitness.
The problem lies in the fact that we can only accurately determine in retrospect what trait(s) conferred fitness upon certain individuals in a population, since we need information about every aspect of the fitness landscape: competition among variants, availability of resources, predation, parasitism, and countless other factors of greater or lesser importance. Not only that, but we need to know many things about the population itself such as diet, mating and migration patterns, etc., and the importance of any of these factors may also only be obvious in retrospect.
People's view of natural selection as 'survival of the fittest' makes it easier for the incredulous to mock it as a just-so story. The better way to see it is 'elimination of the un-fittest.' This is the horrible truth of nature, and the reason we resist any attempt to ascribe a grand Design to its process: the vast majority of any population is doomed to early death without issue, and the vast majority of all species will eventually go extinct.
Hence, our focus on the survivors is like trying to gauge the probability of winning the lottery by looking at a long list of lottery winners. Populations change because certain alleles are selected for out of a wide range of candidates. The machine of natural selection eliminates every combination except a few. Since the machine has so much raw material in terms of variation, we should indeed expect to see such novelty and complexity emerge from the algorithm. But let's remember that this process is also a hideously wasteful machine whose operation also requires an abominable amount of loss.
{edited to correct typo}
------------------
Quien busca, halla
[This message has been edited by MrHambre, 07-21-2003]

This message is a reply to:
 Message 1 by JustinC, posted 07-21-2003 1:37 AM JustinC has replied

Replies to this message:
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Syamsu 
Suspended Member (Idle past 5589 days)
Posts: 1914
From: amsterdam
Joined: 05-19-2002


Message 6 of 130 (46671)
07-21-2003 11:06 AM
Reply to: Message 4 by Admin
07-21-2003 9:08 AM


I'm sorry but there is no unique viewpoint in my post as far as I'm aware.
regards,
Mohammad Nor Syamsu

This message is a reply to:
 Message 4 by Admin, posted 07-21-2003 9:08 AM Admin has replied

Replies to this message:
 Message 7 by MrHambre, posted 07-21-2003 11:14 AM Syamsu has not replied
 Message 8 by Admin, posted 07-21-2003 1:39 PM Syamsu has replied
 Message 19 by nator, posted 07-21-2003 10:09 PM Syamsu has not replied

  
MrHambre
Member (Idle past 1392 days)
Posts: 1495
From: Framingham, MA, USA
Joined: 06-23-2003


Message 7 of 130 (46673)
07-21-2003 11:14 AM
Reply to: Message 6 by Syamsu
07-21-2003 11:06 AM


No kidding
You beat me to that one, Sy!
------------------
Quien busca, halla

This message is a reply to:
 Message 6 by Syamsu, posted 07-21-2003 11:06 AM Syamsu has not replied

  
Admin
Director
Posts: 12995
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.3


Message 8 of 130 (46712)
07-21-2003 1:39 PM
Reply to: Message 6 by Syamsu
07-21-2003 11:06 AM


Syamsu writes:
I'm sorry but there is no unique viewpoint in my post as far as I'm aware.
Okay, then become aware:
Syamsu in message 3 writes:
Fitness and heritability of traits that are uniform in a population is then zero...
Because over the past year this issue has proven to be one upon which no progress in discussion can be made with you, not even this camel's nose of your unique viewpoint on variation and NS is permitted for you. Nor your unique perspectives on social Darwinism. You may have one thread each to discuss these issues, and they're not to be raised elsewhere. Or you can return to the unmoderated Free For All forum.
This should in no way be construed as limiting any other member, though naturally the guideline about staying on topic should always be considered.
------------------
--Percy
   EvC Forum Administrator

This message is a reply to:
 Message 6 by Syamsu, posted 07-21-2003 11:06 AM Syamsu has replied

Replies to this message:
 Message 10 by Syamsu, posted 07-21-2003 2:27 PM Admin has replied

  
NeilUnreal
Inactive Member


Message 9 of 130 (46713)
07-21-2003 2:09 PM


There's nothing false about a tautology, it just doesn't entail any implications that aren't in the original statement. (e.g. (A or ~A) implies {} ) If we knew everything about the empirical world, our body of knowledge would be tautologus by definition. If the original statement is not founded on correct knowledge about the empirical world, the tautology is vacuous, but not false.
So saying RM&NS is a tautology doesn't make it false or keep it from being a framework for doing science, it just means that it doesn't add anything to our body of knowledge without further field and lab work.
-Neil
[This message has been edited by NeilUnreal, 07-21-2003]

  
Syamsu 
Suspended Member (Idle past 5589 days)
Posts: 1914
From: amsterdam
Joined: 05-19-2002


Message 10 of 130 (46716)
07-21-2003 2:27 PM
Reply to: Message 8 by Admin
07-21-2003 1:39 PM


Uh you are mistaken, heritability of zero is part of the standard definition of Natural Selection, not my redefinition. I referenced a website about it before with the title something like: why is heritability generally zero. You can also see in the glossary of this site that fitness and heritability is relative to another variant.
regards,
Mohammad Nor Syamsu

This message is a reply to:
 Message 8 by Admin, posted 07-21-2003 1:39 PM Admin has replied

Replies to this message:
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 Message 15 by Admin, posted 07-21-2003 4:03 PM Syamsu has not replied

  
mark24
Member (Idle past 5195 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 11 of 130 (46717)
07-21-2003 2:34 PM
Reply to: Message 10 by Syamsu
07-21-2003 2:27 PM


Syamsu,
Uh you are mistaken, heritability of zero is part of the standard definition of Natural Selection, not my redefinition.
I think therein lies the problem. Natural selection invokes fitness, & fitness, biologically speaking, means the relative ability to procreate. Procreation involves heritability, non? Heritability is therefore implicit to natural selection.
If heritability isn't a part of NS, then why experimentally is absolutely vital?
Mark
------------------
Occam's razor is not for shaving with.
[This message has been edited by mark24, 07-21-2003]
[This message has been edited by mark24, 07-21-2003]

This message is a reply to:
 Message 10 by Syamsu, posted 07-21-2003 2:27 PM Syamsu has not replied

  
JustinC
Member (Idle past 4843 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 12 of 130 (46724)
07-21-2003 3:22 PM
Reply to: Message 2 by crashfrog
07-21-2003 2:01 AM


quote:
I believe that is exactly how it is currently defined. Fitness is a measure of the reproductive success of an individual
If we changed "survival" to mean reproductive success, so that the phrase was "reproductive success of the fittest", would that still make sense? It seems to me that it would. But it would seem to become a tautology, since fitness is a measure of reproductive success.
Bringing the subject down to the individual level, as opposed to lineages, how can we measure fitness? Can it be just from an engineering perspective, and some designs are a priori better suited for certain environments?
So the phrase would be "reproductive success of the better engineered for a particular environment." This seems to make sense and seems how it is pragmatically used in evolutionary biology.
I stated this definition to a pseudo-creationist friend of mine, and he asked "Why do the better engineered have reproductive success?" Is this a valid question? Does the best engineered just survive a priori? Should the answer be "Because they are best engineered to reproduce?" The phrase would now be "reproductive success of the best engineered for reproductive success." This seems tautologous, but is it?
JustinC
[This message has been edited by JustinCy, 07-21-2003]

This message is a reply to:
 Message 2 by crashfrog, posted 07-21-2003 2:01 AM crashfrog has not replied

Replies to this message:
 Message 14 by MrHambre, posted 07-21-2003 3:46 PM JustinC has replied

  
JustinC
Member (Idle past 4843 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 13 of 130 (46727)
07-21-2003 3:44 PM
Reply to: Message 5 by MrHambre
07-21-2003 10:25 AM


quote:
Natural selection is not a tautology, but it can be described in a way that makes it sound like circular reasoning. Yes, if 'fitness' refers to the ability to reproduce most effectively, then the fittest organisms in a population will indeed leave the most offspring. That's not saying anything about fitness.
I understand that in most situations, the interaction between the environment and organism are too complex to make any accurate prediction about what is fit.
But I'm talking about a theoretical framework for fitness. Can it be described as reproductive success? Or does there have to be an independent criterion for fitness not involving reproductive success, such as in engineering.
I guess you can say that a replicating molecule has a purpose, which is to replicate. And then, from an engineerinig perspective, there is a best way to replicate in a given environment. And this way isn't arbitrary is it? Once something has a purpose, there is a best way to actuate that purpose isn't there? And since our purpose is reproductive success, the best engineered to reproductively succeed will reproductively succeed. Is this tautologous?
Would the analogy be something like:
"Easier pounding of the nail by the best hammer." The hammers purpose would be to pound in nails. And from an engineering perspective, there would be an absolute best way (multiple ways maybe) to pound in nails. So it's saying the best engineered to pound in nails will pound in nails easier. Does that make sense?
So is it tautologous to say to say, "The best engineered to perform action x, will perform action x the best." It seems like a truism, but it also seems like it makes predictions. I mean, if I have 2 different hammers, I'd be able to know which one would be best engineered and pound in nails easier, right?
I don't know, any thoughts?
JustinC
Sorry if I sound like I'm rambling, i'm trying to work these ideas out in my head. I'm not saying anything definatively either, I'm just tentatively expressing some things.

This message is a reply to:
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MrHambre
Member (Idle past 1392 days)
Posts: 1495
From: Framingham, MA, USA
Joined: 06-23-2003


Message 14 of 130 (46728)
07-21-2003 3:46 PM
Reply to: Message 12 by JustinC
07-21-2003 3:22 PM


Like I said, the definition of natural selection can be stated in a way that is circular. I'm glad you all agree with me. Too bad I didn't make myself clear concerning the definition of fitness.
I'll accept that fitness is only meaningful in terms of reproductive success. The meteor hurtling toward the Yucatan was the missing variable in the fitness equation that meant the difference between the fitness of most dinosaurs and their extinction. In contrast, the humble peacock carries plumage that no one would consider advantageous in the fitness equation except for the fact that peahens are attracted to it. An organism can be not-well-adapted to its environment and still win the reproductive lottery.
Fitness can't be defined in terms of an objective set of traits, however. What makes a cactus fit is not the same thing that determines fitness in a walrus. We have to examine each organism in its fitness landscape to discern what determined its fitness, which traits were selected for at the expense of so many others.
------------------
Quien busca, halla

This message is a reply to:
 Message 12 by JustinC, posted 07-21-2003 3:22 PM JustinC has replied

Replies to this message:
 Message 16 by JustinC, posted 07-21-2003 4:24 PM MrHambre has replied

  
Admin
Director
Posts: 12995
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.3


Message 15 of 130 (46729)
07-21-2003 4:03 PM
Reply to: Message 10 by Syamsu
07-21-2003 2:27 PM


Hi Syamsu,
While under many circumstances board administration is desirous that members understand why a request is made, your past history indicates how unlikely it is that you would accept any explanation. I am therefore informing you that we are not having a discussion, and that you have two choices. You can honor the administrative request, or you can ignore it and have your posting privileges suspended.
Just to be absolutely clear, any further attempts to transform an administrative request into a discussion will result in suspension. Any further discussion by you in this thread or in any other existing thread outside of the Free For All forum on your particular views on variation and NS will also result in suspension. You may discuss this view and your views on social Darwinism only in threads that you open, or in threads that other people open specific to your views on these topics, but no more than one thread open per topic at a time. Or you may post in the unmoderated Free For All forum.
------------------
--Percy
   EvC Forum Administrator

This message is a reply to:
 Message 10 by Syamsu, posted 07-21-2003 2:27 PM Syamsu has not replied

  
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