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Author Topic:   How can evolution explain body symmetry?
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 9 of 284 (111686)
05-31-2004 12:06 AM
Reply to: Message 6 by CrackerJack
05-30-2004 11:26 PM


quote:
Certainly there would have been at least one asymmetrical mutation in the history of the evolution of man which was beneficial enough to have been retained or even if not beneficial would have piggybacked on a beneficial mutation being propagated.
Language in humans evolved to be processed in the left hemisphere of the brain.
This is an asymmetry that is shared by nearly all humans today.
Your premise is shown to be false.
quote:
But the fact that there isn't any is very strong evidence that evolution never happened.
That is an unwarranted, giant non sequitur.
I found the following information in about 2 minutes after doing a quick google on "asymmetrical animals".
Maybe you forgot to try to find out if there actually were asymmetries before declaring that there weren't?
quote:
If extra digits are such a common result of mutation,
It's not all that common.
quote:
we should see all sorts of animals with differences in the number of digits between their left and right side.
Why would this trait be selected for?
We do see some selection for polydactylism in cats, because more digits with claws on them results in better ability to catch prey, as long as the number of "extra" toes doesn't encumber or endanger the cat before it can reproduce.
quote:
So the fact that we do not see many such asymmetrical features on generally symmetrical animals indicates that either not enough time has passed since they were created / came into being, or there has never been enough geographical isolation from the main population for such mutations to propagate.
But we do see such creatures.
Crabs and lobsters tend to have one claw that is larger than the other. In some crabs, this is extremely pronounced, which is used to communicate with other crabs.
Flounder and other flat fish are quite asymmetrical, because they have evolved to lie flat on the ocean floor.
Sponges have no axis in their body plans.
Snail shells coil either to the right of left.
One ear on an owl is set higher than the other so they can pinpoint sounds better.
A bit more can be found here:
BBC - 404: Not Found
This message has been edited by schrafinator, 05-30-2004 11:14 PM

This message is a reply to:
 Message 6 by CrackerJack, posted 05-30-2004 11:26 PM CrackerJack has replied

Replies to this message:
 Message 12 by crashfrog, posted 05-31-2004 2:43 AM nator has not replied
 Message 13 by CrackerJack, posted 05-31-2004 5:50 AM nator has replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 10 of 284 (111687)
05-31-2004 12:13 AM
Reply to: Message 8 by CrackerJack
05-30-2004 11:50 PM


What is so special about symmetrical mutations that makes them beneficial and asymmetrical mutations not?
Vertebrates all evolved from water dwelling, swimming creatures, and there is VERY good reason for a swimming creature to be symmetrical. Once the symmetry is established, why do you expect it to be abandoned so much? And of course, when there's a good reason, it is abandoned (see the pics in previous post).

This message is a reply to:
 Message 8 by CrackerJack, posted 05-30-2004 11:50 PM CrackerJack has replied

Replies to this message:
 Message 14 by CrackerJack, posted 05-31-2004 6:00 AM nator has replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 24 of 284 (111777)
05-31-2004 10:41 AM
Reply to: Message 13 by CrackerJack
05-31-2004 5:50 AM


quote:
Now I totally agree with you that the internal body is not completely symmetrical. Why do you suppose it is that evolution chose such perfect symmetry of the external human body and of most creatures, while choosing an asymmetrical internal body? It doesn't make any sense to me why evolution is supposedly so random, yet seems to be so selective in this case as if it is some designer doing the selecting.
1) Many creatures are not extrenally symmetrical, as I illustrated.
2) Why do you discount internal asymmetry as evidence of evolution producing asymmetry? Internal structures evolve in exactly the same way as external, so it makes no sense for you to treat them differently.
3) Evolution has been shown to proceed by random processes combined with selection, but the selection is done by the environment. No intelligent "designer" needed.
quote:
I know of two different cases of extra digits, so I would say it is fairly common, based on my observations, but whatever.
No offense, but your own personal observations are statistically meaningless.
We call such information "anecdotal evidence", and it is quite unreliable, because your sample size is tiny and non-random.
quote:
I have personally only seen mutations that were asymmetrical and none that were symmetrical.
I have a mutation that caused both of my lower wisdom teeth to never develop, and that was symmetrical.
A woman my husband knew in high school has corckscrew-like pinky fingers and that is symmetrical.
Polydactylism in cats is symmetrical.
quote:
But being I haven't made any scientific analysis of what are the probabilities of each type, I can't make any definite statement about that. The point is that asymmetric mutations are certainly not rare when compared to mutations in general.
You have made a factal claim here. Please provide reliable evidence to support it.
quote:
First, I didn't say that there weren't any asymmetrical features in any animals. I was referring to man, and a large group (majority) of animals that are symmetrical.
If by "animals", you mean "vertebrates", I have already explained that all vertebrates evolved from sea-dwelling creatures, so therefore follow the same basic body plan.
quote:
The fact that such a large class of creatures exhibit external symmetry, without any significant deviation, shows that at no point in their history were there any asymmetries, or else somehow they were culled out.
Exactly, but not in all cases, as my photographs showed you.
quote:
The fact that you came up with a few examples of asymmetries just proves my point that there is no reason why non-detrimental asymmetries should not occur as part of evolution.
Right. All the asymmetries I showed are adaptive.
You seem to think that non-adaptive assymmetries (you limit your requirement to only in humans and only external, for some strange reason) should be widespread in a population.
Evolution doesn't make that prediction.
quote:
But in general they do not. Why are there a few animals that exhibit clear asymmetries while the majority don't?
All animals exhibit clear assymetry, you just want to ignore the internal ones.
Why do you insist that we ignore internal asymmetry?
quote:
Even by your own claim, you say that the asymmetries in these few examples are the result of the evolutionary process. Thus, by your claim there should not exist any evolutionary process that culls out all asymmetric mutations because such mutations are clearly visible in the examples you brought up.
That is exactly what I am saying.
There are, however, evolutionary pressures to cull out most asymmetries.
quote:
So what happened to all the asymmetric mutations that occurred throughout the history of the evolution of man?
We still have them.
They are mostly internal.
Why do you ignore them?
As for external symmetry in humans, it has been empirically shown that symmetry is strongly sexually selected. IOW, asymmetry reduces a human's chance of mating.
quote:
Why can't we see them? If evolution isn't deselecting them, then what is? Why are humans left with only the symmetrical ones?
1) Evolution does select them out, which is why we don't see them.
2) We have plenty of asymmetries, they are just internal. Why don't they count to you?
quote:
Trying to say that EVERY SINGLE mutation that has led to modern man/animals was beneficial, and that each mutation becomes dominant in the population before the next beneficial mutation can occur is totally absurd.
You're right, it is absurd.
That's why the above is not what evolution says.
There is nothing in the ToE which requires only one beneficial mutation to become dominant in a population before another occurs.
If this were true, the entire human population would be genetically identical.
quote:
Thus, even if no positive asymmetrical mutations ever occurred in the evolution of man, you would expect to to have some retained due to this piggybacking effect.
But they are here.
Humans are FUNDAMENTALLY asymmetrical in nearly all respects EXCEPT for basic body plan, alterations to which are likely to strongly negatively affect either locomotion, sexual attractiveness, or both.

This message is a reply to:
 Message 13 by CrackerJack, posted 05-31-2004 5:50 AM CrackerJack has replied

Replies to this message:
 Message 34 by CrackerJack, posted 06-01-2004 6:27 AM nator has replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 25 of 284 (111778)
05-31-2004 10:48 AM
Reply to: Message 14 by CrackerJack
05-31-2004 6:00 AM


quote:
You make a very good point about swimming sea creatures. If evolution was true, that would be a very good reason why symmetry was selected in those creatures. But the migration from sea to land happened long ago, yet the symmetry still exists with very little deviation in spite of huge evolutionary change in the creatures. If very little change had occurred since the start of land creatures, you would have a very good point. But given all the time, and all the multitude of mutatations, I don't see the significance of your point with relation to land creatures.
But once you set up embryonic development in which all vertebrates are symmetrical in their basic body plan, how long do you think it should take to change it, particularly since there is no great evolutionary pressure to be asymmetrical?
Furthermore, creatures ARE fundamentally asymmetrical, except for basic body plan, alterations to which may detrimentally affect sexual attractiveness and locomotion.

This message is a reply to:
 Message 14 by CrackerJack, posted 05-31-2004 6:00 AM CrackerJack has replied

Replies to this message:
 Message 35 by CrackerJack, posted 06-01-2004 6:28 AM nator has not replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 27 of 284 (111782)
05-31-2004 11:02 AM
Reply to: Message 16 by CrackerJack
05-31-2004 6:39 AM


Re: Once more slowly
quote:
Non-advantageous mutations should very often occur piggybacking on advantageous ones.
Why should this happen "very often"?
Also, please define "very often"; how often is "very often?".
quote:
So there seems to be a definite preference for external symmetry, and a much less preference for internal symmetry. Now can you offer some explanation for this difference between internal and external? Why would symmetry be so much more preferred for the external body and not the internal?
Alterations to the external body may reduce sexual attractiveness and may impede locomotion.
quote:
Mutations don't prefer symmetry or asymmetry. They are random. But the evidence of existing life forms shows a high degree of preference for external symmetry. Thus evolution via mutations cannot be adequately explained in light of such obvious symmetry.
Actually, mutations affecting basic body plan do strongly tend to affect the individually symmetrically, because that is how embryonic development occurs.
quote:
Yes, plants do not exhibit the same degree of symmetry as found in animals. But I never mentioned plants in my post and fail to see what that has to do with anything being plants and animals are totally different life forms.
No, plants and animals are not fundamentally different life forms.
Fundamentally, they are the same.
The same system of DNA and RNA is found in both plants and animals.
Why does it matter, anyway?
quote:
As I already mentioned in another post, your few examples of asymmetry in an otherwise symmetrical world just proves the existence of asymmetrical mutations which flies in the face of the evolution of symmetrical creatures.
NO IT DOESN'T!
Evolution does not predict that every single creature be symmetrical.
Nor does it predict that every single creature be asymmetrical.
It predicts that populations will, over time, adapt to their environments or go extinct.

This message is a reply to:
 Message 16 by CrackerJack, posted 05-31-2004 6:39 AM CrackerJack has replied

Replies to this message:
 Message 37 by CrackerJack, posted 06-01-2004 6:32 AM nator has replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 28 of 284 (111786)
05-31-2004 11:06 AM
Reply to: Message 21 by CrackerJack
05-31-2004 9:12 AM


quote:
Second, who says even a perfect designer would create something perfectly symmetrical? In his mind, something less than perfectly symmetrical might be exactly what he intended. If you don't know the designer, how can you guess at what his intentions were?
If you can't make any testable predictions about how the designer might design something, the ID is useless as science.
Also, you have been saying all along that suchandsuch is evidence for a designer, but now you say it is impossible to know what or how the designer designed anything.
Which is it? Do you know, or is it impossible to know?
This message has been edited by schrafinator, 05-31-2004 10:09 AM

This message is a reply to:
 Message 21 by CrackerJack, posted 05-31-2004 9:12 AM CrackerJack has replied

Replies to this message:
 Message 39 by CrackerJack, posted 06-01-2004 6:33 AM nator has replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 29 of 284 (111787)
05-31-2004 11:12 AM
Reply to: Message 21 by CrackerJack
05-31-2004 9:12 AM


quote:
Point 1 does explain the initial symmetry of swimming sea creatures, but fails to address why the symmetry has remained in spite of a huge span of time over which asymmetrical mutations should have been common and long ago changed much of the symmetry. Point 2 I will address in response to your next quote.
Symmetry is useful for walking on land, too.
Try walking with one leg shorter than the other.
Also, Why do you think that asymmetrical mutations should have become dominant long ago if they are not adaptive?

This message is a reply to:
 Message 21 by CrackerJack, posted 05-31-2004 9:12 AM CrackerJack has replied

Replies to this message:
 Message 31 by jar, posted 05-31-2004 11:23 AM nator has not replied
 Message 40 by CrackerJack, posted 06-01-2004 6:34 AM nator has not replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 30 of 284 (111789)
05-31-2004 11:22 AM
Reply to: Message 21 by CrackerJack
05-31-2004 9:12 AM


quote:
Do you mean to say that if some animal had a nose on the side of it's head, it couldn't walk?
No, but if it had one leg a lot shorter than the others, it would have a pretty hard time of it.
quote:
Or if I have one extra digit or one less digit on my hand, that means I can't walk?
No, but it may impede your ability to grasp and hold things in your hand, like food, weapons, tools or prey. Hands, BTW, are unique to certain primates. They are an extremely recent evolutionary development.
Potential mates would probably be less likely to be attracted to you due to your birth defect, too.
quote:
Some huge asymmetrical appendage might create an imbalance, but other than that I fail to see how an asymmetrical mutation would cause a creature to not walk. Please explain.
One leg is shorter than the others.
One foot is larger than the others.
Your big toe is tiny on one foot and big on the other.
You are under some mistaken impression that a mutation has to cause a creature to not be able to walk at all to be tetrimental.
My husband is bow legged and flat footed, which is fine now because he is an academic, but a million years ago, on the savannah, he would be at a pretty big disadvantage.

This message is a reply to:
 Message 21 by CrackerJack, posted 05-31-2004 9:12 AM CrackerJack has replied

Replies to this message:
 Message 42 by CrackerJack, posted 06-01-2004 6:47 AM nator has not replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 59 of 284 (112179)
06-01-2004 6:55 PM
Reply to: Message 34 by CrackerJack
06-01-2004 6:27 AM


quote:
When you look at the animal world as a whole, you see external symmetry as the norm, not as the exception.
Right.
This is because we evolved from aquatic creatures in which symmetry is very advantageous. Symmetry continues to be advantageous in MOST cases.
quote:
If internal and external structures evolve in exactly the same way, then there should be lots of asymmetry in both.
Why?
You can't see the inside of other creatures, so sexual selection in favor of internal symmetry cannot happen.
quote:
Being there isn't, evolution should be discounted because as of yet nobody has given a good enough explanation to account for such a high degree of external symmetry. And the sexual selection argument doesn't cut the mustard as I've already shown.
You have shown it? Where?
quote:
And there is no need in the environment for such a high degree of external symmetry in land creatures,
Really?
Are you typically sexually attracted to people with significant facial deformities?
That makes you pretty rare.
quote:
so no need to deselect asymmetry unless it negatively impacts locomotion due to an imbalance or some other such effect. Proof has already been provided of limited asymmetry, so why is it so selective and not widespread?
When your basic body plan is externally symmetrical from embryonic development, and external symmetry is sexually selected for, why do you expect asymmetry to become widespread at all?
quote:
Ok, I have done some research today on symmetrical vs. asymmetrical mutations and yes there are a fair number of symmetrical mutations as you have pointed out.
At last, you are doing some research.
Now, perhaps you might consider doing all of your research before you make exterme claims instead of after.
quote:
But polydactylism in cats is not always symmetrical.
So?
The ToE doesn't say that it has to be.
quote:
In general, some mutations are symmetrical, and some are not. So unless someone can provide some actual scientific data on what is the ratio between the two, we can't really say anything more than both types are well known to occur.
That's what we've been saying all along, you know.
quote:
No, I don't limit it to just humans. If evolution were true, there should be some probability that some percent of all mutations that are retained will be clearly asymmetrical.
Why?
quote:
Statistically, most asymmetries (not including those that negatively impact the species) should have stopped being deselected once fish became land animals.
Why?
quote:
Being man is claimed to be a descendant of the original land animal, that means that some very early ancestor should have some noticeable asymmetric feature and all descendants from that creature, including man, should exhibit that feature.
Why?
Where is the selection pressure for asymmetry?
quote:
Along with it, many other asymmetries should have been picked up along the way, and the end result should be a wide range of asymmetries across the entire spectrum of the animal kingdom.
Why?
quote:
If evolution was true, I would expect just about every land creature to exhibit some clearly visible external asymmetry.
Why?
Where is the selection pressure for asymmetry?
quote:
I'm just saying that if evolution is creating internal asymmetry, it should also be creating external asymmetry. There is no reason for it to be so selective.
SEXUAL SELECTION and LOCOMOTION selects in favor of external symmetry, as well as our basic body plans being derived from sea-dwelling creatures in which external symmetry was also highly advantageous.
quote:
Agreed that in humans, a new asymmetry would be a disadvantage.
Why?
It might not be a disadvantage at all.
In fact, for it to become fixed in a population, it would have to tend to be advantageous in some way, to some population.
quote:
But if all humans had the same asymmetrical feature, it would be considered normal and not deselected.
Since we already sexually select FOR external symmetry, an obvious external asymmetry is not likely to become widespread in the first place.
quote:
Lower animals are not capable of the same sort of reasoning and inspection that a human is.
Actually, our ability to reason is why people with facial deformities and other external asymmetries are able to get mates.
Unlike animals, we are able to be attracted to a personality and overlook the physical.
Anyway, why do you think that animals don't reject deformed offspring or potential mates? My friend's cat just had kittens, and there was a malformed one in the litter. The mother ate it.
quote:
So some distant ancestor of man should have had an external asymmetrical mutation that was retained and considered normal and thus not sexually deselected.
Why?
Why would it be selected for in the first place?
quote:
What do you mean by "most"?
The majority of selective pressures favor external symmetry. A minority do not.
quote:
And by what means (other than what has already been mentioned) are they culled out?
They are less likely to reproduce, thus they do not pass on the mutation.
quote:
Many mutations, symmetrical or asymmetrical, will create a big disadvantage and should obviously be culled.
They are, in the form of failed implantation, reabsorbed, miscarried, and stillborn offspring, etc.
quote:
Asymmetrical mutations that create one longer leg than the other are obviously going to be culled. But would a long ear lober be culled?
No, that's why we see them today.
quote:
What about all the positive mutations that have occurred. Take opposable thumbs for instance. Everyone agrees that they are a huge advantage for humans. What if an early ancestor of man evolved an opposable thumb on just one hand and not the other, would that be culled because it was a disadvantage? Of course not.
The opposable thumb isn't human in origin. We got that from our primate ancestors.
Anyhow, haven't you been reading what we have been telling you about how embryonic development occurs?
quote:
It would be retained. Somewhere along the line, some of the advantageous mutations should have been asymmetrical and retained.
Like what?
quote:
Why does evolution select them out?
Because they are actively selected against due to our preference for external symmetry in mates, mostly.
If they conferred an advantage in some way, though, we'd still have them.
quote:
The sexual deselection argument doesn't cut it as I've already shown.
I haven't seen this. Where have you done this?
Did you know that there are many studies which show that symmetry of facial features is the most important factor in someone finding a face attractive?
quote:
Please provide a reason that applies to ALL externally symmetrical animals. Why is it being culled out in blind animals? How can lower level animals count and determine an uneven number of digits between the left and right?
Don't be silly. You don't have to see and you don't have to be able to count to tell if another of your species is symmetrical or not.
And, symmetry is not as important in other creature's sexual habits as ours, anyway.

This message is a reply to:
 Message 34 by CrackerJack, posted 06-01-2004 6:27 AM CrackerJack has not replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 60 of 284 (112184)
06-01-2004 7:07 PM
Reply to: Message 39 by CrackerJack
06-01-2004 6:33 AM


quote:
If life as we know it didn't come about by evolution, and it didn't come about by an intelligent designer, then by what means was it created?
If you reject all evidence for evolution (of which there is a VERY GREAT DEAL more that the tiny bit we have been discussing here), then you have to explain what we see with another scientific theory.
That theory must have positive evidence to support it, make testable predictions, and be falsifiable.
quote:
Those are the only two possibilities I can think of, and being evolution is ruled out in my mind due to the reasons I've explained, I assume it was an intelligent designer. If you can show another way by which we were created I'd be glad to entertain your idea.
You cannot make a scientific claim based upon a lack of evidence.
Nor can you make a scientific claim based upon another theory's faults or shortcomings.
Nor can you make an Argument from Personal Incredulity.
Nor can you make a God of the Gaps argument.
OK, you CAN make all of these claims and arguments, but none of them are valid arguments.
Here is a question for you...
How can we tell the difference between an Intelligently Designed system and a natural one that we;
1) don't currently understand but may in the future, and/or
2) may not ever understand?

This message is a reply to:
 Message 39 by CrackerJack, posted 06-01-2004 6:33 AM CrackerJack has not replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 62 of 284 (112243)
06-01-2004 9:20 PM
Reply to: Message 37 by CrackerJack
06-01-2004 6:32 AM


Re: Once more slowly
quote:
To define precisely how often it would occur, I would have to collect data on what is the ratio between symmetrical and asymmetrical mutations, then we have to decide on what the mutation rate is when evolution is occurring and do some calculations. Being that current biologists are tending towards rapid mutations in a short time, followed by long periods of stability, I assume the mutation rates they are expecting during the evolutionary steps are quite high. The higher the mutation rate, the more frequent you will see multiple mutations piggybacking on the main mutation(s) responsible for the step. Being we don't observe this type of mutation happening (at least not quick enough to measure), we have no way of knowing what exactly is the mutation rate at the point of these evolutionary steps. Thus no way of calculating it precisely.
You seem to be talking about Puntuated Equilibrium, but doing so inaccurately.
PE has nothing to do with mutation rates.
Mutation rates are more or less constant, barring exposure to chemical mutagens, etc.
You are also under the mistaken impression that any, or every, given mutation is likely to spread throughout the population as a whole.
Only those mutations that confer a strong adaptive benefit are likely to spred through a population.
quote:
From an evolutionary perspective and from your perspective they may be fundamentally the same, but they are certainly not the same from mine.
Since we are discussing science, your personal perspective is irrelevant.
quote:
But it really doesn't matter as you say. I was referring to animal symmetry, and not to plants or microscopic organisms and I was not the one who brought up plants.
But you are the one that is making a genetic, evolutionary distinction between plants and animals where there isn't one.
Plant and animal DNA and RNA are made of exactly the same molecules (A,G,T,C), and mutations and meiosis and mitosis happens the same way.
The reason we see more asymmetry in plants compared to animals is because they do not locomote and they don't sexually select.
Why do you refuse to consider plant evolution other than because it weakens your argument, just like your refusal to consider internal asymmetry in animals weakens your argument.
What you are doing is ignoring 99% of Earth's life forms by considering only the external appearance of land animals.
Most life is in the ocean, most land life is not animal.
Furthermore, you are even ignoring more than 50% of the bodies of those land animals because you refuse to consider internal asymmetry.
quote:
Then why do you and everyone else keep harping on selection for symmetry based on sexual attraction and locomotion?
Because for the VERY narrow slice of life you're talking about; the skeletal plan and external surface of land vertebrates; these are known to be important selection pressures. These do NOT hold universally. Locomotion is not an important pressure for non-motile organisms (sponges and corals, plants, fungi), and not all life exhibits sexual selection for symmetry. Both of these are important for all or nearly all land vertebrates, however.
quote:
On the one hand you are saying that evolution is selecting for symmetry for these reasons, and on the other hand saying it is selecting for the environment.
Sexual selection and locomotion are the environment.
I think maybe you might want to read a basic explanation of Evolutionary Biology, such as the one found here:
http://www.talkorigins.org/faqs/faq-intro-to-biology.html
quote:
Well you are trying to take both sides of the fence and it doesn't work that way. Pick one side or the other and stick to it.
That's rich!
You have basically claimed that every example of symmetry AND every example of asymmetry proves your point.
quote:
Your showing of these asymmetrical features proves that sexual attraction does not always work.
I never said it did in every single case.
Visual symmetry is not important in ALL animals for sexual selection, just like not all femalse are attracted to vivid external coloring in the males.
Symmetry is important in humans, however.
quote:
If it didn't work in these cases, you specified, then we first should assume it never works unless it can be proven otherwise.
It has been shown in many animals.
Why do you require that it be all?
quote:
It is certainly proven in humans that it can be a factor, but I have seen no evidence that it is effective in any of the lower life forms.
Sexual selection is one of at least three reasons why symmetry may be maintained.
We know it's true in some cases, and we don't know if it is true in other cases. It is a hypothesis that can be tested, however, unlike the Intelligent Desihner idea, which cannot be tested at all.

This message is a reply to:
 Message 37 by CrackerJack, posted 06-01-2004 6:32 AM CrackerJack has not replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 70 of 284 (113563)
06-08-2004 9:09 AM


There's a very good chance that CrackerJack has run away.
Too bad, he seemed pretty smart.
Hey, B2P, keeping track of how many Creationists run away because they wish to remain ignorant of the evidence?

Replies to this message:
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nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 216 of 284 (227052)
07-28-2005 11:02 AM
Reply to: Message 205 by iano
07-28-2005 7:11 AM


Re: Darwin revisited?
quote:
There exists a mass of evidence to indicate that indoctrination has occured: folk are told Evolution is a fact for from their formative years upwards, long before they have been equipped (if ever they truly could be) to establish the facts for themselves. Note: whether the indoctrination is ultimately true or false matters not. It's still indoctrination.
There exists a mass of evidence to indicate that indoctrination has occured: folk are told that the Earth is a sphere is a fact for from their formative years upwards, long before they have been equipped (if ever they truly could be) to establish the facts for themselves. Note: whether the indoctrination is ultimately true or false matters not. It's still indoctrination.
quote:
Maybe in going public, the ID-ers are taking a leaf out of Darwins book. It worked pretty well for him!!
Tell me, just what do you think the practice of science was like in Darwin's day?
What was the leading professional journal, for example? What were the PhD requirements?

This message is a reply to:
 Message 205 by iano, posted 07-28-2005 7:11 AM iano has not replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 239 of 284 (227247)
07-29-2005 7:11 AM
Reply to: Message 224 by iano
07-28-2005 3:00 PM


Re: In Doctor, In Nation.
quote:
It could well happen in other areas of science - although I can't think of one where the indoctrination begins at such an early age in such a socially widespread manner.
How about children being indoctrinated in the idea that the Earth is a sphere long before they have the ability to examine the data for themselves?
quote:
He's a physics lecturer and while knowing a litte, is not immersed in the field (he's rooted on the fence of "I don't know" at the moment).
What is a physics "lecturer"?
Does he have a degree in Physics?
quote:
And it works a lot on those who are immersed in the subject. There are geoligists, paleantologists, anatomists, biochemists etc who are qualified and experienced yet don't believe in evolution.
Almost without fail, such qualified people in those fields who do not accept the evidence for Evolution do so upon a religious, not scientific, basis.
Scientific advancement progresses through consensus. For an idea to become widely accepted, it must survive many repeated tests by many disinterested parties. IOW, it has to be useful, and it has to be consistent.
The theory of evolution has survived, and so we accept it tentatively as the best current explanation of the change in alleles in populations over time.

This message is a reply to:
 Message 224 by iano, posted 07-28-2005 3:00 PM iano has not replied

  
nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 240 of 284 (227248)
07-29-2005 7:16 AM
Reply to: Message 234 by iano
07-28-2005 5:23 PM


Re: A weighty issue...
quote:
I asked you to elaborate because I didn't know whether Gravity was a simple theory and you were heaving back the hammer on an irreducibly complex mousetrap - with me as the mouse, or whether Gravity is in fact complex and much argued.
Your father is a physics lecturer and he hasn't taught you anything about gravity?
How long, exactly, has your father been studying Physics?

This message is a reply to:
 Message 234 by iano, posted 07-28-2005 5:23 PM iano has not replied

  
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