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Author Topic:   Has natural selection really been tested and verified?
Granny Magda
Member
Posts: 2462
From: UK
Joined: 11-12-2007
Member Rating: 4.0


(1)
Message 136 of 302 (537095)
11-26-2009 8:00 PM
Reply to: Message 134 by Bolder-dash
11-26-2009 6:59 PM


Re: Back to Basics
Look, all I'm saying is that you didn't ask about RM. You say;
That is completely false. Please reread my opening post.
Okay BD, let's take a look at your OP;
Bolder-dash writes:
I read recently where an editor of Discovery Magazine stated that Darwin provided a testable mechanism for evolutionary change, and as such it has stood up to the rigors of such testing.
I am not so sure that this is true. Can people point to tests that have verified that natural selection causes evolutionary change? What tests have they conducted? Do these tests accurately mimic the real world?
I would like to stipulate that talking about bacteria (in any form) does not qualify as any type of test, because ultimately we must be taking sexual reproduction, where choices are being made into account-so bacteria is out.
Ok, so what are these tests which prove (or even provide solid evidence for) natural selection is the driver of evolutionary change?
I have bolded the references to NS. I would have bolded the references to RM as well, but there aren't any.
As written, your OP asks about the role of NS in causing evolutionary change. You make no mention of RM. That is why people are talking about NS and it is why we are surprised at your insistence on talking about RM.
Topics here at EvC are deliberately kept tightly focussed. This is done to avoid topic sprawl. Evolution, viewed in its entirety is a big, big subject. Many brilliant people have devoted a lifetime to understanding evolution and still there are countless aspects where we still have much to learn. A thread that took all of evolutionary change as its topic would have no focus. Had you worded your OP to say "I would like to discuss all aspects of evolution; have they been tested?", it would most likely not have been promoted. That's just how things are done around here; we find that tightly focussed topics work better in promoting productive discussion.
Hopefully, this might help you understand why so many people here are taking umbrage at what they probably see as an attempt by you to move the goalposts.
I mentioned "evolutioary change" three different times.
You mentioned RM zero times. You asked about the role of NS in evolutionary change. That's why you have been getting answers about the role of NS in evolutionary change. It's really not complicated.
Your problem seems to be that I didn't include my entire post in the title of the post. I suppose if one did that, there would be no need for a title, because the post would be the title.
My problem is that you didn't ask about the role of RM in evolutionary change. You asked about the role of NS in evolutionary change. Then, you started throwing a tantrum that no-one had addressed RM, the subject you didn't ask about. You didn't ask about genetic drift or the founder effect either; are you going to complain that no-one has addressed them?
Granny writes:
I don't think that anyone is disputing that. To discuss evolution as a whole one must discuss both natural selection and random mutation.
Bolder-dash writes:
So can I now at least pin you down to this point?
What, the point that I clearly said no-one was disputing? Given that we've hardly spoken on this thread, you haven't "pinned me down" on anything. I said that evolution, considered in its entirety, includes both NS and RM. It includes much more besides. A cursory glance at any biology text book would be enough to confirm this, so don't you go acting as though you have won some kind of concession here.
Evolution involves both natural selection and random mutation. You didn't ask about the whole of evolution though. You asked about the role of NS in evolution.
No-one is trying to tell you that you can't ask or talk about RM. What we are telling you is that it's a bit rich to ask a question about NS and then complain that we haven't addressed RM. That makes no sense and only serves to make you look foolish.
Mutate and Survive
Edited by Granny Magda, : Grammar, style.

"A curious aspect of the theory of evolution is that everybody thinks he understands it." - Jacques Monod

This message is a reply to:
 Message 134 by Bolder-dash, posted 11-26-2009 6:59 PM Bolder-dash has replied

Replies to this message:
 Message 156 by Bolder-dash, posted 11-27-2009 8:16 AM Granny Magda has replied

ZenMonkey
Member (Idle past 4510 days)
Posts: 428
From: Portland, OR USA
Joined: 09-25-2009


Message 137 of 302 (537096)
11-26-2009 8:12 PM
Reply to: Message 130 by Bolder-dash
11-26-2009 5:12 PM


Re: forward?
Bolder-dash writes:
Without the concept of random mutatins causing evolutionary change, we don't have evolution-and yet you don't want to discuss random mutations.
Eh, no. Go back and re-read the thread, especially Huntard's reply to you at Message 86. Natural selection is a filter. Without non-directed mutation, Natural Selection would still occur, but the results would likely be different from those we see in our particular reality. Depending on your parameters, you might or might not see the evolution of new species taking place. But Natural Selection would still act independently as a selector determining reproductive success.
How about one possibility? Here's a hypothetical example of Natural Selection resulting in hereditary change but without mutation.
Say that variation our genetic make-up was determined by the gods. Let's suppose that Zeus, Aphrodite et. al. were still around making half-human/half-god heroes and monsters with half-human/half-god DNA, while at the same time restricting the rest of us without divine parentage to stable, non-mutating DNA. Natural Selection would still work. We'd still see changes in the distribution of alleles in the population. Heroes would almost certainly have different rates of reproductive success than we mortals do. (Whether they'd be more likely to leave descendants because they're semi-divine hotties with *ahem* special powers, or less likely because killing monsters is part of the job description, would have to be determined.) But natural selection would still be an active agent. The environment would still act as filter. Changes in allele distribution would still take place. However, the nature and frequency of these changes would be Zeus-driven rather than mutation-driven. Thus, hereditary change - hereditary because the important genes come only from divine parents - without non-directed mutation.
Obviously, there are a lot of other factors to take into account. In this particular scenario the distribution of divine DNA probably wouldn't matter in the long run. Having a hero for a dad would probably do nothing to change the chances of your own reproductive success. Genetic variation would only occur by divine intervention, and since it wouldn't persist beyond the first generation, the evolution of new species would be unlikely if not impossible. Nevertheless, this somewhat far-flung example at least shows that Natural Selection and mutation are separable elements that can be considered independently.
My apologies for going off into the Land of Let's Pretend. I'm sure that I'm week in the details but at least I hope that I'm expressing the general idea that just because we'd get different results in a world that lacked non-directed mutation, that doesn't mean that non-directed mutation and Natural Selection alway have to go together.
{ABE} I also hope that this doesn't obscure the idea that in discussion evolution as a whole, it's still necessary to include both mutation and Natural Selection. The point remains that you can consider how one works without also having to discuss the other.
Edited by ZenMonkey, : Added attempt at clarification.

This message is a reply to:
 Message 130 by Bolder-dash, posted 11-26-2009 5:12 PM Bolder-dash has not replied

RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 138 of 302 (537097)
11-26-2009 8:14 PM
Reply to: Message 132 by Bolder-dash
11-26-2009 6:26 PM


Re: forward?
Hi Bolder-dash,
So will you now concede that in order to discuss evolution, we need to discuss both?
I will concede precisely what I said in my first response to you (Message 5):
quote:
Hi Bolder-dash, and welcome to the fray.
Has natural selection really been tested and verified?
Yes, in fact it has been tested and verified so many times that it has been validated to a very high degree.
There are so many observations and studies of natural selection causing a shift in the frequency of genetic traits from one generation to the next, that it is difficult not to find cases where it occurs. Are actual field studies observing the effects on natural selection in undisturbed nature, so we are not even limited to lab studies.
Also see "Natural Selection Examples" - google results
I am not so sure that this is true. Can people point to tests that have verified that natural selection causes evolutionary change? What tests have they conducted? Do these tests accurately mimic the real world?
First you need to define what you mean by "evolutionary change" - so we can see if your meaning is similar to what is used in the science of biology in general and evolution in particular.
In science "evolutionary change" means that the frequency distribution of hereditary traits is different from one generation to the next. I expect you are thinking of something more dramatic than variations on a theme changes.
Second, you need to distinguish between the observable phenomenon of natural selection as a process of life, and the theory of Natural Selection as part of an explanation for the diversity of life as we know it.
I would like to stipulate that talking about bacteria (in any form) does not qualify as any type of test, because ultimately we must be taking sexual reproduction, where choices are being made into account-so bacteria is out.
Curiously, natural selection involves survival and reproduction, such that those individuals which are more successful at surviving and reproducing will pass on more genes to the next generation than those that are less successful. It doesn't matter if reproduction is sexual or asexual.
Ok, so what are these tests which prove (or even provide solid evidence for) ...
In science - all science - nothing is proven. The best we have are highly validated theories with mountains of evidence supporting the theory and no contradictory or anomalous evidence. The best we can say is that this means that the theory is a good approximation of the truth.
Gravity fits this level of validation.
Natural selection fits this level of validation.
Thus the solid evidence available provides a sound basis for concluding that the theory is a good approximation of the truth.
... provide solid evidence for) natural selection is the driver of evolutionary change?
Natural selection is only part of the process of evolution, the change in hereditary traits in populations from generation to generation - other major contributors are mutation and genetic drift. Mutation provides new variations to the mix of hereditary traits that are then susceptible to the action of natural selection, and genetic drift is where stochastic effects (natural disasters etc) change the population that is then left for evolution by mutation and natural selection.
So, what you mean by "evolutionary change"? What do you expect to see?
Enjoy.
(color for emphasis)
You will note that from the start the issue of mutations was discussed as a necessary part of long term evolution. In other words you have forced me to concede that my original position was correct.
Or are you still equivocating on this point? In other words, its only evolution if it has both.
Except that this is still wrong.
Evolution involves a number of processes, including natural selection and mutation, and any one or any combination that results in the change in frequency of hereditary traits in breeding populations from generation to generation is evolution, by definition.
Again, I also will point you to Definition of Evolution, Message 212, for a more complete definition of evolution and the theory of evolution, where this last point is made in more detail.
Enjoy.
Edited by RAZD, : pushed submit too soon
Edited by RAZD, : bolded
Edited by RAZD, : added end P & reference

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
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This message is a reply to:
 Message 132 by Bolder-dash, posted 11-26-2009 6:26 PM Bolder-dash has not replied

Peg
Member (Idle past 4929 days)
Posts: 2703
From: melbourne, australia
Joined: 11-22-2008


Message 139 of 302 (537101)
11-27-2009 12:16 AM
Reply to: Message 100 by lyx2no
11-26-2009 8:50 AM


Re: Why?
lyx2no writes:
Natural selection will work on any variety from any source that differentially effect the reproductive success of the individual members.
ok, so If i have a baby which survives, thats natural selection taking place???

This message is a reply to:
 Message 100 by lyx2no, posted 11-26-2009 8:50 AM lyx2no has not replied

Replies to this message:
 Message 149 by Iblis, posted 11-27-2009 4:42 AM Peg has replied
 Message 165 by Parasomnium, posted 11-27-2009 12:37 PM Peg has not replied

Peg
Member (Idle past 4929 days)
Posts: 2703
From: melbourne, australia
Joined: 11-22-2008


Message 140 of 302 (537102)
11-27-2009 12:18 AM
Reply to: Message 101 by Wounded King
11-26-2009 8:50 AM


Re: Speciation
WoundedKing writes:
If for some reason the population becomes divided then genetic drift may cause these incompatible genetic traits to become fixed in different populations. In that case if they consolidated into one region again we would expect to see little if any successful breeding between the populations and we would consider them to have become distinct species.
could this happen in human populations and has it happened?

This message is a reply to:
 Message 101 by Wounded King, posted 11-26-2009 8:50 AM Wounded King has replied

Replies to this message:
 Message 147 by Wounded King, posted 11-27-2009 4:27 AM Peg has replied

Peg
Member (Idle past 4929 days)
Posts: 2703
From: melbourne, australia
Joined: 11-22-2008


Message 141 of 302 (537103)
11-27-2009 12:21 AM
Reply to: Message 103 by Huntard
11-26-2009 10:06 AM


Re: Here's mine
Huntard writes:
Natural selection is the process by which heritable traits that make it more likely for an organism to survive
whats the differnce between this and mutation?

This message is a reply to:
 Message 103 by Huntard, posted 11-26-2009 10:06 AM Huntard has replied

Replies to this message:
 Message 142 by Granny Magda, posted 11-27-2009 12:34 AM Peg has replied
 Message 144 by Huntard, posted 11-27-2009 2:05 AM Peg has not replied

Granny Magda
Member
Posts: 2462
From: UK
Joined: 11-12-2007
Member Rating: 4.0


Message 142 of 302 (537105)
11-27-2009 12:34 AM
Reply to: Message 141 by Peg
11-27-2009 12:21 AM


Re: Here's mine
Hi Peg,
Huntard writes:
Natural selection is the process by which heritable traits that make it more likely for an organism to survive
Peg writes:
whats the differnce between this and mutation?
When I read that I thought; "Probably in the part of that sentence that Peg left out.". So I went and had a look and sure enough...
Huntard writes:
...and successfully reproduce become more common in a population over successive generations.
I am at a loss as to what you thought to achieve by posting as you just did. Quote mining is like a disease with you guys.
Mutate and Survive

"A curious aspect of the theory of evolution is that everybody thinks he understands it." - Jacques Monod

This message is a reply to:
 Message 141 by Peg, posted 11-27-2009 12:21 AM Peg has replied

Replies to this message:
 Message 143 by Peg, posted 11-27-2009 1:33 AM Granny Magda has replied

Peg
Member (Idle past 4929 days)
Posts: 2703
From: melbourne, australia
Joined: 11-22-2008


Message 143 of 302 (537110)
11-27-2009 1:33 AM
Reply to: Message 142 by Granny Magda
11-27-2009 12:34 AM


Re: Here's mine
what is it with 'us'
sheesh
what is it with you?
Huntard attempted to show that mutation and natural selection are different
his sentence stated that natural selection produces 'inheritable traits'
My question, which you failed to answer, was what is the difference between these 'inheritable traits' and mutations?
If you cant answer, then dont.

This message is a reply to:
 Message 142 by Granny Magda, posted 11-27-2009 12:34 AM Granny Magda has replied

Replies to this message:
 Message 145 by Huntard, posted 11-27-2009 2:14 AM Peg has replied
 Message 146 by Granny Magda, posted 11-27-2009 2:35 AM Peg has not replied

Huntard
Member (Idle past 2295 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 144 of 302 (537113)
11-27-2009 2:05 AM
Reply to: Message 141 by Peg
11-27-2009 12:21 AM


Re: Here's mine
Peg writes:
whats the differnce between this and mutation?
Mutations are changes in DNA. NS is what is acting upon those changes, making it more ir less likely for the organism to survive. If therre were no natural selection, mutations would not be beneficiary, or detrimental.

I hunt for the truth
I am the one Orgasmatron, the outstretched grasping hand
My image is of agony, my servants rape the land
Obsequious and arrogant, clandestine and vain
Two thousand years of misery, of torture in my name
Hypocrisy made paramount, paranoia the law
My name is called religion, sadistic, sacred whore.
-Lyrics by Lemmy Kilmister of Motorhead

This message is a reply to:
 Message 141 by Peg, posted 11-27-2009 12:21 AM Peg has not replied

Huntard
Member (Idle past 2295 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 145 of 302 (537114)
11-27-2009 2:14 AM
Reply to: Message 143 by Peg
11-27-2009 1:33 AM


Re: Here's mine
Peg writes:
his sentence stated that natural selection produces 'inheritable traits'
No it doesn't. It states that it makes those heritable traits more common, not that it produces them.

I hunt for the truth
I am the one Orgasmatron, the outstretched grasping hand
My image is of agony, my servants rape the land
Obsequious and arrogant, clandestine and vain
Two thousand years of misery, of torture in my name
Hypocrisy made paramount, paranoia the law
My name is called religion, sadistic, sacred whore.
-Lyrics by Lemmy Kilmister of Motorhead

This message is a reply to:
 Message 143 by Peg, posted 11-27-2009 1:33 AM Peg has replied

Replies to this message:
 Message 148 by Peg, posted 11-27-2009 4:35 AM Huntard has replied

Granny Magda
Member
Posts: 2462
From: UK
Joined: 11-12-2007
Member Rating: 4.0


Message 146 of 302 (537116)
11-27-2009 2:35 AM
Reply to: Message 143 by Peg
11-27-2009 1:33 AM


Re: Here's mine
Look, Peg, there it's all very well you taking offence, but the fact of the matter is that you just chose to clip Huntard's quote and in doing so, destroyed its meaning.
Huntard attempted to show that mutation and natural selection are different
And he did so in perfectly lucid English. Huntard is writing in his second language and yet he still gets his point across quite nicely. You are reading in your native language and you still don't seem to get it.
his sentence stated that natural selection produces 'inheritable traits'
Case in point. That isn't what he said.
My question, which you failed to answer, was what is the difference between these 'inheritable traits' and mutations?
The original statement was talking not about the traits themselves or how they originated, but the process by which they are filtered, i.e. natural selection.
If you want to know the distinction between an "inherited trait" and a mutation, Percy puts it well in Message 203, but really, there is little difference.
RM produces variation in inheritable traits.
NS filters those variations within a population, favouring traits that improve the survival/reproductive chances of the organisms within that population.
After over eighteen hundred posts on this board, have you really not grasped this?
Mutate and Survive

"A curious aspect of the theory of evolution is that everybody thinks he understands it." - Jacques Monod

This message is a reply to:
 Message 143 by Peg, posted 11-27-2009 1:33 AM Peg has not replied

Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 147 of 302 (537124)
11-27-2009 4:27 AM
Reply to: Message 140 by Peg
11-27-2009 12:18 AM


Re: Speciation
could this happen in human populations
Possibly, there are certainly many couples which have fertility problems so I would imagine the necessary genetic variability is there in the population. However I think that human population size is too large and gene flow between geographically distant populations too frequent for this to realistically happen except perhaps in the even to some cataclysmic environmental change producing some seriously long term isolation, and even then it would probably be a matter of chance if such incompatibilities became fixed.
has it happened?
No as far as I know. I don't know if there has been any specific research into inter-population fertility. Its another one of those things where ethics precludes doing the straightforward experiments we might in an animal model and instead we need to rely on whatever mating partners people happen to have chosen, we can't force a Maori to mate with an Inuit. Certainly it hasn't happened to the extent that there are clearly segregating breeding populations.
The possible exception is in the form of pre-mating isolation in behavioral rather than genetic terms since some insular ethnic groups prefer to keep marriages within their own populations. But this is a social rather than a biological barrier.
TTFN,
WK

This message is a reply to:
 Message 140 by Peg, posted 11-27-2009 12:18 AM Peg has replied

Replies to this message:
 Message 177 by Peg, posted 11-28-2009 12:30 AM Wounded King has not replied

Peg
Member (Idle past 4929 days)
Posts: 2703
From: melbourne, australia
Joined: 11-22-2008


Message 148 of 302 (537125)
11-27-2009 4:35 AM
Reply to: Message 145 by Huntard
11-27-2009 2:14 AM


Re: Here's mine
Huntard writes:
No it doesn't. It states that it makes those heritable traits more common, not that it produces them.
ok so this takes me back to my original question to you
What is the difference between mutations and inheritable traits?
You said that mutations are changes in dna. You also said that NS favors those inheritable traits.
So, are 'mutations' the same 'inheritable traits' you are refering to?
Edited by Peg, : No reason given.

This message is a reply to:
 Message 145 by Huntard, posted 11-27-2009 2:14 AM Huntard has replied

Replies to this message:
 Message 150 by Huntard, posted 11-27-2009 4:43 AM Peg has replied

Iblis
Member (Idle past 3895 days)
Posts: 663
Joined: 11-17-2005


Message 149 of 302 (537128)
11-27-2009 4:42 AM
Reply to: Message 139 by Peg
11-27-2009 12:16 AM


Re: Why?
ok, so If i have a baby which survives, thats natural selection taking place???
Yes. Keeping in mind that by survive, we don't just mean, lives long enough to be buried instead of being used as an ingredient in shampoo. We mean, lives long enough to have babies of her own. Got it?
Now, if you have a baby with one big eye in the middle of her forehead, that's mutation. This is true even if she becomes hair product. See the difference?
Good. So, if you have a baby born with one big eye in the middle of her forehead, who lives long enough to have babies of her own, some of whom either have, or have children who have, one big eye in the middle of their forehead, then that would be evolution.
But if you also have perfectly normal babies, and they have perfectly normal babies, that's still selection. And if they keep at it, generation after generation, and eventually the whole township looks a lot like you and no one at all looks like your ugly neighbors, that's still evolution.
And if a big polar bear comes along one day, and starts eating every one up, and is doing fine until he gets to your house, and the one-big-eye people come out, and it totally freaks him out and he runs away, then that's natural selection driven by mutation.
So if the one-big-eye people decide the non-bear-scaring regular descendants are inferior, and make a practice of not breeding with them, that's speciation. When occasionally some perverse couple do it anyway, that's hybridization. If mutations or other gene incompatibilies pile up to the point where the two groups stop being able to have babies together at all, even if they wanted to, that would be macro-evolution.
However, if it were just the blondes and brunettes who decided as a rule not to interbreed, that would still be speciation. And if, as a result of the excessive inbreeding involved in a practice like this, a hemophilia gene piled up on one side and a tendency toward lesions piled up on the other, so that whenever someone tried to break the rules and crossbreed, their embryos just immediately bled to death before they could even become placentique; that would still be macro-evolution.
Yeah, that does imply that at one time under some conditions blacks and whites could be considered separate species (falsely, as interbreeding did continue, the offspring were just assigned by fiat to one group rather than the other, but let it pass for this example) and that now, on the other hand, they couldn't. That would be an interesting example of genetic drift.
Note that at no point in this story does natural selection change anybody's traits. All it does is fail to kill some of them before they can spawn. The new traits come in the form of freaks and immigrants and inbreds. Natural selection doesn't care, it wants to kill them all. The freak immigrant inbreds might be the ones who dodge better, or the normal native mulattos. It doesn't care, it doesn't even know the difference, it just keeps spraying its house with different concoctions and complaining that nothing seems to quite take the vermin out completely.

This message is a reply to:
 Message 139 by Peg, posted 11-27-2009 12:16 AM Peg has replied

Replies to this message:
 Message 178 by Peg, posted 11-28-2009 12:42 AM Iblis has not replied

Huntard
Member (Idle past 2295 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 150 of 302 (537129)
11-27-2009 4:43 AM
Reply to: Message 148 by Peg
11-27-2009 4:35 AM


Re: Here's mine
Peg writes:
So, are 'mutations' the same 'inheritable traits' you are refering to?
No, the DNA is inheritable traits. Mutations are changes to those inheritable traits. When there are changes, NS starts to work on them, because the environment hasn't changed, but the traits of the individual have. Whether it is a positive or negative trait doesn't matter, NS will act upon it. It will also act when the environment changes, yet the traits remain the same.

I hunt for the truth
I am the one Orgasmatron, the outstretched grasping hand
My image is of agony, my servants rape the land
Obsequious and arrogant, clandestine and vain
Two thousand years of misery, of torture in my name
Hypocrisy made paramount, paranoia the law
My name is called religion, sadistic, sacred whore.
-Lyrics by Lemmy Kilmister of Motorhead

This message is a reply to:
 Message 148 by Peg, posted 11-27-2009 4:35 AM Peg has replied

Replies to this message:
 Message 151 by Peg, posted 11-27-2009 4:54 AM Huntard has replied

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