Philosophy Discussion Forums | A Humans-Only Club for Open-Minded Discussion & Debate

[Bobsmith76]

What evidence is there for natural selection on the molecular level? In answering this question people routinely make four major mistakes, one, they assume that natural selection is the same as common ancestry. They're not. Common ancestry and Natural Selection acting on random mutation are two very different theories and are not related. Evidence for common ancestry is not evidence for Natural Selection. Two, they believe that a philosophical argument counts as scientific evidence. For example if I say that the well-adapted survive and therefore are more likely to pass on their genes, this is not rigorous, empirical evidence for NS acting on random mutation, this is mere philosophical speculation of why nature MIGHT account for the diversity of species. It is not hard, rigorous, scientific evidence. I've been down this road before and since there is no hard evidence for NS the Darwinists always use mere philosophical arguments to justify their stance because that is all they have. The third mistake they make is providing evidence that the strong survive such as peppered moths. The fact white moths died off during decades of high pollution then made a come back when the smog was dispelled is evidence that if you're well-adapted to your enivornment, you're more likely to survive, or the strong survive. I agree that the strong survive. How could I not? What could be more common-sensical? I do not agree that

1. the strong survive
2. therefore, natural selection can build an organ

or even worse:

1. natural selection destroys
2. therefore it can build

or

1. a new gene appears
2. therefore Natural Selection caused it to appear

The above three are fallacies.

Fourthly, to my surprise, many Darwinists claim that NS does not build. The only way you can cause an organ to appear is to build it. Even if that building takes a millions of years, over many generations, then it is still building.

[Mark]

Nature is not perfect. Weak organisms are being born. Why is that, if only strong survive?

[Bobsmith76]

I specifically wrote in my OP that I am not asking for logical, philosophical reasons for why NS is true but hard empirical evidence.

However, even from your reply it looks as thought you're arguing that NS does not account for all the diversity of life.

[PhilosophiliacEdward]

What evidence is there for natural selection on the molecular level?

As far as I know, there are no theories on natural selection on the molecular level, because molecules are just a combination of atoms.

If you mean to ask what evidence there is for natural selection in general, then the evidence comes from fossil records and the variation of members from the same species is evidence.

1. the strong survive
2. therefore, natural selection can build an organ

or even worse:

1. natural selection destroys
2. therefore it can build

or

1. a new gene appears
2. therefore Natural Selection caused it to appear

The above three are fallacies.

Correct, the above three arguments are fallacies. Furthermore, none of those are part of the theory of natural selection.

It seems to me that you are mistaking fitting a theory to evidence (which is proper science) and fitting evidence to a theory.

The theory of natural selection is a theory meant to explain the fossil record and the variations of species. But from the arguments you showed, it seems as if you are taking the theory (which is just an explanation) and ignoring the reason for the theory (the fossil records and variation of species).

[Bobsmith76]

As far as I know, there are no theories on natural selection on the molecular level, because molecules are just a combination of atoms.

I mean DNA evidence, which most people call evidence on the molecular level. DNA is technically one huge molecule.

If you mean to ask what evidence there is for natural selection in general, then the evidence comes from fossil records and the variation of members from the same species is evidence.

Fossils are evidence of an affect, they are not evidence of the cause. Species change, that's a fact. What's the cause? NS has been put forward as an explanation but there is extremely little evidence for it.

you are taking the theory (which is just an explanation) and ignoring the reason for the theory (the fossil records and variation of species).

You're using circular reasoning. What you're saying is:

Variation of species is evidence for why there is variation of species


EDIT: I'm going to leave this thread. I've been debating it elsewhere on the web. I've got some work that I need to catch up on. So if you respond, do not expect a response.

[PhilosophiliacEdward]

you are taking the theory (which is just an explanation) and ignoring the reason for the theory (the fossil records and variation of species).

You're using circular reasoning. What you're saying is:

Variation of species is evidence for why there is variation of species


EDIT: I'm going to leave this thread. I've been debating it elsewhere on the web. I've got some work that I need to catch up on. So if you respond, do not expect a response.

Although there is little reason to respond, I'd just like to point out that it is not circular reasoning. What I was saying was that the theory of Natural Selection is an explanation for the fact that there is variation of species.

[Antone]

What evidence is there for natural selection on the molecular level?

First, I do NOT believe in Darwinian-like notions of evolution.
Second, I think you may be using this term in an atypical way, to indicate one species changing into another. This is not what it normally implies. Rather it is used to indicated minor changes within a species, which I believe is called "molecular drift".

The evidence for molecular drift is actually quite strong. And if you think about it, you'll probably realize that you are already aware of some of them. For instance, you probably realize that when you go to the doctors for a sore throat, they tell you to finish all of your medicine because the bacteria that causes strepthroat can become harder to kill if you don't. In other words, molecular drift occurs. If the bacteria aren't completely killed off, those bacteria most able to survive the medication reproduce and the next time they are harder to kill.

Many other examples occur. For instance, over time, scientists have observed changes in coral reefs or algae--and so forth.

Although it isn't driven by natural selection, we also have different breeds of cats and dogs, and so forth. While this doesn't demonstrate that such genetic separation can happen NATURALLY it does demonstrate that it can happen.

The problem with genetic drift, of course, is that there isn't any evidence (that I know of) which conclusively demonstrates that it can span the bridge from one species to another. When released into the wild, very different breeds of dogs will interbreed and very quickly "revert" to a stereotypical mut kind of dog.

Similarly, "super-bacteria" that exist in an environment without drugs tend to drift back towards being "normal" bacteria.

This is why those who reject Darwinian Evolution tend to make a clear distinction between MICRO and MACRO evolution. Microevolution is molecular drift--and it has been firmly established that this happens. Macroevolution, by contrast is one species changing into another, and I do not believe that any conclusive evidence of this exists.

A fair amount of circumstantial evidence exists: such as the fossil record. But I believe that every instance of [this sort of evidence] faces serious difficulties within the Darwinian model. In other words, there is no evidence that one-way changes in species because of natural selection. Darwin certainly did not provide any examples in his "Origin of Species".

In addition, several cases have been exaggerated and misinterpreted to imply more than is justified by the actual evidence. A good example of this is the history of the Peppered Moth. Peppered Moths range from [light with dark spots] to [dark with light spots]. Before the Industrial Revolution, the majority of Peppered Moths were the lighter varieties. Presumably, his allowed them to hide easily on the light colored trees. But as pollution darkened the trees, the majority of Peppered Moths became the dark colored ones.

Bernard Kettlewell did an experiment that seemed to confirm that the light colored moths were easier for birds to spot (and thus eat) on the dark colored trees--and this was hailed as 'evidence' of natural selection in process. But there are a number of difficulties with this premise. I will only discuss one--which is that after pollution laws were passed (and the trees lightened in color again) the light colored moths once again became a larger proportion of the population.

What is significant about this fact is that it can be seen as an example that 'disproves' macroevolution. The survivability of the species is improved if it has variation, because when the conditions change, the species can change. Changing to another species basically means that this change can't be reversed--but this would reduce the survivability of the species, for if the moths couldn't change back to light colored when the trees turned light again, they presumably would have more trouble surviving.

... many Darwinists claim that NS does not build.

I agree with the basics of what you're saying, but I'm not sure I agree with the way you're saying it.

Darwinian modeled his evolutionary theory after an Economic theory of that time. I believe it basically said that the tougher the economic environment, the more capable the entrepreneurs have to be to survive in that environment. This is basically the same dynamics that evolution suggests... with the twist being that mutations among animals can occur (and accumulate) because those mutations that give the animal a favorable advantage will be irreversibly preserved in future generations.

The evidence, however, suggests that such 'mutations' are rarely (if ever) beneficial. And even if this weren't the case, there is no empirical evidence that such mutations can lead to irreversible change. Such a change would actually make the organism weaker in terms of long-term survivability, because it would no longer be able to change back to what it was when conditions go back to what they were.

[Admiral usher]

What evidence is there for natural selection on the molecular level?

First, I do NOT believe in Darwinian-like notions of evolution.
Second, I think you may be using this term in an atypical way, to indicate one species changing into another. This is not what it normally implies. Rather it is used to indicated minor changes within a species, which I believe is called "molecular drift".

The evidence for molecular drift is actually quite strong. And if you think about it, you'll probably realize that you are already aware of some of them. For instance, you probably realize that when you go to the doctors for a sore throat, they tell you to finish all of your medicine because the bacteria that causes strepthroat can become harder to kill if you don't. In other words, molecular drift occurs. If the bacteria aren't completely killed off, those bacteria most able to survive the medication reproduce and the next time they are harder to kill.

Many other examples occur. For instance, over time, scientists have observed changes in coral reefs or algae--and so forth.

Although it isn't driven by natural selection, we also have different breeds of cats and dogs, and so forth. While this doesn't demonstrate that such genetic separation can happen NATURALLY it does demonstrate that it can happen.

The problem with genetic drift, of course, is that there isn't any evidence (that I know of) which conclusively demonstrates that it can span the bridge from one species to another. When released into the wild, very different breeds of dogs will interbreed and very quickly "revert" to a stereotypical mut kind of dog.

Similarly, "super-bacteria" that exist in an environment without drugs tend to drift back towards being "normal" bacteria.

This is why those who reject Darwinian Evolution tend to make a clear distinction between MICRO and MACRO evolution. Microevolution is molecular drift--and it has been firmly established that this happens. Macroevolution, by contrast is one species changing into another, and I do not believe that any conclusive evidence of this exists.

A fair amount of circumstantial evidence exists: such as the fossil record. But I believe that every instance of [this sort of evidence] faces serious difficulties within the Darwinian model. In other words, there is no evidence that one-way changes in species because of natural selection. Darwin certainly did not provide any examples in his "Origin of Species".

In addition, several cases have been exaggerated and misinterpreted to imply more than is justified by the actual evidence. A good example of this is the history of the Peppered Moth. Peppered Moths range from [light with dark spots] to [dark with light spots]. Before the Industrial Revolution, the majority of Peppered Moths were the lighter varieties. Presumably, his allowed them to hide easily on the light colored trees. But as pollution darkened the trees, the majority of Peppered Moths became the dark colored ones.

Bernard Kettlewell did an experiment that seemed to confirm that the light colored moths were easier for birds to spot (and thus eat) on the dark colored trees--and this was hailed as 'evidence' of natural selection in process. But there are a number of difficulties with this premise. I will only discuss one--which is that after pollution laws were passed (and the trees lightened in color again) the light colored moths once again became a larger proportion of the population.

What is significant about this fact is that it can be seen as an example that 'disproves' macroevolution. The survivability of the species is improved if it has variation, because when the conditions change, the species can change. Changing to another species basically means that this change can't be reversed--but this would reduce the survivability of the species, for if the moths couldn't change back to light colored when the trees turned light again, they presumably would have more trouble surviving.

... many Darwinists claim that NS does not build.

I agree with the basics of what you're saying, but I'm not sure I agree with the way you're saying it.

Darwinian modeled his evolutionary theory after an Economic theory of that time. I believe it basically said that the tougher the economic environment, the more capable the entrepreneurs have to be to survive in that environment. This is basically the same dynamics that evolution suggests... with the twist being that mutations among animals can occur (and accumulate) because those mutations that give the animal a favorable advantage will be irreversibly preserved in future generations.

The evidence, however, suggests that such 'mutations' are rarely (if ever) beneficial. And even if this weren't the case, there is no empirical evidence that such mutations can lead to irreversible change. Such a change would actually make the organism weaker in terms of long-term survivability, because it would no longer be able to change back to what it was when conditions go back to what they were.[/quote

I don't understand how evolution works but I have a notion of my own.Perhaps someone can explain why I am wrong.

Lets say species x who is susceptical to damage from lets say heat.The climate changes and gets hotter.The species begins to die off.Now among the species there is some difference.An example of this might be genes of a particular group say humans are negative because they contain say a gene causing an inherited trait.We usually think of diseases such as cancer,or postive examples such as tallness shortness and a myriad of differences.

Now those creatures who have a certain difference than others of the same kind namely the heat gene prevents them from dying off. of course this all takes a long time. So what we now have is a creature which is slightly different.Then again it continues to change according to the conditions of the world.After a few million years we have a species that looks and behaves quite differently

But the creatures,plants,species or what ever you want to call them are still related to each other.Science uses evidence for proof that this is true.

I don't think there is any reason for this particular way that life works.It just does.
Wouldn't be nice if we could speed up the evolutionary process (if there is one) and put a few hundred million years into a time sequence of years,months weeks and hours.
Lets make our expirement.We are advanced enough to see every gene and all other parts that may be included in the possible evolutionary theory. Something like they do now with time lapse cameras to capture the motion of plants.
Yes why not.At my age 78 I won't see this but you younguns
will live to see many marvels.

I would say that evolution is an accident. Now as far as the grey moths are concerned I don't think that this is a case of evolution but gives a fairly good idea about how it might work.

I am not a scientist so what ever I have written is just an idea of what evolution might be like.Please tell me about my idea of evolution.
thanks a lot Admiral Usher

[Antone]

I don't understand how evolution works but I have a notion of my own.
...Lets say species x is susceptible to damage from heat. The climate gets hotter; the species begins to die off. Now among the species there are creatures with differences, namely a heat gene that prevents them from dying off. Of course this all takes a long time. So what we now have is a creature which is slightly different.

Okay, I was with you up until that last line. Why would what we have after a long time be inherently different?

Presumably, before the changes that brought increased heat, there were individuals that had the heat gene that gives them increased tolerance, otherwise they would not have been around to survive. These individuals pass this gene on to a certain percentage of their children. As the heat becomes more and more of a problem, those individuals with this gene have an advantage that allows them to survive in greater numbers--so more of this gene will tend to be passed on, but there will continue to be those without the gene in the mix. It seems to me, since the gene is obviously a recessive gene (else there would be a lot of these types to begin with) if the heat ever goes away, so will the preponderance of the gene in the gene pool.

If the heat becomes so intense that those without the gene cannot survive at all, then most of the children will die. Keep in mind that the people will travel to a more favorable climate, or change their customs to ease the difficulties with the heat before simply allowing the majority of their members to die off. So for the conditions to be so horrible that those without the gene die; so will most of the children with the gene. The gene isn't a magic pill, its a slightly favorable survivability trend. Those with it won't need quite as much water, perhaps. They'll remain stronger and healthier. But if it's bad enough to kill all of the ones without the gene, those with it will be in very bad shape as well.

If we assume that this does happen, then presumably the gene could be breed out so that only heat tolerant individuals remain. Presumably, however, the heat tolerant ones might be less favorably conditioned to the cold. So if the environment ever turns cold again, they will be at a severe disadvantage, because they won't have any individuals with a higher tolerance to the cold.

This is why, generally speaking, nature is resistant to creating a system whereby all the individuals with a specific type of gene can be breed out of the population. It would likely do more harm to long-term survivability than it did good.

Because of this, the outer appearance of the population may change--but the inner potential for tolerance to the cold would most likely remain in virtually any population that survived the heat change without it being a near extinction event for that population.

This situation does not seem to promote evolutionary change of a non-cataclysmic nature.

Wouldn't be nice if we could speed up the evolutionary process (if there is one) and put a few hundred million years into a time sequence of years,months weeks and hours.

Actually, in a sense, we can do this... breeders perform artificial selection all the time. Animals have two tendencies. 1) is that they pay no attention to certain differences in characteristics. So a little toy poodle will sniff around a Great Dane and if they get a chance they'll copulate. When they do the dog that results will look like neither type of dog. But breeders can select for specific characteristics doing in a relatively few generations what would be impossible to do over may eons of natural breeding. 2) Other animals have a tendency to avoid animals that are different. So an albino wolf (or even one that has fur that is darker than the rest of the pack)will be generally be avoided by other wolves. Again, this tends to limit the likelihood that other "uncharacteristic" wolves will be born. And again, artificial selection can breed these animals, when nature would not. Thus, we have a wide range of races in domestic animals such as dogs and cats. Similarly, hawks have been breed for certain characteristics for several thousands of years, and so forth.

Yet, over all of these many centuries of artificial breeding, there has never been a new species of animals that has been breed out of their dogness or catness or hawkness.

Furthermore, while dog races come in a wide range of sizes and shapes, there seems to be distinct limit, beyond which these animals cannot go any further. Hawks have been breed for size and speed for centuries--but they are no bigger now than they were many centuries ago. And if the larger hawks are released into the wild, their offspring quickly revert to the smaller sizes.

The characteristics of a species are a bit like a rubber band. We can stretch the boundaries and twist the rubber band into odd shapes, but we can't go beyond what the rubber band can endure or it will break. And if we release the pressure on the rubber band, it will return to its original shape.

In my opinion, this elasticity of the species is designed to allow it to survive changes in the environment that make having one shape an advantage over another--not to transform the species into something other than what it is.

...as far as the peppered moths are concerned I don't think that this is a case of evolution but gives a fairly good idea about how it might work.

Not really. If you look closely at the actual case, it is an example of how "evolutionary proof" is often deeply flawed. It does not demonstrate evolution--it demonstrates the elastic stability that I've been talking about.

In this case, there was no actual change in the moths at all. Presumably, the percentage of dark moths increased for a time (during times of higher pollution concentration), but when pollution decreased in later years the percentage of dark moths declined again. And even here the data is flawed, since the records actually show many inconsistencies--for example, in many cases the population percentages changed before the discoloration on the trees. And in some areas the trend was actually the reverse--pollution causing increases in the lighter moths--both suggest that it wasn't the discoloration of the trees that caused the changes in the moth populations. And so we cannot assume that it is evidence of evolution.