In What Way are Mutations Random?

[Thermos aquaticus]

There seems to be a lot of confusion about the concept of random mutations. I think it may be helpful to explain what scientists mean by random mutations, and to describe some of the experiments that illustrate how mutations are random.

So what do scientists mean when they say mutations are random? What they mean is mutations are random with respect to fitness. They do not mean that mutations are random with respect to a single base since some bases in a genome are more susceptible to mutation that others. Scientists do not mean that mutations are random with respect to rate since mutation rates can change over time and in response to the environment. What scientists mean by random mutations is that the mutations can be neutral, beneficial, or detrimental.

"Mutations can be beneficial, neutral, or harmful for the organism, but mutations do not "try" to supply what the organism "needs." Factors in the environment may influence the rate of mutation but are not generally thought to influence the direction of mutation. For example, exposure to harmful chemicals may increase the mutation rate, but will not cause more mutations that make the organism resistant to those chemicals."
Mutations are random

In other words, the mechanisms that produce mutations do not know which mutations will help or hurt the organism. The mechanisms that produce mutations are blind to the needs of the organism.

To help illustrate this fact we can look to an experiment first done by Joshua and Esther Lederberg back in the 1950's. The technique they used is called replica plating, and it is used to show that a beneficial mutation conferring phage resistance occurs in an environment devoid of phage. That is, the mutation occurs when it isn't beneficial meaning that the processes that produce this mutation have no idea if it will be beneficial in the given environment.

The first step in using this technique is to start with a single bacterium that is sensitive to phage. That single bacterium multiplies until there are billions of bacterium, and those bacterium are poured onto a plate (the master plate seen below). You let those billions of bacteria multiply some more until the form a lawn of bacteria, all of which share a single common ancestor that was phage sensitive. You then use a felt stamp to transfer the lawn of bacteria to new plates that have phage on them, just like using a rubber stamp to move ink from the pad onto a piece of paper. Since the new plates have phage already on them a lot of those bacteria will be killed by the phage. However, you will find that a few colonies will grow on each plate. These are phage resistant colonies.

The most interesting part of this experiment is that the pattern of phage resistant colonies is the same on each plate. Why is that? The answer is that phage resistance is due to a mutation that occurred in one of the bacteria on the master plate. It is also important to note that there was no phage on the master plate. The mutation that confers phage resistance occurred in the absence of phage.

This is what scientists mean by random mutations. There is no meaningful connection between what the organism needs and the mutations that occur. Each are blind to the other.

 

[David T]

There seems to be a lot of confusion about the concept of random mutations. I think it may be helpful to explain what scientists mean by random mutations, and to describe some of the experiments that illustrate how mutations are random.

So what do scientists mean when they say mutations are random? What they mean is mutations are random with respect to fitness. They do not mean that mutations are random with respect to a single base since some bases in a genome are more susceptible to mutation that others. Scientists do not mean that mutations are random with respect to rate since mutation rates can change over time and in response to the environment. What scientists mean by random mutations is that the mutations can be neutral, beneficial, or detrimental.

"Mutations can be beneficial, neutral, or harmful for the organism, but mutations do not "try" to supply what the organism "needs." Factors in the environment may influence the rate of mutation but are not generally thought to influence the direction of mutation. For example, exposure to harmful chemicals may increase the mutation rate, but will not cause more mutations that make the organism resistant to those chemicals."
Mutations are random

In other words, the mechanisms that produce mutations do not know which mutations will help or hurt the organism. The mechanisms that produce mutations are blind to the needs of the organism.

To help illustrate this fact we can look to an experiment first done by Joshua and Esther Lederberg back in the 1950's. The technique they used is called replica plating, and it is used to show that a beneficial mutation conferring phage resistance occurs in an environment devoid of phage. That is, the mutation occurs when it isn't beneficial meaning that the processes that produce this mutation have no idea if it will be beneficial in the given environment.

The first step in using this technique is to start with a single bacterium that is sensitive to phage. That single bacterium multiplies until there are billions of bacterium, and those bacterium are poured onto a plate (the master plate seen below). You let those billions of bacteria multiply some more until the form a lawn of bacteria, all of which share a single common ancestor that was phage sensitive. You then use a felt stamp to transfer the lawn of bacteria to new plates that have phage on them, just like using a rubber stamp to move ink from the pad onto a piece of paper. Since the new plates have phage already on them a lot of those bacteria will be killed by the phage. However, you will find that a few colonies will grow on each plate. These are phage resistant colonies.

The most interesting part of this experiment is that the pattern of phage resistant colonies is the same on each plate. Why is that? The answer is that phage resistance is due to a mutation that occurred in one of the bacteria on the master plate. It is also important to note that there was no phage on the master plate. The mutation that confers phage resistance occurred in the absence of phage.

This is what scientists mean by random mutations. There is no meaningful connection between what the organism needs and the mutations that occur. Each are blind to the other.

In religion randomness is described in story. This story has fitness, it fits how we think. This story is pure random has zero relationship to reality at all!!! There can be no real not real random like religion we need real Random then it's real like science.

 

[Daemon Sophic]

In religion randomness is described in story. This story has fitness, it fits how we think. This story is pure random has zero relationship to reality at all!!! There can be no real not real random like religion we need real Random then it's real like science. View attachment 21245

Huh?

 

[Thermos aquaticus]

In religion randomness is described in story. This story has fitness, it fits how we think. This story is pure random has zero relationship to reality at all!!! There can be no real not real random like religion we need real Random then it's real like science.

If you are going to comment in this thread please try to stay on topic.

 

[ScottySatan]

Mutations are not random. Scientists say that mutations are not random. High school science teachers, journalists, and evolution arguers are the only ones who say that mutations are random.

 

[Guy Threepwood]

There seems to be a lot of confusion about the concept of random mutations. I think it may be helpful to explain what scientists mean by random mutations, and to describe some of the experiments that illustrate how mutations are random.

So what do scientists mean when they say mutations are random? What they mean is mutations are random with respect to fitness. They do not mean that mutations are random with respect to a single base since some bases in a genome are more susceptible to mutation that others. Scientists do not mean that mutations are random with respect to rate since mutation rates can change over time and in response to the environment. What scientists mean by random mutations is that the mutations can be neutral, beneficial, or detrimental.

"Mutations can be beneficial, neutral, or harmful for the organism, but mutations do not "try" to supply what the organism "needs." Factors in the environment may influence the rate of mutation but are not generally thought to influence the direction of mutation. For example, exposure to harmful chemicals may increase the mutation rate, but will not cause more mutations that make the organism resistant to those chemicals."
Mutations are random

In other words, the mechanisms that produce mutations do not know which mutations will help or hurt the organism. The mechanisms that produce mutations are blind to the needs of the organism.

To help illustrate this fact we can look to an experiment first done by Joshua and Esther Lederberg back in the 1950's. The technique they used is called replica plating, and it is used to show that a beneficial mutation conferring phage resistance occurs in an environment devoid of phage. That is, the mutation occurs when it isn't beneficial meaning that the processes that produce this mutation have no idea if it will be beneficial in the given environment.

The first step in using this technique is to start with a single bacterium that is sensitive to phage. That single bacterium multiplies until there are billions of bacterium, and those bacterium are poured onto a plate (the master plate seen below). You let those billions of bacteria multiply some more until the form a lawn of bacteria, all of which share a single common ancestor that was phage sensitive. You then use a felt stamp to transfer the lawn of bacteria to new plates that have phage on them, just like using a rubber stamp to move ink from the pad onto a piece of paper. Since the new plates have phage already on them a lot of those bacteria will be killed by the phage. However, you will find that a few colonies will grow on each plate. These are phage resistant colonies.

The most interesting part of this experiment is that the pattern of phage resistant colonies is the same on each plate. Why is that? The answer is that phage resistance is due to a mutation that occurred in one of the bacteria on the master plate. It is also important to note that there was no phage on the master plate. The mutation that confers phage resistance occurred in the absence of phage.

This is what scientists mean by random mutations. There is no meaningful connection between what the organism needs and the mutations that occur. Each are blind to the other.

and what did the bacteria 'evolve' into?

 

[Thermos aquaticus]

Mutations are not random. Scientists say that mutations are not random.

That claim is begging for a reference.

The papers I have read state quite clearly that mutations are random with respect to fitness. In fact, Salvador Luria won a Nobel prize in part because of his work demonstrating the random nature of mutation. You can read the classic Luria and Delbruck paper for yourself:

MUTATIONS OF BACTERIA FROM VIRUS SENSITIVITY TO VIRUS RESISTANCE

The Lederbergs also demonstrated the nature of random mutations in their seminal work:

REPLICA PLATING AND INDIRECT SELECTION OF BACTERIAL MUTANTS

 

[Thermos aquaticus]

and what did the bacteria 'evolve' into?

They evolved into strains that were resistant to antibiotics and bacteriophage.

 

[Guy Threepwood]

They evolved into strains that were resistant to antibiotics and bacteriophage.

so the bacteria evolved into more bacteria,

Do you think that if all bacteria were restricted from adapting their resistance, that would be a viable design?

 

[Thermos aquaticus]

so the bacteria evolved into more bacteria,

Just as we should observe if evolution is true.

Do you think that if all bacteria were restricted from adapting their resistance, that would be a viable design?

What does this have to do with the observation that mutations are random with respect to fitness? The bacteria did not create these mutations in response to antibiotics and bacteriophage which is why mutations are said to be random.

 

[Guy Threepwood]

Just as we should observe if evolution is true

and if it is not!.

What does this have to do with the observation that mutations are random with respect to fitness? The bacteria did not create these mutations in response to antibiotics and bacteriophage which is why mutations are said to be random.

The contention is that macro morphological evolution occurs through such random changes, this ain't an example of that. Many good product designs involve a random element to provide variety within the design, they don't spontaneously create new designs this way, and neither do bacteria

 

[Thermos aquaticus]

and if it is not!.

The common ancestor of humans and chimps was a primate. We are still primates.

The common ancestor of humans and bears was a mammal. We are still mammals.

The common ancestor of humans and trout was a vertebrate. We are still vertebrates.

See a pattern? You don't evolve out of your ancestry.

The contention is that macro morphological evolution occurs through such random changes, this ain't an example of that.

I am merely showing what scientists mean when they say that mutations are random, and also citing the experiments that led them to the conclusion that mutations are random.

Many good product designs involve a random element to provide variety within the design, they don't spontaneously create new designs this way, and neither do bacteria

Any evidence to back these claims?

 

[ScottySatan]

Sorry to barge in again, but scientists don't say that mutations are random, because they aren't. A scientist might casually say by mistake that they're random, but if you question them about it, they will correct themselves.

DNA is wound up by optically dense heterochromatin and wound around histones, right? Long repeats will basepair incorrectly during replication. There are recombination jungles and deserts.

However, this doesn't work against evolutionary theory, it actually strengthens it because random SNPs are too slow to account for the observed rate of change.

 

[Thermos aquaticus]

Sorry to barge in again, but scientists don't say that mutations are random, because they aren't.

What observations demonstrate that mutations are not random with respect to fitness?

However, this doesn't work against evolutionary theory, it actually strengthens it because random SNPs are too slow to account for the observed rate of change.

Reference?

 

[Etritonakin]

While some specific mutations may be random, the overall effect of DNA-based evolution as a whole has been toward not only fitness to survive, but mastery of environment -and now even mastery of self within environment -mastery being the ultimate fitness to survive.
Specific mechanisms involved may themselves be blind, the entire process has certainly "seen" and reacted to produce the outcome.
That is not to say the process itself understands and considers what it sees in a complex way, however.


Just had a random thought about this....
"The most interesting part of this experiment is that the pattern of phage resistant colonies is the same on each plate. Why is that? The answer is that phage resistance is due to a mutation that occurred in one of the bacteria on the master plate. It is also important to note that there was no phage on the master plate. The mutation that confers phage resistance occurred in the absence of phage."

I have heard that some believe radiation drives mutation -radiation being external.
Is it (I realize this is "out there" -and I am mostly ignorant about this particular subject) possible that something not yet considered (some quantum freakiness or something) causes the same resistance mutation where phage is physically absent by signalling it to the other nearby bacteria somehow -on a different level? The bacteria are separated physically to the satisfaction of the experimenter -but are they truly separated in regard to how a mutation might be caused?

 

[Thermos aquaticus]

While some specific mutations may be random, . . .

All of the mutations science has looked at have been random.

the overall effect of DNA-based evolution as a whole has been toward not only fitness to survive, but mastery of environment -and now even mastery of self within environment -mastery being the ultimate fitness to survive.

That's because evolution includes natural selection which selects for random mutations that increase fitness.

I have heard that some believe radiation drives mutation -radiation being external.
Is it (I realize this is "out there" -and I am mostly ignorant about this particular subject) possible that something not yet considered (some quantum freakiness or something) causes the same resistance mutation where phage is physically absent by signalling it to the other nearby bacteria somehow -on a different level? The bacteria are separated physically to the satisfaction of the experimenter -but are they truly separated in regard to how a mutation might be caused?

Radiation is one of many possible causes, but probably the most common cause is just the chemistry of biology itself. The mutations that occur are usually a switch between DNA bases that are similar to each other, which are called transitions. IOW, It is the physical similarity between bases that drives most of the mutations. There is no known process by which an organism can sense an environmental threat or opportunity and then mutate a specific base in their genome or any other organism's genome.

Here is a picture of the 4 DNA bases:



Adenosine and guanine are similar in size and both have two rings. Thymine and cytosine are also similar in size and have a single ring. It is their physical similarities that cause the wrong base to sometimes be inserted. Dissimilar bases are also traded out for one another, but at a lower rate.

 

[Etritonakin]

All of the mutations science has looked at have been random.



That's because evolution includes natural selection which selects for random mutations that increase fitness.



Radiation is one of many possible causes, but probably the most common cause is just the chemistry of biology itself. The mutations that occur are usually a switch between DNA bases that are similar to each other, which are called transitions. IOW, It is the physical similarity between bases that drives most of the mutations. There is no known process by which an organism can sense an environmental threat or opportunity and then mutate a specific base in their genome or any other organism's genome.

Here is a picture of the 4 DNA bases:



Adenosine and guanine are similar in size and both have two rings. Thymine and cytosine are also similar in size and have a single ring. It is their physical similarities that cause the wrong base to sometimes be inserted. Dissimilar bases are also traded out for one another, but at a lower rate.

I have heard differently (that natural selection is only one aspect -and others are more input-output than purely coincidental), but am not prepared for a discussion myself -wish I had time to study it.

 

[Thief]

if I were God....and got tired of the random collection of dinosaurs I've created.....
I might drop a random meteor into the petri (biosphere) dish

and then pick at random a nice specimen of Man
place him to ideal living conditions
manipulate his mind
take a sample of his flesh as he sleeps
clone the sample to full staure
genetically alter the sample as it develops into a female

test the alterations made

release the specimens into the environment

and wait see what randomly happens

 

[Thermos aquaticus]

I have heard differently (that natural selection is only one aspect -and others are more input-output than purely coincidental), but am not prepared for a discussion myself -wish I had time to study it.

Feel free to ask any questions. If nothing else, I could at least help you understand why scientists have concluded that mutations are random with respect to fitness.

 

[Etritonakin]

Feel free to ask any questions. If nothing else, I could at least help you understand why scientists have concluded that mutations are random with respect to fitness.

Just too big a subject for me right now -and too many levels. Sort of an... I understand computers, but not programming kind of thing.