Definitions and species (hmmm...)

[siti]

I read about a scientist who saw little bits of something in water move without any movement by the water. So he figured it had to be motion in the little specks. When I come across it again, I'll let you know exactly who, what, and when.

Robert Brown, Brownian motion, 1827

When I took chemistry it was expected that we were to memorize the numbers and accept that without wondering out loud how in the world did they figure these things out. And I did, not bragging, but I WAS an honor/scholarship student. But it is interesting...to think about these things now.

I've said for years there's something badly wrong with our education system...no disrespect, but it is not unusual for us to produce award-winning students who understand nothing about the subject they won the prize for...and that's because we teach kids to remember stuff, not to understand it...and that's because education is "results-oriented"...if your pass rates fall as an educator you're in trouble. And as a student, we're not generally encouraged to ask questions - maybe that's changed/changing - I sure hope so...but I don't see it where I am now and it certainly wasn't like that 40-50 years ago when I was a student.

 

[YoursTrue]

"On the natural selection caused mutability of species and varieties" would be a more appropriate title given the material. But its less catchy I guess.

You really think natural selection cause(s) mutability?

Mutations are random

evolution.berkeley.edu

 

[YoursTrue]

Robert Brown, Brownian motion, 1827

I've said for years there's something badly wrong with our education system...no disrespect, but it is not unusual for us to produce award-winning students who understand nothing about the subject they won the prize for...and that's because we teach kids to remember stuff, not to understand it...and that's because education is "results-oriented"...if your pass rates fall as an educator you're in trouble. And as a student, we're not generally encouraged to ask questions - maybe that's changed/changing - I sure hope so...but I don't see it where I am now and it certainly wasn't like that 40-50 years ago when I was a student.

I see. So did you say that mutations are not random? not sure...

 

[YoursTrue]

Robert Brown, Brownian motion, 1827

I've said for years there's something badly wrong with our education system...no disrespect, but it is not unusual for us to produce award-winning students who understand nothing about the subject they won the prize for...and that's because we teach kids to remember stuff, not to understand it...and that's because education is "results-oriented"...if your pass rates fall as an educator you're in trouble. And as a student, we're not generally encouraged to ask questions - maybe that's changed/changing - I sure hope so...but I don't see it where I am now and it certainly wasn't like that 40-50 years ago when I was a student.

Thanks for reference to Robert Brown. Very interesting.
Ah, yes. August 1827: Robert Brown and Molecular Motion in a Pollen-filled Puddle

August 1827: Robert Brown and Molecular Motion in a Pollen-filled Puddle​

 

[sayak83]

So then the following is wrong, in your opinion?
Home → DNA and Mutations → Mutations are random

"Mutations are random​

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."

Mutations are random

evolution.berkeley.edu

Generally random but not necessarily.
A simple introduction to any subject only gives a sketch and omits the details. Like in physics, a simple high school intro of the atom will talk about electrons as a classical particle, omitting it's description as a quantum probability wave.

Anyways here are results that show that mutations are not really random.
Mutation bias reflects natural selection in Arabidopsis thaliana - Nature

 

[YoursTrue]

Robert Brown, Brownian motion, 1827

I've said for years there's something badly wrong with our education system...no disrespect, but it is not unusual for us to produce award-winning students who understand nothing about the subject they won the prize for...and that's because we teach kids to remember stuff, not to understand it...and that's because education is "results-oriented"...if your pass rates fall as an educator you're in trouble. And as a student, we're not generally encouraged to ask questions - maybe that's changed/changing - I sure hope so...but I don't see it where I am now and it certainly wasn't like that 40-50 years ago when I was a student.

P.S. I wasn't that interested in chemistry or physics back then. I just wanted to pass the course. I had no belief or lack of belief back then in God. I just didn't understand. But thanks anyway.

 

[sayak83]

You really think natural selection cause(s) mutability?

Mutations are random

evolution.berkeley.edu

Mutability means "change-ability".
Mutation is a specific technical term for change in DNA during reproduction and is not what I used in the hypothetical title. Darwin had no idea about genes.

 

[siti]

did you say that mutations are not random?

Nope...not me this time...genetic mutations are (more or less) random as far as I know. But the point is they are not "goal-oriented" - there is nothing to suggest that the (very long) sequence of genetic mutations that led to the development of the first legs (for example) was in any way "intended" to produce legs...but in an environment where the ability to escape a less mobile predator was "desirable", it would have certainly conferred a survival advantage and those mutations would have more readily propagated through the ensuing populations than the ones that didn't have that ability. So overall, the evolution of legs would not be entirely random because the natural environment is "selecting" in its favor, but the genetic mutations that gave rise to the possibility of legged organisms almost certainly was an entirely random sequence of DNA copying "errors". Of course Darwin had no idea about DNA - it was not discovered until 100 years later.

 

[YoursTrue]

Generally random but not necessarily.
A simple introduction to any subject only gives a sketch and omits the details. Like in physics, a simple high school intro of the atom will talk about electrons as a classical particle, omitting it's description as a quantum probability wave.

Anyways here are results that show that mutations are not really random.
Mutation bias reflects natural selection in Arabidopsis thaliana - Nature

The problem is that I think they are not really saying mutations are not random; but that the survival of a mutation and continued duplication of that mutation is dependent upon the situation. So I guess that you believe perhaps that the basic foundations of statements such as in the berkeley.edu website about mutations being random are now not true.(?)

 

[YoursTrue]

Mutability means "change-ability".
Mutation is a specific technical term for change in DNA during reproduction and is not what I used in the hypothetical title. Darwin had no idea about genes.

Mutability means change-ability? So?
What does this have to do with Darwin and his lack of knowledge of dna.
Oh, I might imagine that radiation might "cause" a mutation. Random or not. Outside influences might cause a mutation. So perhaps berkeley.edu might change its description of mutations being random.

 

[YoursTrue]

Nope...not me this time...genetic mutations are (more or less) random as far as I know. But the point is they are not "goal-oriented" - there is nothing to suggest that the (very long) sequence of genetic mutations that led to the development of the first legs (for example) was in any way "intended" to produce legs...but in an environment where the ability to escape a less mobile predator was "desirable", it would have certainly conferred a survival advantage and those mutations would have more readily propagated through the ensuing populations than the ones that didn't have that ability. So overall, the evolution of legs would not be entirely random because the natural environment is "selecting" in its favor, but the genetic mutations that gave rise to the possibility of legged organisms almost certainly was an entirely random sequence of DNA copying "errors". Of course Darwin had no idea about DNA - it was not discovered until 100 years later.

Now that you mention it, more or less random is interesting because -- mutations happen. P.S. so far as I know, most mutations are not beneficial that we see within the past few hundred years.

 

[YoursTrue]

I think that was because you were making the point that there is still not entirely general agreement among scientists on what exactly constitutes a "species". I don't think that matters at all in the face of the overall, overwhelming and undeniable evidence showing that the great variety of biological species (however many there are and however you define the term) that now exist are ultimately descended from a common biological ancestor many millions of years ago.

You can obfuscate and muddy the waters as much as you like by attempting to draw attention to differences of opinion among scientists about the definitions of words, but none of that will change the fact that all biology is related...and that this is even more plainly obvious now than it was to Darwin in the 1850s...

...so much so that anyone over the age of six would easily be able to understand the rudiments of evolution and observe for themselves that the fundamental concept - biological descent with modification - is, after all, as plain as the nose on their face - or at least the shape of that nose (etc) compared to that of their parents and siblings. The only thing that holds them back is what the 18th century English radical John Thelwall called "the chains of hereditary opinion" - what a shame that more than 200 years later those chains are still holding the minds of so many of our young captive.

That biology is related in living matter is not contested by me.

 

[siti]

Mutability means change-ability? So?

So - it can be used for the changeability of species - the sense in which Darwin used the term even in the first edition of Origin...

And...it can also mean the more specific - and definitely (at least mostly*) random imperfect copying of DNA in the reproductive cells of organisms.

*I say "mostly" and (earlier) "more or less" random because none of it takes place in a vacuum and even the copying of DNA is affected by environmental factors - though mostly this would be the environment of the cell in which the DNA was being copied - not whether it happened to be wet and windy outside that day...so its not entirely "random" in the strictest sense of the word, but it is certainly not "goal-oriented" - neither the parent organisms nor the cells, and much less the molecules of DNA themselves, have any idea whatsoever that they are "creating" something new and potentially evolutionarily significant...they are just doing what comes naturally.

 

[Pogo]

The problem is that I think they are not really saying mutations are not random; but that the survival of a mutation and continued duplication of that mutation is dependent upon the situation. So I guess that you believe perhaps that the basic foundations of statements such as in the berkeley.edu website about mutations being random are now not true.(?)

No, everybody is saying the same thing. at a basic level, mutations are random though there are cases where they are not quite random. What
berkeley and everybody else is saying is that the mutations which are selected by the environment is a non-random subset of all the random mutations and the selection is done by the environment in the form of increased reproductive success.
This is how useful traits come from a random source.

 

[sayak83]

Mutability means change-ability? So?
What does this have to do with Darwin and his lack of knowledge of dna.
Oh, I might imagine that radiation might "cause" a mutation. Random or not. Outside influences might cause a mutation. So perhaps berkeley.edu might change its description of mutations being random.

Random means equal probability for any DNA sites can change in a given cell replication event.
Non random means that this probability is not uniform but dependent on the DNA position within the strand.
The processes remain the same in both cases.

 

[Pogo]

Now that you mention it, more or less random is interesting because -- mutations happen. P.S. so far as I know, most mutations are not beneficial that we see within the past few hundred years.

Yup, if you have a deadly mutation you don't reproduce and that mutation is eliminated from the gene pool.

 

[Pogo]

At this level we can take mutations as random. If we move to a PhD level, we can discuss the exceptions.
The non-random part of evolution is how well the mutants/variations reproduce ie their success or fitness for their environment.

 

[siti]

most mutations are not beneficial

Correct. Most are neutral, a few are deleterious but non-lethal - some of these being "near-neutral" in the sense that whilst they are somewhat deleterious, they are not sufficiently harmful to be selected out - an even smaller proportion are actually lethal and do not get passed on anyway, and another handful per generation are actually beneficial.

 

[Subduction Zone]

You're almost making me laugh in a good way, kind of. I'm still trying to figure out how scientists figured out what constitutes an atom or molecule. I read about it, but -- there was only one explanation that started to make sense recently when I read about a scientist who saw little bits of something in water move without any movement by the water. So he figured it had to be motion in the little specks. When I come across it again, I'll let you know exactly who, what, and when. When I took chemistry it was expected that we were to memorize the numbers and accept that without wondering out loud how in the world did they figure these things out. And I did, not bragging, but I WAS an honor/scholarship student. But it is interesting...to think about these things now.

A good science class explains how they found out what they know now. And Einstein was one of the scientists that demonstrated the reality of atoms using Brownian motion. He "proved" that atoms were real. Something still up for debate at that time:

This Month in Physics History

Einstein and Brownian Motion

www.aps.org

Einstein probably deserved four Nobel Prizes in physics over his career.

 

[sayak83]

A good science class explains how they found out what they know now. And Einstein was one of the scientists that demonstrated the reality of atoms using Brownian motion. He "proved" that atoms were real. Something still up for debate at that time:

This Month in Physics History

Einstein and Brownian Motion

www.aps.org

Einstein probably deserved four Nobel Prizes in physics over his career.

Based on reading his biography it is clear that anti Semitic sentiments in Europe contributed a lot for him get only one and belated Nobel prize.