Definition of evolution and the distinction between micro/macro


(Chris) #202

I guess that’s why you included those things in your definitions of evolution, microevolution, and macroevolution.


(Chris) #203

The evidence already given.


(Chris) #204

I guess that’s why you included those things in your definitions.


(Haywood Clark) #205

I haven’t seen that you’ve cited any evidence, Chris. You’re claiming that the evidence shows something, and I’m simply asking you to point me to the actual evidence itself.

T. aquaticus has offered actual evidence that very clearly contradicts your claim about what the evidence shows.

As a basis for discussion, could you start by objectively defining what you call the “Chloroquine Resistance Mutation Cluster”?


(George Brooks) #206

@aarceng,

I find YOUR definition to be idiosyncratic and a one of a kind description that nobody will know how to correctly apply.


(Lynn Munter) #207

I can see this conversation has run its course. Thanks for the discourse on a valuable subject.

My definitions, if you’re curious, would run something like this:

Microevolution: a relatively small number of changes in allele frequency. (This can include gains or losses in information*, functions or features.)

Macroevolution: a relatively large number of changes in allele frequency. (This can include gains or losses in information*, functions or features.)

*Assuming everyone can agree on what exactly information is in this context (probably not).


(Chris) #208

@Lynn_Munter. Do you have a definition for [the theory of] Evolution? Feel free to qualify what flavour your definition is for, just like I did. ( e.g. Evolution (the Neo-Darwinian Theory of) )


(Chris) #209

And I find YOUR definitions to be … well actually I can’t FIND your definitions.


(George Brooks) #210

@aarceng

My definition is the same as @Lynn_Munter’s:


(Chris) #211

Does that include her definition of Evolution which she hasn’t posted yet?


(Haywood Clark) #212

Once you’ve covered macro and micro, what’s left?


(Lynn Munter) #213

It’s upthread, post 26:

(Note: the word ‘gauntlets’ could be changed to another word like ‘pressures,’ even though it’s more boring that way.)

You then responded in post 66 and I responded again in post 70, including a somewhat facetious variation on your definition, pointing out that the main mechanism of descent is just reproduction (what you are looking for is more like the mechanism leading to modern diversity):

And then in post 193 you repeated your original definition as though no discussion at all had occurred, at least none worth modifying it for, which prompted me to reply:

I suppose one last note is in order:

It’s not the biology textbook definition, but I suppose it’s okay for a common understanding of the theory of evolution as used in discussions like this one.


(George Brooks) #214

@aarceng

I provided a link to this very posting already… all you had to do was click on it.

SO … here’s the exact quote… you don’t have to click on anything.

2 definitions of evolution from a scientific viewpoint (more or less)… I am not personally a big fan of distinguishing between Micro and Macro… but sometimes it helps the Creationists to use the terms…


(Lynn Munter) #215

@gbrooks9, I’m sure @aarceng was aware of that post. He was objecting that he had given three definitions and I appeared to have given only two, because I guess he didn’t remember me from over a hundred posts ago. I shouldn’t have assumed he would! It was just a bit of bother to track down those early quotes so it took me a little while. :woman_technologist:


(Chris) #216

Definition of Evolution

I did remember but I thought you might have wanted to use the opportunity to revise it.

I’m not sure why you thought it necessary to include (sic) since universal common ancestor is being used in the usual sense in this context as in "the most recent population of organisms from which all organisms now living on Earth have a common descent. https://en.wikipedia.org/wiki/Last_universal_common_ancestor , but perhaps you’re unaware of this usage.

Mitosis is a process of cell division that results in two genetically identical daughter cells developing from a single parent cell. Meiosis, on the other hand, is the division of a germ cell. Nothing unusual here. Without Meiosis and Mitosis I would not have had children. These are mechanisms of reproduction rather than mechanisms of evolution. You might just as well have said “All life on Earth is descended from a Universal Common Ancestor".

But natural selection is a core concept of Darwin’s Theory of Evolution which is why his book is called “On the Origin of Species by Means of Natural Selection, (or the Preservation of Favoured Races in the Struggle for Life)”. This BTW would be a valid criticism of Kerkut’s definition (above). Neutral Theory proposes that a lot of evolutionary change is by genetic drift of mutant alleles that are neutral, however it adds to rather than supplants natural selection as a mechanism of evolution. I still agree with Coyne that natural selection is the main mechanism.


(from evolution.berkeley.edu)

Correct, none worth modifying it for.

Is there “the biology textbook definition”? Or are there many different “biology textbook definitions”? If there was one and only one then surely you would have quoted it.


(Chris) #217

I have two copies of “On the Origin of Species …”. Do I have twice as much information about Darwin’s theory or just two copies of the same information? I think it is the former*. Hence having a higher proportion of an allele does not increase the amount of information. However if the proportion of an allele reaches zero then there is a loss of the information in that allele. Thus microevolution, by your definition, can only result in loss of information, functions, or features.

However many “a relatively large number of changes in allele frequency” is, they would occur over a period of time. Your definition of macroevolution then is simply saying that macroevolution=microevolution + time.

*Correction:
Do I have twice as much information about Darwin’s theory or just two copies of the same information? I think it is the latter. {i.e. 2 copies of the same information.)
Thanks @Lynn_Munter


(Chris) #218

@Lynn_Munter
Although I disagree with you I must compliment you in rising to the challenge of this thread;
Definition of evolution and the distinction between micro/macro

You at least have provided clear definitions for discussion rather than just attacking mine.


(Lynn Munter) #219

I was working outside when I first saw you posted, and I’m afraid this may get lengthy, so thanks in advance for your patience!

I flagged it because it was redundant, the way you were using it. You were quite right to omit ‘Last’ since for this definition we don’t care if they were the most recent or the least recent, but ‘universal’ is being used to mean ‘of all life,’ and since you had just specified ‘All life on Earth,’ it made the reader (me) wonder why you were repeating yourself: maybe you meant something else, like you were trying to claim that all life in the universe is related? “All life on Earth is descended from a Common Ancestor of All Life?”

Word choice is very important when it comes to writing definitions: we want to pick our words carefully to convey exactly the intended meaning, no more and no less, especially if we have reason to believe that people may later argue using our definition as a basis.

In English, when we capitalize words that don’t start a sentence, it’s generally because they’re proper nouns: nouns that you are expected to recognize as requiring some specific knowledge, identifiers. (I live by a superior lake; I live by Lake Superior.) The same thing applies when you capitalize for a concept: you are implying that people had better go read that Wiki article if they want to know what you mean by Universal Common Ancestor, because the meaning isn’t just the simple meaning you would get if you thought about what the words meant.

Proper nouns, even of concepts, should be avoided when trying to write a good basic working definition if at all possible. We want to be able to read and understand the definition without having to flip through other sources to piece it together. So the question I ask is, what information does the Wiki article you linked have that is important to the definition, but that can’t be inferred from the simple phrase ‘an ancestor they have in common?’

If there isn’t much, then we should keep it simple and just say descended from a common ancestor.

The next issue I had was also a grammatical one: “and the main mechanism by which this has happened is by” is ugly and clunky. Plus, what exactly does ‘this’ refer to? ‘Descending?’

The main mechanism by which life descended from its ancestors is . . . you’re right, simple reproduction.

Of course, reproduction doesn’t happen without microevolution, genetic changes and all that, but is that really a main mechanism?

The way I rephrased it to avoid this whole thing was, “and current diversity is due to” which is shorter, more specific, and won’t make grammarians cry into their Cheerios.

“Mutation and Natural Selection.” Again, your capitalization is making me wonder if you mean to refer to a larger concept than the simple meaning of the words, and if your concept definition matches mine. I get the impression you think of Natural Selection as ‘that idea Darwin had that was super wrong’ so I wanted to rephrase it to see if you would recognize the same concept dressed up in different words. It’s not the words “Natural Selection” that are important, it’s the idea that the environment shapes the probability that any given organism will survive or thrive. Like I said, we could use “environmental pressures” to express this concept.

I’m sure there are variations but the standard one I’m familiar with is “changes in allele frequencies,” which I borrowed to define Micro and Macro evolution. But a quick google reveals that there are many more satisfactory definitions out there, so I’m not too attached to it.

Do you mean the latter? :thinking:

Okay, but what if a point mutation results in a start codon being where there wasn’t one before, and now you have a new allele being read and translated until it gets to the next stop codon (those are more common), isn’t that an increase from zero to one? This happens sometimes (see discussions on novel genes) and maybe it turns into a protein that does something and maybe it doesn’t, and maybe that something is beneficial and maybe it isn’t.

Let’s say I had a mutation that doubled my genome. Not an increase, according to you. Now let’s say a hundred generations go by and many other mutations occur so that the two copies are no longer the same information. How is this a loss of information? If a gain in information hasn’t occurred, what could possibly ever qualify as a gain? I don’t understand this argument that mutations don’t cause gains in information, it took me about a minute to see the hole the first time I heard it, and yet people keep on repeating it.

Yes. I am saying that.

I think good definitions are extremely valuable! I also appreciate your willingness to engage in this thread, and I know it can be difficult when you have multiple people arguing against you, so thanks for keeping it gracious!

(Whew, I was right, it got long! :memo:)


#220

There are many definitions, and none of them are perfect.


#221

You have just argued yourself out of the conversation. It would appear that micro and macro evolution works just fine if there is a loss of information, as you define it. It doesn’t require an increase in information (again, as you define it). It’s a bit like defining a home run as a ball hit 3,000 feet, and then proclaiming that no one has ever hit a home run.