Definition of evolution and the distinction between micro/macro


(Jon Garvey) #182

@jpm

Isn’t that to do with changes of fashion, Phil? I seem to remember from school chemistry that “organic” was coined in the days when the chemicals of life were believed to be fundamentally unique, and only later got generalised to “carbon chemistry” when they found they could synthesize them.


#183

In a given population, how many neutral mutations are there that could give rise to a beneficial adaptations with the addition of one more mutation? I would hazard a guess that there are probably a lot of them. You seem to be looking at probabilities the wrong way because you are ignoring just how many possibilities there are. For example, the odds of winning the lottery are something like 1 in 150 million, but it doesn’t take 150 million drawings for someone to win. Do you know why?

Many orphan genes are inherited as non-coding DNA. Something as simple as a single substitution mutation can produce a viable gene promoter that causes the previously non-coding DNA to be transcribed. There are many, many known mechanisms that produce orphan genes. A good review can be found here:

Totz (2011)


(George Brooks) #184

@T_aquaticus and @aarceng:

And let’s not forget that if, hypothetically, there was a population of malaria parasites on the other side of the Earth that was never exposed to Chloroquine, that population could have evolved a resistance to it … and then LOST it again through more genome changes.

Neutral Evolution is only neutral until the environment swings in a new direction, exposing the presence of once neutral features into “downright necessary” features!


#185

In order for these types of claims to make any sense you have to be able to determine every single interaction between any two future mutations and determine if they will be beneficial. At least with today’s technology, such a feat is impractical and nearly impossible. It’s a bit like trying to calculate the odds of the next lottery having a winner without knowing how many tickets have been sold, how many ping pong balls will be chosen, or the number of ping pong balls in the hopper.


(George Brooks) #186

@T_aquaticus,

So… in view of your comment above …

Isn’t the more precise understanding of “Neutral Evolution” one that asks: does the mutation do anything helpful for the life form Right Now?

Does it make any sense to base the definition on “future benefits” ? If this were a future oriented definition, which I would assert it cannot be, a mutation that appears to look VERY irrelevant for the foreseeable future, is only discovered to have a value when a disease mutates into a more virulent form that would be specifically
neutralized by said mutation.

Obviously, it was a neutral mutation (with no known benefit), which is unveiled as an important
adaptation only after an obscure pathogen evolves into a more dangerous form.

In other words: neutral mutations are not forever. They all have a phase during which they express no
known beneficial trait . . . until the day comes when the environment makes a neutral mutation either
a positive or negative influence on longevity or number of offspring.


(Chris) #187

A comment that shows you haven’t really read my posts properly. Why do you think I specifically mentioned the enormous population and short generation time of the malaria parasite. For more on this subject read Behe’s book, “the Edge of Evolution”.


(Chris) #188

You don’t have to look that far. When Chloroquine resistance developed it’s use was stopped. It took about 5 years for malaria to lose resistance to the drug; a lot faster than it took to develop resistance. This shows that the mutation was detrimental and only had a net benefit in the presence of Chloroquine.


(Chris) #189

I won’t. I’ll leave that far more qualified people. Perhaps you should direct your query to AIG.


(George Brooks) #190

@aarceng

I hope we aren’t talking in circles.

Are you saying that the mutation was detrimental, so that it can’t be a neutral mutation?

Or are you saying it is a neutral mutation because, like many others, neutral mutations are frequently detrimental?

The one thing that is obvious is that the benefit of the mutation was invisible until the malaria germ was exposed to Chloroquine. It is only when there is a change in conditions that the beneficial side of neutral mutations, if there are any, are revealed.


(Chris) #191

My purpose was to show similar definitions to my suggested definition in the previous post in which I emphasised common descent and the mechanism of mutation plus selection. i.e.

You will note that I did not include abiogenesis in my definition but both Kerkut and Coyne did.

I think including abiogenesis in the definition of evolution would make an interesting discussion but I deliberately avoided it in my definition because I thought it would be a distraction from the main theme of this thread.


(George Brooks) #192

@aarceng

Fair enough. Now how about making one more crucial change to YOUR definition?:

Where is God? A great many Christian supporters of Evolutionary theory conform their understanding of Evolution to involve God’s engagement in the specific mutations required to for each generation of life.

This shouldn’t seem that strange. If under the rubric of Special Creation, we accept that God makes all his creatures with every gene in a specific place and form, it would be odd to think God then, under all the precision of Special Creation, just evolve in a random walk thereafter.

No less, then, if Christian Evolutionists also believe God engages in the very precise time and place of each generation. Of course Special Creation is conceived as a faster operation … but that’s only from human perception. I am persuaded that for God, fast or slow to humanity, it’s all just an instant to him.

@aarceng, can you cope with God guiding every jot and tittle of evolution?


(Chris) #193

The evidence shows that the Chloroquine Resistance Mutation Cluster is

  • net beneficial in the presence of Chloroquine
  • net detrimental otherwise

Pretty much at this stage. Time to summarise and exit.

My definitions

Evolution (the Neo-Darwinian Theory of) = All life on Earth is descended from a Universal Common Ancestor and the main mechanism by which this has happened is by Mutation and Natural Selection.

Macroevolution: genetic changes that increase genetic information to produce new features or functions.

Microevolution: genetic changes other than macroevolution including change in allele frequncies, loss of genetic information or loss of function of existing genes, gene regulation, etc.


(Lynn Munter) #194

@aarceng, I’m sad to see your definition of evolution hasn’t adapted at all in the face of the many problems with it people kindly took the time to point out and explain to you. It kind of makes it seem like we’re talking to a wall.

But apparently I like the sound of my own voice, because I have to ask now: if there is a gain in information without (immediate) production of function, that should fall under which definition? And if there is a production of new features or functions that happens because of a genetic loss, that is which one again? Your definitions seem to imply that there is no place for either of these possibilities, when they are really very common.

If I were a suspicious soul I might say they were ‘designed’ to be confusing.


(George Brooks) #195

@aarceng,

[1] Looks like you evaded my question: does your definition of Neutral Mutation include mutations that are slightly detrimental?

[2a] Would you agree that some Neutral Mutations are remain neutral forever if they are never revealed to be helpful in any environmental circumstance?

[2b] Would you agree that at least SOME Neutral Mutations can lose their Neutral status when circumstances change sufficiently for the originally-Neutral mutation or allele to provide some Natural Selection benefit?

[3] Your insistence on excluding God from your personal definition of Evolution suggests to me that you are one of the more good-natured Atheist participants found here on BioLogos? I say this not to be pejorative, but to provide contrast with those Christian supporters of Evolutionary theory who believe God can create by means of (miraculous) Special Creation and by means of Evolutionary processes (either by engaging in mutations of the genome or changes in the Natural Selection factors, like sending a Dinosaur-killing Asteroid to hit the Earth).

[4] I think you will find that Neutral Evolution is stochastically adding and subtracting information all the time, and that speciation (which is usually associated with Macro-evolution) is quite possible in either direction:

Was the first tetrapod a fish experiencing a LOSS of genetic information? (reduced gill function, deformed fins)
Was the first proto-whale a mammal experiencing a LOSS of genetic information?
(no more legs, couldn’t rise up on rear limbs)
Is a snake a reptile that experienced a LOSS of genetic information? (no more legs)

The entire fascination with using gain/loss of information as a way of establishing “Devolution” vs. “True” Evolution is a bit of a red herring until we actually know for sure what every gene location actually does.

Your definitions:
Macroevolution: genetic changes that increase genetic information to produce new features or functions.
Microevolution: genetic changes other than macroevolution including change in allele frequncies, loss of genetic information or loss of function of existing genes, gene regulation, etc.


#196

The problem is that your example only looks at one mutation. How many combinations of 2 mutations are there in any given genome that will give rise to a beneficial adaptation? That’s the number you need.


#197

That’s strange since there are strains of plasmodium that already carried one of the potentiating mutations:

“In parallel with the above work, we also performed single‐step selection experiments with CQ on the 106/1K76 line (Fig. 1A). These experiments led to recovery of parasites with the PfCRT K76T mutation (106/176T line) in addition to the 106/176I and 106/176N lines reported earlier (Cooper et al., 2002) (Table 1). In common with the QN‐selected mutant lines, sequencing and genotyping confirmed that the 106/176T line was derived from 106/1K76 and carried only one new mutation in pfcrt, and no changes in the pfmdr1 sequence.”

These neutral mutations were already in the population and weren’t being selected against.


(Haywood Clark) #198

What evidence, exactly? Please point me to all of the relevant evidence.


(Chris) #199

YEC actually.


(George Brooks) #200

@aarceng,

Ahhhh… I see.

So, is there a reason you completely ignore the BioLogos official positions on God’s involvement in Creation, by means of the Miraculous and by means of Evolutionary processes?

You would think you would arrive here and be relieved to discover BioLogos intentionally makes God a part of the Cosmic Order… rather than exclude. Like many of your friends who invest in the I.D. view of the Universe … many BioLogos supporters are eager to describe God’s participation in how Evolution works:

  1. In Special Creation, God positions every gene just so, yes? Do you think God then has no interest or plan for what happens after that? If creatures continue to adapt to a changing world… then each new generation of mutations is relevant, yes?

  2. If environmental factors inflict new harms, or providentially bring new benefits, to ever changing populations, does God stand back, and refuse to engage in the process? That seems unlikely for the Living God, wouldn’t you agree?

  3. So then it should be no surprise if when God wants to create with Evolution, that he should do the very same thing, right?

What are your thoughts on that?


(George Brooks) #201

You know, @aarceng,

Several weeks back, we had some sort of “theologically oriented” fellow here … I don’t think I need to name names.

But he was insistent that scientists were wrong to use a definition of Evolution that excluded God… You know… the usual narrative about “Godless Evolution”… and so forth.

I was sympathetic to his zeal to refute that kind of thinking. So I reassured him that BioLogos specifically crafted statements of belief where they agreed with his position! BioLogos explicitly rejected the idea that Evolution proceeds without God’s engagement (I prefer the term “engagement” to the term “intervene” or “intervention”).

But rather than express his support for BioLogos supporting the very same position he supported, he said that BioLogos couldn’t “qualify” their views on Evolution. They had to accept Evolution… Erroneous Evolution… as the scientists describe it.

When I asked why he was able to reject the Scientists’ version of Evolution … but BioLogos supporters couldn’t … he said it was because God would never use Evolution! (Wow, right?!)

Offlist, I tried to get to the heart of his opinions:

Sometimes I found good ways of asking questions. Sometimes it would be late at night when I would THINK of a better way to ask a question. For example, if I had a chance to do it over, I thought of this one:

Did he mean that God didn’t take a position on how to arrange the genes of Adam and Eve? Or all the wild animals that Adam had to name? When God made the genomes of all these living things … did he close his eyes and hope they would turn out okay? Or did he specifically design exactly what he wanted from their first set of chromosomes?

But then, what next? Did he stop thinking about these things once they started reproducing their kind, one generation after another … for at least thousands of years, right?

Did my correspondent in these discussions mean that God didn’t really care about environmental factors? Was God surprised when an asteroid hit the Earth and wiped out 80% of the life on the planet?

If Evolution is simply environmental factors benefiting some genetic configurations and suppressing other configurations… when did God lose interest in these things?

I have to hit the hay right now … but I look forward to your thoughts on these matters!