Evolution: common ancestor?

[Oncedeceived]

All you are doing is telling everyone (other than creationists) that you know as little about evolution as he does.

Oh then Dusty by all means please critique the post and tell us where he is wrong.

 

[Dizredux]

“And let us dispose of a common misconception. The complete transmutation of even one animal species into a different species has never been directly observed either in the laboratory or in the field.” Dean H. Kenyon (Professor of Biology, San Francisco State University), affidavit presented to the U.S. Supreme Court, No. 85–1513, Brief of Appellants, prepared under the direction of William J. Guste Jr., Attorney General of the State of Louisiana, October 1985, p. A-16.

That sounds like a part of the Edwards v Aguillard case in which the US Supreme Court handed the creationists their heads.

Dizredux

 

[Resha Caner]

I suspect here is you may be running into problems. The scientific definition of evolution is change in allie frequencies in a population over time.

The definition of evolution varies a bit. There is even an article on that topic by PJ Bowler: The Changing Meaning of Evolution. So, for example, the Berkeley website defines evolution as descent with modification, and mentions allele frequency secondarily - which to me implies that it is a measure of an evolutionary mechanism: Evolution 101: Descent with Modification

Further, some biologists are promoting epigenetics as evolution (such as David Martin):
Some Evolution May Not Depend on Genes | Epigenetic Changes & Natural Selection | LiveScience

But that's not something I really want to debate, nor do I think it is my "problem" with evolution. I specifically asked the biologists here to give me a definition to avoid semantic arguments, and the definition I got was descent with modification. However, if you would prefer to speak of it as changing allele frequency, that's fine with me. My point would remain the same: Does changing allele frequency explain all the diversity of life? It would seem, by that definition, that the answer is already, "No." So, maybe we don't need to proceed much further.

Time scale, I am not sure what you mean.

I meant that billions of years are not a necessary requirement of evolution. For example, bacterial populations mutate very quickly. So, we can put aside all the debates over geology and the age of the universe. Even if the universe were 30 thousand years old instead of 30 billion, evolution could theoretically have occurred.

From there, as you move into the "how else could it have happened?" arena, some of the first issues are really more in the realm of abiogenesis ... or in the muddy borderline between abiogenesis and evolution - the line between life and non-life and all that.

I'm not sure it can really be said that abiogenesis stopped in the distant Pre-Cambrian. Although science would seem to indicate Earth's environment has undergone significant changes over time, where some environments are consistent with various abiogenetic theories and others are not - it still remains that during many of the extinction/radiation events environment is considered a key factor - and further many of the abiogenetic factors were present during those times. So, it seems plausible there could have been multiple abiogenetic events across the span of time.

Even if there were not, as I said, the life / non-life line is very fuzzy. Biologists would say bacteria are life, archaea are life. But the opinion on viruses is not as certain. Since the Bible doesn't mention single-cell life, doesn't say how God created life ... and given what I think is a very interesting independence by some of the components of our body (antibodies, etc.), it wouldn't bother me to think of various single-cell pools as the source from which different life forms emerged. After all, the evidence seems to be building that multicelluar organisms can emerge very rapidly from single cell pools:
Alga takes first evolutionary leap to multicellularity - life - 06 November 2013 - New Scientist

 

[PsychoSarah]

Were ancestors of mammals always mammals?

No, but attempting to define exactly when the transition happened is pretty much impossible, more because of the fact that people have different opinions on what traits are more important to consider than anything else. Even in the theoretical situation in which we had complete fossils and DNA sequences of every animal that ever lived, we would still have arguments about it.

 

[Loudmouth]

The complete transformation of one species into another is what I asked for and I, as well as the rest of the world, am waiting for.

The production of a new species is exactly what you were given.

Or are you saying that you want an example of evolution producing a new species that shares no features with it's ancestors?

Well-known common species of Chlorella include Chlorella vulgaris, Clorella ellipsoidea, Clorella saccharophila, Clorella pyrenoidosa, and Clorella regularis.

Well known species of Eukaryotes include amoeba, plants, humans, and fish. Since everything from plants to humans are still Eukaryotes and share features that were common to their shared ancestor, would this mean that the entire evolutionary lineage going back to that shared ancestor would not meet your requirement of a "complete transformation"? Does your objection to evolution boil down to our ability to group species through common ancestry?

It depends on which kind of evolution you're talking about. It seems you struggle knowing the difference between a domain, a class or species . . .

My irony meter just exploded.

 

[Loudmouth]

Kindly point out where I said I reject the theory of evolution? Species adapting and changing has been observed since before Darwin. I don't doubt that. That the ToE accounts for all the bio-complexity we see or origin of the species is what I doubt.

You accept that humans and other species share a common ancestor, and that our genomes are the result of the mechanisms of evolution acting on our ancestors that evolved from those common ancestors?

That's a quote? Who said that?

Did I say it was a quote? No.

However, that is what you are implying, is it not? You want us to ignore the observed mechanisms of evolution in favor of supernatural magic, correct?

 

[Loudmouth]

I don't know exactly what Vaccine was trying to say; the difficulty of discrete change versus continuity makes it a difficult conversation. However, for myself I have long wondered whether change in organisms has its limits.

I started a thread where I compared a section of the chimp and human genomes. There were a few differences. I asked creationists to show me which differences evolution could not produce. No creationist even attempted to answer the question. Here is the thread:

http://www.christianforums.com/t7813649/

We keep hearing that evolution has these limits, and yet creationists can never point to them when they are faced with real genetic data. They can't point to a single base difference between humans and chimps that evolution could not produce. They can't point to a single limit that would prevent evolution from producing both humans and chimps from a common ancestor. Not one.

So the real question is why they keep persisting with the claim that evolution has limits when they are irrelevant with how evolution occurs in the real world?

As noted, the examples given for speciation are relatively tiny changes.

The erosion of a mountain by a single storm is relatively tiny. Doesn't change the fact that millions of storms will tear the mountain down.

My reaction to stuff like that is, "Really? That's speciation? How do you know that isn't just the normal span of sagittal crests for that species?" Of course (IIRC) it was all properly correlated with some change in allele frequency, but still. The definition of a species seems so arbitrary as to allow for any change one wants to imagine to be called evolution.

Why would you expect speciation to be an irreversible process that happens in a single generation?

Again, my question is, how do we know there isn't some limit to how much change can occur?

Or how do we know that all mutations aren't a path to universal extinction?

What do you think of the 40 million substitution and indel mutations that separate humans and chimps? Are they causing humans to become extinct?

The answer to your question is right there in the genetic data. Obviously, genomes can change and do so without causing a species to go extinct.

That the diversity of life didn't come from some other mechanism?

Again, that is like asking if we should throw out forensic science because God could plant fingerprints at crime scenes.

So, when examples of speciation are things like a dog-like animal that comes from a dog-like animal, it's hard to accept that as evidence that over the longer span of time dog-like animals came from some reptile-like tetrapod.

Is it much easier for you to accept that a supernatural deity created these species separately? I find it strange that you would be incredulous of observed natural processes while fully accepting supernatural claims that no one has evidence for.

 

[Oncedeceived]

The definition of evolution varies a bit. There is even an article on that topic by PJ Bowler: The Changing Meaning of Evolution. So, for example, the Berkeley website defines evolution as descent with modification, and mentions allele frequency secondarily - which to me implies that it is a measure of an evolutionary mechanism: Evolution 101: Descent with Modification

Further, some biologists are promoting epigenetics as evolution (such as David Martin):
Some Evolution May Not Depend on Genes | Epigenetic Changes & Natural Selection | LiveScience

But that's not something I really want to debate, nor do I think it is my "problem" with evolution. I specifically asked the biologists here to give me a definition to avoid semantic arguments, and the definition I got was descent with modification. However, if you would prefer to speak of it as changing allele frequency, that's fine with me. My point would remain the same: Does changing allele frequency explain all the diversity of life? It would seem, by that definition, that the answer is already, "No." So, maybe we don't need to proceed much further.



I meant that billions of years are not a necessary requirement of evolution. For example, bacterial populations mutate very quickly. So, we can put aside all the debates over geology and the age of the universe. Even if the universe were 30 thousand years old instead of 30 billion, evolution could theoretically have occurred.

From there, as you move into the "how else could it have happened?" arena, some of the first issues are really more in the realm of abiogenesis ... or in the muddy borderline between abiogenesis and evolution - the line between life and non-life and all that.

I'm not sure it can really be said that abiogenesis stopped in the distant Pre-Cambrian. Although science would seem to indicate Earth's environment has undergone significant changes over time, where some environments are consistent with various abiogenetic theories and others are not - it still remains that during many of the extinction/radiation events environment is considered a key factor - and further many of the abiogenetic factors were present during those times. So, it seems plausible there could have been multiple abiogenetic events across the span of time.

Even if there were not, as I said, the life / non-life line is very fuzzy. Biologists would say bacteria are life, archaea are life. But the opinion on viruses is not as certain. Since the Bible doesn't mention single-cell life, doesn't say how God created life ... and given what I think is a very interesting independence by some of the components of our body (antibodies, etc.), it wouldn't bother me to think of various single-cell pools as the source from which different life forms emerged. After all, the evidence seems to be building that multicelluar organisms can emerge very rapidly from single cell pools:
Alga takes first evolutionary leap to multicellularity - life - 06 November 2013 - New Scientist

Good points.

 

[Loudmouth]

The definition of evolution varies a bit. There is even an article on that topic by PJ Bowler: The Changing Meaning of Evolution. So, for example, the Berkeley website defines evolution as descent with modification, and mentions allele frequency secondarily - which to me implies that it is a measure of an evolutionary mechanism: Evolution 101: Descent with Modification

Further, some biologists are promoting epigenetics as evolution (such as David Martin):
Some Evolution May Not Depend on Genes | Epigenetic Changes & Natural Selection | LiveScience

But that's not something I really want to debate, nor do I think it is my "problem" with evolution. I specifically asked the biologists here to give me a definition to avoid semantic arguments, and the definition I got was descent with modification. However, if you would prefer to speak of it as changing allele frequency, that's fine with me. My point would remain the same: Does changing allele frequency explain all the diversity of life? It would seem, by that definition, that the answer is already, "No." So, maybe we don't need to proceed much further.

Why do you think that humans and chimps look different? Is it due to differences in the DNA sequence of our genomes, or is it due to DNA methylation and histone ubiquitination? Do you think that we can take a human genome and produce a chimp from that genome just by changing the pattern of DNA methylation and histone packaging?

I meant that billions of years are not a necessary requirement of evolution.

The Grand Canyon is not a requirement of the theory of erosion. However, this doesn't change the fact that the Grand Canyon is best explained by erosion.

For example, bacterial populations mutate very quickly. So, we can put aside all the debates over geology and the age of the universe. Even if the universe were 30 thousand years old instead of 30 billion, evolution could theoretically have occurred.

Huh?

From there, as you move into the "how else could it have happened?" arena, some of the first issues are really more in the realm of abiogenesis ... or in the muddy borderline between abiogenesis and evolution - the line between life and non-life and all that.

False. We see people rejecting evolution that happened after abiogenesis.

I'm not sure it can really be said that abiogenesis stopped in the distant Pre-Cambrian.

We can say that universally shared traits is not consistent with multiple origins of life.

 

[Loudmouth]

Well, biologists know of some things that limit evolution. Take for example, this list prepared by Ary Hoffman: http://press.princeton.edu/chapters/s3_10100.pdf

Can you name a an evolutionary sequence that would require evolution to go beyond these proposed limits? If not, then why bring it up?

There is also the corollary question: Even if evolution could have produced the variety we observe, did it? IOW, have you ever considered the possibility that maybe evolution is not the only mechanism at work? Maybe the variety of life is due to multiple mechanisms. If so, how would we distinguish them?

Again, you are trying to get us to doubt forensic science because God could plant fingerprints and DNA at crime scenes.

So, I've asked before: What is the essence of evolution? The answer I received, if I understood correctly, is "descent with modification". OK. Now we should be able to recognize what is not evolution. It also allows us to make a list of some things that are not essential to evolution - even though they are debated quite frequently in this forum. The list would include issues of time scale and design.

What is not evolution is a supernatural deity coming down from the sky and magically poofing a new species into being.

 

[Dizredux]

I wrote this the same day as your post but did not get it sent somehow. Oops!


Originally Posted by Dizredux

I suspect here is you may be running into problems. The scientific definition of evolution is change in allele frequencies in a population over time.

Resha

The definition of evolution varies a bit. There is even an article on that topic by PJ Bowler: The Changing Meaning of Evolution. So, for example, the Berkeley website defines evolution as descent with modification, and mentions allele frequency secondarily - which to me implies that it is a measure of an evolutionary mechanism: Evolution 101: Descent with Modification

This is true but keep in mind that the Berkeley site is a very simplified version for someone who is just starting to learn about the subject.

A better source for a scientific definition would be from the National Academies of Science (NAS). Evolution Resources from the National Academies
They define it as I did but using slightly different terms but both mean the same thing.

Evolution: Evolution consists of changes in the heritable traits of a population of organisms as successive generations replace one another. It is populations of organisms that evolve, not individual organisms.

You will find the allele definition in a number of sites. It is considered generally to be the default definition of evolution. I use the NAS one as it is a very high quality resource.

Different definitions for different purposes.

Further, some biologists are promoting epigenetics as evolution (such as David Martin): Some Evolution May Not Depend on Genes | Epigenetic Changes & Natural Selection | LiveScience

I understand this and this is why I carefully wrote

epigenetics is not considered as a mechanism for evolution at this time.

The field of epigenetics is changing very fast and my statement is subject to rapid change but I stand by it for today and today only (grin). What you are talking about may or may not become accepted but it is a fascinating subject.

But that's not something I really want to debate, nor do I think it is my "problem" with evolution. I specifically asked the biologists here to give me a definition to avoid semantic arguments, and the definition I got was descent with modification. However, if you would prefer to speak of it as changing allele frequency, that's fine with me. My point would remain the same: Does changing allele frequency explain all the diversity of life?

Let me try to tackle this. A scientific definition is also called an operational definition. What these try to do give a definition that is repeatedly measurable and this one is. That is different from the Berkeley one but they are aimed at different audiences and purposes.

It would seem, by that definition, that the answer is already, "No." So, maybe we don't need to proceed much further.

No, that is incorrect..

Something that needs to be taken into consideration, the Theory of Evolution is not really just one theory but several interlocking ones. Common descent, descent with modification, natural selection and genetic drift as examples. You have to take these and the others all into account when trying to explain the diversity of life by evolution. None of them will work by themselves and that is what you seem to be trying to do, simplify evolution to a single factor but if you do you will quickly find that it becomes so simple that it is inaccurate.

Diz: Time scale, I am not sure what you mean.

Resha: I meant that billions of years are not a necessary requirement of evolution. For example, bacterial populations mutate very quickly. So, we can put aside all the debates over geology and the age of the universe. Even if the universe were 30 thousand years old instead of 30 billion, evolution could theoretically have occurred.

Evolution is going on right now in real time so major time passage is not a requirement for evolution to occur. For common descent and descent with modification, deep time is likely needed.

From there, as you move into the "how else could it have happened?" arena, some of the first issues are really more in the realm of abiogenesis ... or in the muddy borderline between abiogenesis and evolution - the line between life and non-life and all that.

I'm not sure it can really be said that abiogenesis stopped in the distant Pre-Cambrian.

Abiogenesis could be going on right now. Unfortunately the name for the new life forms is probably "food" or perhaps "lunch". The new organisms would probably be eaten by the existing life. The time for new life to flourish is when there is little or no competition.

Although science would seem to indicate Earth's environment has undergone significant changes over time, where some environments are consistent with various abiogenetic theories and others are not - it still remains that during many of the extinction/radiation events environment is considered a key factor - and further many of the abiogenetic factors were present during those times. So, it seems plausible there could have been multiple abiogenetic events across the span of time.

Most agree that this is possible. There is nothing about the TOE that requires only one line of life. We could have had several but apparently only one survived.

Even if there were not, as I said, the life / non-life line is very fuzzy. Biologists would say bacteria are life, archaea are life. But the opinion on viruses is not as certain. Since the Bible doesn't mention single-cell life, doesn't say how God created life ... and given what I think is a very interesting independence by some of the components of our body (antibodies, etc.), it wouldn't bother me to think of various single-cell pools as the source from which different life forms emerged. After all, there seems to be some emerging evidence that multicelluar organisms can emerge very rapidly from single cell pools: Alga takes first evolutionary leap to multicellularity - life - 06 November 2013 - New Scientist

Trying to get into a definition of life is fraught with peril. The only one that I tend to use is NASA's.

NASA has been using a fairly simple working definition: "Life is a self-sustained chemical system capable of undergoing Darwinian evolution." Brevity forbids any mention of love, friendship, or ice-cold beer.

Resources @ National Geographic Magazine




You bring up some good stuff. Thanks, makes for interesting conversations.


Dizredux

 

[Resha Caner]

Something that needs to be taken into consideration, the Theory of Evolution is not really just one theory but several interlocking ones. Common descent, descent with modification, natural selection and genetic drift as examples. You have to take these and the others all into account when trying to explain the diversity of life by evolution. None of them will work by themselves and that is what you seem to be trying to do, simplify evolution to a single factor but if you do you will quickly find that it becomes so simple that it is inaccurate.

Maybe so, but that doesn't excuse laziness with the definitions either. It creates a situation that allows moving the goalposts when evolutionary theory is challenged. IMO evolution has almost become a useless term that doesn't mean much more than "life changes". I realize some things are in and some things are out, but it begs the question, "Why? On what basis are those discriminations being made?" To make them arbitarily is to make evolution meaningless.

Probably my biggest issue with evolution stems from the idea of common descent - which is why I posted in this thread. As I said early on, scientists don't seem to realize that they appear to be moving the goal posts on this issue. I don't think that is the intent, but that is sometimes the impression given. It's the linchpin to the whole discussion. If common descent were conceded, the question that would immediately follow would be, "Then how much descent with modification occurred vs. how many different trees are there?" The whole thing starts to come apart.

Abiogenesis could be going on right now. Unfortunately the name for the new life forms is probably "food" or perhaps "lunch". The new organisms would probably be eaten by the existing life. The time for new life to flourish is when there is little or no competition.

That's one of the hypotheses. Are you aware of anything that supports it? It is interesting that most of the major radiation events were accompanied by an extinction event (a reduction in whatever predation on abiogenesis was happening). IOW, extinction is one reason abiogenesis would be likely during those times.

Think about metamorphosis. While the larva is developing it is very vulnerable. As you say, it is lunch. But the species survives. How? By producing more larva than the prey can eat. That is why DogmaHunter's comment was so interesting to me - that he would suspect that when abiogenesis happens, it produces a lot.

Again, it doesn't seem there is anything in that particular step that rules out rapid emergence as an alternative to evolution.

Most agree that this is possible. There is nothing about the TOE that requires only one line of life. We could have had several but apparently only one survived.

On what basis do you say that? Similarity is not sufficient evidence for such a claim.

Trying to get into a definition of life is fraught with peril.

It is.

The only one that I tend to use is NASA's.

"Life is a self-sustained chemical system capable of undergoing Darwinian evolution."

No offense, but that's a terrible definition - circular in the worst way. You've now embedded evolution in the definition of life. So, anything that doesn't evolve is not life?

 

[Loudmouth]

Maybe so, but that doesn't excuse laziness with the definitions either. It creates a situation that allows moving the goalposts when evolutionary theory is challenged. IMO evolution has almost become a useless term that doesn't mean much more than "life changes".

That is only because creationists strive to create this confusion.

I realize some things are in and some things are out, but it begs the question, "Why? On what basis are those discriminations being made?" To make them arbitarily is to make evolution meaningless.

They aren't making them arbitrarily. Heritable traits are a basic feature of evolution, and it is changes in heritable traits that it focuses on. Epigenetics, for example, do involve traits that are passed on. However, these traits only last for a few generations so they don't have the same effect on long term species evolution as traits based on DNA sequence.

Probably my biggest issue with evolution stems from the idea of common descent - which is why I posted in this thread. As I said early on, scientists don't seem to realize that they appear to be moving the goal posts on this issue. I don't think that is the intent, but that is sometimes the impression given. It's the linchpin to the whole discussion. If common descent were conceded, the question that would immediately follow would be, "Then how much descent with modification occurred vs. how many different trees are there?" The whole thing starts to come apart.

How are the moving the goal posts? Why should they throw out common descent when it is supported by mountains of evidence?

That's one of the hypotheses. Are you aware of anything that supports it? It is interesting that most of the major radiation events were accompanied by an extinction event (a reduction in whatever predation on abiogenesis was happening). IOW, extinction is one reason abiogenesis would be likely during those times.

Do you understand that life has contaminated almost every environment with enzymes that immediately breakdown RNA molecules? Before life, this wouldn't have been the case. This is what we are talking about. Life has changed the environment to such an extent that it makes abiogenesis much less likely than in an abiotic environment.

Think about metamorphosis. While the larva is developing it is very vulnerable. As you say, it is lunch. But the species survives. How? By producing more larva than the prey can eat. That is why DogmaHunter's comment was so interesting to me - that he would suspect that when abiogenesis happens, it produces a lot.

There aren't ubitiquous enzymes in the environment that kill pupae in a matter of seconds like there is for RNA, and to a lesser extent DNA and protein.

Again, it doesn't seem there is anything in that particular step that rules out rapid emergence as an alternative to evolution.

It is the same logic that rules out God planting DNA and fingerprints at crime scenes.

On what basis do you say that? Similarity is not sufficient evidence for such a claim.

Why isn't it sufficient?

No offense, but that's a terrible definition - circular in the worst way. You've now embedded evolution in the definition of life. So, anything that doesn't evolve is not life?

We could remove evolution from the definition and redefine life as imperfect replicators that compete for limited resources. It's just more effecient to say evolution.

 

[Dizredux]

Maybe so, but that doesn't excuse laziness with the definitions either. It creates a situation that allows moving the goalposts when evolutionary theory is challenged. IMO evolution has almost become a useless term that doesn't mean much more than "life changes". I realize some things are in and some things are out, but it begs the question, "Why? On what basis are those discriminations being made?" To make them arbitarily is to make evolution meaningless.

Definitions are useful things but do not restrict reality. Different definitions can be chosen for different purposes and are simply aids to communications.

Probably my biggest issue with evolution stems from the idea of common descent - which is why I posted in this thread. As I said early on, scientists don't seem to realize that they appear to be moving the goal posts on this issue. I don't think that is the intent, but that is sometimes the impression given. It's the linchpin to the whole discussion. If common descent were conceded, the question that would immediately follow would be, "Then how much descent with modification occurred vs. how many different trees are there?" The whole thing starts to come apart.

Keep in mind that for the most part scientists are talking to scientists and all recognize what is being done, the rules of the game so to speak. It is trying to communicate to the general public is where sometimes confusion comes. General definitions or descriptions are good for teaching the public but not all that effective in scientific discussions. In science, the definition of evolution as a function of allele frequencies is an accurate and good one but it can be somewhat confusing to the lay public ("What the dickens is an allele?"). Descent with Modification and Common Descent are good terms but are not an exact definitions. From all that I am able to tell, most papers use the allele definition unless another is more appropriate of the subject of the paper.


(New life serving as food)

That's one of the hypotheses. Are you aware of anything that supports it? It is interesting that most of the major radiation events were accompanied by an extinction event (a reduction in whatever predation on abiogenesis was happening). IOW, extinction is one reason abiogenesis would be likely during those times.

I agree and that is what I was talking about. While multiple forms of life could have existed but for whatever reason so far only one strain of life chemistry has been found and that form has identical DNA/RNA structure (to the best if my knowledge). Pretty good evidence but as in all science not proof.

Think about metamorphosis. While the larva is developing it is very vulnerable. As you say, it is lunch. But the species survives. How? By producing more larva than the prey can eat. That is why DogmaHunter's comment was so interesting to me - that he would suspect that when abiogenesis happens, it produces a lot.

Leaving lots of descendants is a very successful replication strategy but not the only one.

Again, it doesn't seem there is anything in that particular step that rules out rapid ergence as an alternative to evolution.

There is nothing as far as I am aware that rules out multiple paths to life. It is just that none of the others have been found so far.

On what basis do you say that? Similarity is not sufficient evidence for such a claim.

Just similarity is not very useful as we keep telling ED. It is the patterns of the twin nested hierarchies that, to me, are the most powerful evidence for evolution as we know it. There are other evidences but to my mind this is the most conclusive.


NASA's working definition of life:

No offense, but that's a terrible definition - circular in the worst way. You've now embedded evolution in the definition of life. So, anything that doesn't evolve is not life?

Don't argue with me, argue with NASA. The NASA definition is a working one. Rough and ready and easily measurable and not intended as anything ultimate. Working definitions are not for that purpose.

Again quite interesting,


Dizredux

 

[Resha Caner]

In science, the definition of evolution as a function of allele frequencies is an accurate and good one but it can be somewhat confusing to the lay public.

It doesn't confuse me. I suppose I should have clarified. When I said I was a layman, I meant I'm not a biologist. I do, however, have an MS in engineering, so I know something of science. Regardless, there are plenty of other lay people here who seem to understand what an allele is, so I don't see that as a hindrance. As I said, if that's what you want to use for our conversation, that's fine.

But such a definition excludes epigenetics. As such, if one finds epigenetics is a significant source of diversification in populations, one can't just arbitrarily pull epigenetics under the evolutionary umbrella. What would be the motivation for doing so? Why should a biologist who accepts allele frequency as the definition of evolution then object to saying epigenetics is not evolution? That in no way negates epigenetics as a biological process. It doesn't invalidate the evidence supporting epigenetics nor does it invalidate evidence supporting allele changes.

So, the desire to keep pulling mechanisms under the evolutionary umbrella must have some other motivation. To say, "Well, because it's evolution," would be a logical fallacy - a circularity. If evolution is going to encompass both changes to the DNA and epigenetics, then the definition must somehow span both of them.

It's not a matter of dumbing things down for the public, nor is it a matter of efficaciousness (I happen to think "descent with modification" is a very good definition).

I guess I expect some rigor.

 

[Resha Caner]

Do you understand that life has contaminated almost every environment with enzymes that immediately breakdown RNA molecules? Before life, this wouldn't have been the case. This is what we are talking about. Life has changed the environment to such an extent that it makes abiogenesis much less likely than in an abiotic environment.

What is the typical lifespan of those enzymes?

What is the typical radius of dispersion?

What are the barriers they cannot penetrate, or the environments that dissolve them? I assume the life that has survived has a defense against them.

 

[PsychoSarah]

What is the typical lifespan of those enzymes?

What is the typical radius of dispersion?

What are the barriers they cannot penetrate, or the environments that dissolve them? I assume the life that has survived has a defense against them.

Depending on the environment, enzymes have variable lifespans. At ideal temperatures, etc, some can last practically indefinitely.

 

[Resha Caner]

Depending on the environment, enzymes have variable lifespans. At ideal temperatures, etc, some can last practically indefinitely.

I'm sure one could design ideal conditions to make them last, but that wasn't really the question. Upon a quick Google search, the source that pops up over and over again is: Enzymes in the Environment: Activity, Ecology and Applications by Richard G. Burns and Richard P. Dick.

In only the 2nd paragraph of the Preface comes the statement, "Although most extracellular enzymes released from the cells are rapidly denatured or degraded, some will survive, if only for short periods."

That's when I had to stop and say: OK, I'll need someone to interpret for me or this is going to look like quote mining.

 

[Dizredux]

But such a definition excludes epigenetics. As such, if one finds epigenetics is a significant source of diversification in populations, one can't just arbitrarily pull epigenetics under the evolutionary umbrella. What would be the motivation for doing so? Why should a biologist who accepts allele frequency as the definition of evolution then object to saying epigenetics is not evolution?

As I understand the field, epigenetics is seen as part of genetics but not necessarily evolution. does not, as far as we know, work with deep time where evolution does.

That in no way negates epigenetics as a biological process. It doesn't invalidate the evidence supporting epigenetics nor does it invalidate evidence supporting allele changes.

When epigenetics is shown to have an impact more than a few generations then perhaps the definition of evolution will have to be changed. Until then I suspect the working definition will remain.

So, the desire to keep pulling mechanisms under the evolutionary umbrella must have some other motivation.

What other motivation? I am not sure of what you are trying to get at here.

To say, "Well, because it's evolution," would be a logical fallacy - a circularity. If evolution is going to encompass both changes to the DNA and epigenetics, then the definition must somehow span both of them.

Yes and when that time comes, that is probably going to happen but for the time being I don't see where epigenetics is considered as part of evolution.

It's not a matter of dumbing things down for the public, nor is it a matter of efficaciousness (I happen to think "descent with modification" is a very good definition).

It is a very good definition but it is of little value in a lab setting deciding if evolution in a population of organisms has occured. That is what the operational definition is for.

I guess I expect some rigor.

You might consider doing some research on the term operational definition. If you have not done this, you are not practicing methodical rigor.

Dizredux

 

[Loudmouth]

What is the typical lifespan of those enzymes?

Years.

What is the typical radius of dispersion?

Every drop of water. In the lab, you have to spend a lot of time and money to rid your water of RNases, and even then you still have to worry about it.

What are the barriers they cannot penetrate, or the environments that dissolve them? I assume the life that has survived has a defense against them.

A good barrier is an evolved cellular membrane which new life would not have.