Poaching making China elephants evolve tuskless

[Rolfe]

Rolfe- I smell a trap...I am not about to teach ma grannie how to suck eggs.

No, it wasn't meant to be a trap, I just wasn't sure what you meant and it sounded interesting.

I don't have set-in-stone ideas about much of this, because I don't think we understand it as well as some people seem to think we do, and I'm always interested in a new way of looking at it that makes some sort of sense. It's just that defining "evolution" as no more than an allele shift in a population doesn't make much sense to me. There's no way to explain "life as we know it" without invoking the appearance of new genes at some point, and I don't see how you can get away from that.

A gene codes for a protein, as a general rule. If you get a mutation in such a gene, you usually simply don't get the protein it's supposed to code from, as a working prospect. So, much of the research into genetic diseases involves first figuring out which protein isn't there, then whereabouts on the gene coding for that protein the mistake has occurred. Very often for any one clinical syndrome of a protein deficiency (for example an enzyme) you might find that there are three or four different point mutations (or something like that) which can be traced through specific families, all of which have the result of nixing the same protein. There's been a huge amount of progress in this area on the heels of the human genome project.

When considering a disease (such as Duchenne's muscular dystrophy) which is severely disabling before reproductive age, it can be seen that as many as 60-70% of cases are in fact new mutations, with no family history. (Duchenne's involves a protein which is very vulnerable to mutation damage in its DNA sequence.) And as I said, often more than one mutation can be shown to lead to the same disease even when it is inherited.

This is how common or garden mutation actually manifests itself in day-to-day biology. Something goes wrong, something important is lost or no longer works properly, and it's all pretty nasty.

The concept of a beneficial mutation which produces a new protein which is beneficial to the organism is a much more difficult one. I'm thinking of antibiotic resistance here. It's possible that this is well understood but I just haven't caught up on current research, but I'm not so sure. Where did β-lactamase come from in the first place? It's not a lot of use to anyone untill you have people using molecules with β-lactam rings to kill bacteria (penicillins). So, was the gene already present in the population, but at very low level, ready to be selected for, or was it a new protein entirely? Does anyone know?

Since penicillin is a natural molecule, then it's possible the gene did spontaneously emerge a very long time ago, and provided a small benefit in enabling the bacteria to survive mould competition, but the selection pressure was never great enough for it to become widely distributed until penicillin use became widespread. However, some antibacterials are not found in nature. And yet, every time we invent something new, these pesky bugs are soon on to it, producing their new proteins which nix the new molecule almost as if the new gene occurs in response to the need for it.

This is of course NOT correct according to the current view of how these things happen. The mutations are random and happening all the time, but only get selected for when the selection pressure is on. So. Given that the apparently new genes for the antibiotic-killing proteins appear pretty soon following the invention of a new antibiotic, this suggests that suitable new proteins probably appear in the bacterial population ever few years irrespective of whether the antibiotic has been invented or not.

But then, we're told that there's negligible metabolic cost to keeping a resistance gene around even if it's not conferring survival benefit. So, why should the necessary gene not have been ready and waiting anyway? Except that the genome of bacteria is quite small, and how many "hopeful" molecules must be sitting around in the bacterial population just waiting for the antibiotic?

This is the point where the argument gets circular, and I realise I don't entirely understand what's being proposed. I wonder if there is a clearer take on this that I haven't come across.

So, it's against the background of realising that my understanding of the process of novel, beneficial proteins arising in a population is not clear, and wondering if anyone else is really any clearer, that I found Soapy Sam's comment intriguing.

Yes, there are genes which do other things than just churn out proteins. Might the clue to understanding this lie there?

Rolfe.

 

[pgwenthold]

It's just that defining "evolution" as no more than an allele shift in a population doesn't make much sense to me. There's no way to explain "life as we know it" without invoking the appearance of new genes at some point, and I don't see how you can get away from that.

We have a word for what you are talking about. It's mutation. However, mutations alone don't "explain 'life as we know it'" either.

Note that mutations (and particularly, the mutations that survive) are certainly a subset of the definition "change of allele frequency."

 

[Rolfe]

We have a word for what you are talking about. It's mutation. However, mutations alone don't "explain 'life as we know it'" either.

Note that mutations (and particularly, the mutations that survive) are certainly a subset of the definition "change of allele frequency."

Because I agree that I don't fully understand evolution at the level of molecular biology, is no reason to address me as if I were a retarded four-year-old.

The point of that post was that in the original OP it was made quite clear that there was no mutation and no introduction of novel genetic material involved in what was happening to the elephants, merely that the tuskless allele was becoming a lot more frequent in the population than it had been in the past. Bill was insisting that this phenomenon alone could be described as "evolution", while I disagreed.

Now, if you're so knowledgeable about mutations, care to explain how a mutation gives rise to a new protein (such as β-lactamase) which was not previously present in the genome of the species, as opposed to nixing one which should be present?

Rolfe.

 

[pgwenthold]

The point of that post was that in the original OP it was made quite clear that there was no mutation and no introduction of novel genetic material involved in what was happening to the elephants, merely that the tuskless allele was becoming a lot more frequent in the population than it had been in the past. Bill was insisting that this phenomenon alone could be described as "evolution", while I disagreed.

It wasn't just Bill "insisting" that this is evolution. It is an example of evolution given the standard biological definition. For example, I posted a textbook definition.

Now, you can stand on your high horse and proclaim that you are the enlightened one and that mainstream biologists are wrong, but recognize that your view is inconsistent with the majority position in the field.

 

[Rolfe]

This is nothing but semantics. I don't care whether you think your position is the mainstream one or not, I think it's unhelpful. So, either agree to disagree or go on posting definitions, it doesn't matter.

Now, we aren't going to agree on the semantics, but we can agree about what we're actually talking about. Do you have a description of the sequence of events which would have to occur at the molecular level in order for a completely new protein to be expressed, one which had not previously existed in the genome of that species? β-lactamase seems to me to be a good example, as that seemed to appear after penicillin antibiotics began to be widely used, and was of course favoured by massive selection pressure as a result of the antibiotic use.

I think the emergence of antibiotic resistance looks like a beautiful example in miniature of what I'm now hesitant to call evolution, but you know what I mean - it doesn't go as far as a new species (yet), but it does look as if truly new properties have been acquired by the organism. I think if this was better understood we'd understand more about evolution on a wider scale. However, if you're content to observe a mere change in allele frequency and declare that you've observed evolution and nothing more needs to be involved, then we won't be asking that question, will we?

Rolfe.

 

[Art Vandelay]

But I was under the impression that evolution was very dependent on the mutation of genes creating new features that were not previously found in a particular species.

So I can see why religious folks and laymen would be skeptical of the claim that this was "evolution in action."

I do not follow. Suppose that, while in Oregon, you met someone who told you that earlier today, he had been in California, and he was driving to Canada. Would you point out to him that driving from California to Oregon is insufficient to reach Canada, and then express skepticism of his claim that Canada was his ultimate goal? If you then accompanied him to Washington, would you insist that you had not, in fact, witnessed him driving from California to Canada, as you saw him in neither place?

If a new mutation caused some elephants to be tuskless, and then this group survived while those with tusks perished, then I think that very few would declare that this was not evolution.

I think this is evidence of indoctrination by IDers. Notice the phrase "new mutation". Clearly, there was a mutation. Your problem is that it occurred before the selection pressure. But why should this matter? Do you think that a mutation that occurred before the selection pressure is an "accident", and therefore doesn't count, while one afterwards is "intentional", and therefore does count?

The idea of genes mutating and creating individuals with features that had previously been unknown, which happened, by coincidence, to be useful, is one that is difficult for many to believe, simply because it seems so fantastical, to us who have not ever observed it.

"Coincidence" is perhaps not the best term. Suppose that you start with one type of organism, then let it mutate until you have several hundred versions. You would expect the fitness of those organisms to vary, wouldn't you? So out of all those different versions, one of them will be more fit than all the others. Is it really a "coincidence" if that version happens to not be the original? Wouldn't it be an even greater "coincidence" if the original were the most fit?

So what is "fantastical" about this? Is it that the current version might not be best? Surely most people are familiar with devices that have improved as years go by, so that can't be it. So is it the issue of "design"? I don't see how this makes a difference. An intelligent designer might think of the improvements more quickly, but why would it be "fantastical" to think that a blind search would eventually accomplish the same thing?

I have to admit that it does stretch the limits of my gullibility to imagine that a mutation happened to confer some benefit countless hundreds of millions of times over the eons, when in modern life it seems that every mutation confers some harm.

Note that mutations are more noticeable the more damage they cause, so the fact that most of the ones you know about are harmful is not surprsing. When someone has a disease, often doctors look for a mutation. But has anyone said "Hey, that Carl Lewis is quite an athlete. Maybe we should see if he has some mutation"?

Combine that with the huge number of mutations, and it is not surprising that so many of them turn out to be beneficial. Remember, life has been around for billions of years. If an organism has a thousand generations a year, just one thousand base pairs, and just one billion individuals, that's 10^24 opportunities for a mutation. That's more than a mole (the number of atoms in 12 grams of carbon).

How does evolution proceed somatically, rather than gametically? The last people I can think of who proposed that were the Lysenkoists in the now-gone U.S.S.R. and a very tiny band of Aussies, led by Ted Steele.

While I suppose one could define evolution to exclude somantic changes, I don't see how it would otherwise be obviously impossible, and so it seems to me that the burden of proof is yours. Isn't it a bit closeminded to accept only genes as possible inheritable factors in fitness?

You can find all the biologists you like who are prepared to use the word "evolution" where only a shift in allele frequency in a population is happening, and this Chartered Biologist (and Fellow of the Institute of Biology) will disagree.

Don't words mean what they are are understood to mean? What meaning does "evolution" have beyond what is assigned to it?

Obviously this process is part of evolution, and evolution couldn't happen without it, but in and of itself I do not define it as "evolution".

Except that it is merely a matter of degree. Every example of evolution comes down to change in allele frequency.

The fact is that every time an individual dies or one is born, the frequency of alleles within the population of that species changes - although only very slightly. However, given this fact, how do you define an "evolutionary" shift? At what point does the normal variation due to the constant change in the individuals making up the population become "evolution"? Perhaps you've just said that all populations are constantly "evolving" under this definition, but in my view if you've said that you've said nothing, and rendered the term almost meaningless.

So is Brownian motion "not really" motion? If we accept Browian motion as "real" motion, must we therefore say that everything is in motion? If everything is in motion, does that mean that the word "motion" is meaningless?

If no new genes are ever introduced (by whatever means), then the amount of change you can possibly get is strictly limited by the genes already available.

So would you say that nothing is evolution unless it involves mutation?

Basically, if allele shift is all there is, evolution as it is normally understood simply can't proceed.

If driving from California to Oregon is all there is, then driving to Canda is not possible. Does that mean that someone driving from California to Oregon is not driving to Canada?

The problem with this is that creationists say that change in allele frequency isn't evolution, but then they turn around and say mutatution isn't evolution, so therefore nothing is evolution, so evolution isn't possible.

This definition is devaluing the concept of evolution. If you are happy to take something as minor and unremarkable as an allele shift and call it "evolution", and trumpet such an event as "evolution in action, yah boo sucks creationists!" then I feel you're setting yourself up for exactly the response you're likely to get.

I agree that we should be careful about trumpeting minor examples of evolution, but I don't think that we should back off of insisting that they are examples of evolution. To some extent, this does "devalue" the concept, but I think that the concept needs to be devalued. If you look at creationist rhetoric, you'll see that "evolution" is used to refer to a virtually miraculous process in which species magically appear. The very triviality of evolution is what makes it so persuasive. How can anyone deny that allele frequencies change? If we allow arbitrary distinction between different "types" of allele frequencies change, we just play in the creationists' hands. Any examples of evolution will simply be called "microevolution", and they will continue to insist that "macroevolution" is not possible.

Evolution is minor. Evolution is unremarkable. The basics of evolution are so obvious that only an idiot could deny them.

In the end, all evolution can be broken into some organisms reproducing, and others dying. If you insist that one organism dying isn't evolution, then how can a million organisms dying be evolution?

That if that's what you mean by evolution, then back to the drawing board pal, because it isn't enough to explain the origins of the teeming variety of life we see around us.

So anything incapable of explaining every single life form should be ignored?

Speciation is a word that constantly pops up in debates like these and in debates with creationists (I notice none of the residential creationists have piped in, yet). We keep discussing if this or that leads to speciation, but do we have a sure-fire definition of species? The most seen is "the ability to produce viable offspring", but that doesn't work for two reasons (at least):

- It has obviously only been tested on a fraction of the species we recognize (not to mention the possible combinations).
- There are in fact some species that can interbreed and produce viable offspring (most notably among fresh-water fishes).

So, do we have a workable definition of speciation?

I think you mean "resident creationists"


As for speciation, it seems to me that "unambiguous" and "workable" are two completely different things. The very nature of evolution prohibits a completely objective classification, as it predicts that every speciation event is continuous, with no sharp demarcation. But that doesn't mean that practically speaking, we can make do with an ultimately subjective definition.

Unfortunately, such a position will enable a creationist to claim that whatever evolution we point to is "just micro-evolution", since, according to his current fancy, a Zebra and a Horse (or whatever) are just "variations" of the same species.

I don't see how that follows. Scientists do not consider the zebra and horse to be of the same species. Simply because we recognize that definitions are artificial, that doesn't mean that anyone can redefine words however they want. And even if we did allow this, a scientist could simply counter that if the zebra and horse are the same species, then every organism is the same species as every other one, and so the issue of macroevolution is irrelevant, as all of evolution is microevolution.

 

[Rolfe]

Of course a shift in allele frequency is part of evolution. Like a chassis is part of a car, and yet a chassis alone isn't going very far.

If driving from California to Oregon is all there is, then driving to Canda is not possible. Does that mean that someone driving from California to Oregon is not driving to Canada?

I don't really understand this analogy. Maybe because I'm on the wrong side of the Atlantic?

I presume that in order to drive from California to Canada, one would normally pass through Oregon. Therefore, if there is indeed a road all the way, then someone driving from California to Oregon might in some sense of the term be said to be driving to Canada. However, if the question is, is it possible to drive from California to Canada, it's not enough merely to point out that there is a great road as far as Oregon.

My interest is really in the molecular biology aspects of evolution. I can't imagine for a second that Darwin wasn't essentially right. Examining his theory it seems self-evidently, blindingly obvious. And then we start to understand more about genetics and inheritance, and it seems as if there is a really neat mechanism which would allow this to happen. Mutation and natural selection. Great!

My problem is that when I try to understand this mechanism at the level of the genome, I hit quite a number of brick walls, and back off in disarray. My next problem is that any attempt to explore these brick walls, to see if there's a way over, or round, or maybe even under, is met by a wave of rationalisations which sould very much like "these are the arguments of creationism, go away stupid."

Shifts in allele frequency in response to a change in the environment is the part of the road which is a six-lane motorway. Easy to understand, easy to demonstrate. However, when this only represents a small fraction of the distance between California and Canada, and much of the rest of the way is uncharted virgin forest, continually repeating that there is this great stretch of motorway here isn't going to get very far as regards demonstrating that it is indeed possible to go all the way.

I was hoping to scare up someone with more information than I had on the less well-surfaced parts of the road. However, it looks as if that's not going to happen in this thread.

Rolfe.

 

[Art Vandelay]

I presume that in order to drive from California to Canada, one would normally pass through Oregon. Therefore, if there is indeed a road all the way, then someone driving from California to Oregon might in some sense of the term be said to be driving to Canada. However, if the question is, is it possible to drive from California to Canada, it's not enough merely to point out that there is a great road as far as Oregon.

Well, the issue ofd this thread is whether it's an example of evolution, not whether it's a proof of evolution.

But going back to the road analogy, if there were some doubt as to whether it is possible to drive from California to Canada, wouldn't driving from California to Oregon be sufficient to, at the very least, establish the presumption that driving to Canada is possible? If someone were to then claim otherwise, wouldn't the burden of proof be on him to explain why driving from Oregon to Canada is different from driving from California to Oregon?

My next problem is that any attempt to explore these brick walls, to see if there's a way over, or round, or maybe even under, is met by a wave of rationalisations which sould very much like "these are the arguments of creationism, go away stupid."

That may be one of the worst consequences of creationism: so much questioning of evolution is motivated by an attempt to discredit it, rather than a genuine desire to learn, that scientists lose their patience for answering people that aren't really interested in listening to the answer.

Shifts in allele frequency in response to a change in the environment is the part of the road which is a six-lane motorway. Easy to understand, easy to demonstrate. However, when this only represents a small fraction of the distance between California and Canada, and much of the rest of the way is uncharted virgin forest, continually repeating that there is this great stretch of motorway here isn't going to get very far as regards demonstrating that it is indeed possible to go all the way.

If I can show that there's a six-lane highway over here, and you claim that there's uncharted virgin forest over there, which one of has the strongest case? If it's uncharted, how do you know it's virgin forest? If the part that we can see is six-lane highway, isn't it reasonable to assume, absent evidence to the contrary, that the rest is as well? I don't understand why you say that shifts in allele freguency is only a small fraction of the distance. What else is there?

 

[pmurray]

Evolution in action

Evolution in action where it can be seen. Marvelous process.

Yeah, I know, we see it on a small scale almost daily with bacteria and viruses..but it doesn't have the same IMPACT that this does.

You see it all the time: dandelions with really really short stems: just right for avoiding lawnmower blades, smaller and smaller fish: caused by generations of fishers throwing the small ones back ...

any others?

 

[pmurray]

I presume that in order to drive from California to Canada, one would normally pass through Oregon. Therefore, if there is indeed a road all the way, then someone driving from California to Oregon might in some sense of the term be said to be driving to Canada. However, if the question is, is it possible to drive from California to Canada, it's not enough merely to point out that there is a great road as far as Oregon.

Hmm. Sounds like you need a map. Have you seen tolweb.org ?

 

[Soapy Sam]

Rolfe-
My understanding is , I strongly suspect , greatly less than your own, especially at the molecular level.

Like you, I get the feeling (In my case from popular science books) that we don't truly understand evolution at a genetic level at all well, which is one reason I'm wary of any definition that is solely genetic.

I personally certainly don't understand it at that level, but I don't think we are alone. I see confusion among the experts too, though you would never know it to listen to them individually.

I've just read a book by Simon Conway Morris for example, which is equally scathing of both "UltraDarwinists" (ie Dawkins ) and Gould's contingent model of evolution. The main thrust of the book is that evolutionary convergence is evident at every level from the molecular to the behavioural, because there are only so many options open to natural processes, physical / chemical / biochemical or behavioural.

He waxes rather theological at the end, raising my sceptical hackles, but it's interesting to see the degree of difference between professional evolutionary researchers who are all firm advocates of Darwinism to varying degrees. (Morris is primarily a palaeontologist.)

I think different researchers, approaching evolution from different angles, see quite different processes, while all thinking they have the "correct" definition;-

eg-one danger in the point mutation / wrong protein / disease view, is the tendency to see genes as "for" a disease or "for" stopping a disease. Clearly that's not so.

Actually I'm not convinced any one gene is "for" anything: Yes it codes for a protein and ( maybe) switches that protein's production on or off. But that on / off switch may be controlled by a different gene (Unless we see genes acting in concert as a single supergene- a program).

The on / off gene may have varied effects in different genomes or in the same genome with exposure to different environmental constraints (food supply for instance).
Imagine British teenagers were all fossilised tonight. (What a wonderful thought).
Do they have different genes from their parents? Of course they do.
So that explains why they are six inches taller and fifty pounds heavier, right?) (Doh!) But if all I had to go on was a fossil skeletal assemblage, I might conclude we are seeing a speciation event here.

In the case of the "Selfish Gene" view, there's a practical limitation: It views things backwards- ie we see critters as vehicles for genes with all the actual selection happening at the gene level.

A fascinating and fruitful shift of viewpoint- and modern biologists can work that way, but to a geologist, genes are just long lost data. (Cretaceous Park notwithstanding). With fossils, you have to work from the (fragmentary) phenotype. Establishing a reliable phylogeny is hard and convergence lurks at every corner.

I have no idea for instance, whether variation in trilobite morphology reflects allelle shifts. It very likely does. Or maybe exactly the same genes gave different body shapes at different water temperatures, or in presence of different nutrients. They're extinct. We have no data. As for the Ediacaran fauna- your guess is as good as a bird in the bush.

On your enzyme question-
http://www.sciencedaily.com/releases/1999/04/990421112504.htm
Ants have been using antibiotics in their intensive farms for ages. Possibly other creatures do too? Could it be that there was antibiotic resistance in bacteria millions of years ago and we just kicked the fairly dormant selection back to the top of the plasmid charts? Was the enzyme already involved in resistance? Or does it have some other, wholly different function which explained it's existence in pre-1930s populations of bacteria? (That would be my guess- but guess is all I can do.)


What is a gene anyway?
What, then , constitutes a "new" gene?
New to the universe? The world? The entire global gene pool? The species? The genome of the individual organism?

If two proteins DO perform the same job, but one of them also improves the ability to play the piano, and the point mutation which creates protein Pianin happens to occur in a Beech Tree- is that evolution?

I, too, worry over questions like this, But I am quite certain that if I shoot every elephant in China stone dead, that is evolution, though not necessarily today . Because when the ice comes back from the north and some of the remaining asian elephants adapt back to a periglacial climate, they will start from a smaller and hence different genepool than would otherwise have been the case. This is Gould's contingent evolution. The fact that the cause was entirely unrelated to any aspect of the Chinese elephant's genes or behaviour is irrelevant. And whether human predation / poaching is "natural" selection or not is definitely a purely semantic question.

Coming at this from the geological side, my definition tends to be long term, empirical and body-based. I know it's just one point of view. I know there are others. It's a tangled bank in nature, but it's a jungle out there in publishing land.

 

[Rolfe]

Imagine British teenagers were all fossilised tonight. (What a wonderful thought).
Do they have different genes from their parents? Of course they do.
So that explains why they are six inches taller and fifty pounds heavier, right?) (Doh!) But if all I had to go on was a fossil skeletal assemblage, I might conclude we are seeing a speciation event here.
....

On your enzyme question-
http://www.sciencedaily.com/releases/1999/04/990421112504.htm
Ants have been using antibiotics in their intensive farms for ages. Possibly other creatures do too? Could it be that there was antibiotic resistance in bacteria millions of years ago and we just kicked the fairly dormant selection back to the top of the plasmid charts? Was the enzyme already involved in resistance? Or does it have some other, wholly different function which explained it's existence in pre-1930s populations of bacteria? (That would be my guess- but guess is all I can do.)

Thanks for a fascinating post, Alistair - these are the only two bits I've time for right now.

I was talking about the increasing height of the human population just the other day while discussing how come human athletes are continuing to break records with monotonous regularity while the best time for the Derby was clocked sometime in the 1920s and nobody even bothers remarking whether a horse is anywhere close to some 50-year-old record.

Partly, the racehorse has already reached its genetic limit of potential - hundreds if not thousands of years of selective breeding and training for one thing does tend to do that, and with a short generation interval too. Partly, humans have only recently (in modern times) started to get really professional about athletics and are getting better equipment and training regimes every year. Partly, humans are prepared to push themselves to levels that would get the RSPCA called if you did it to a horse. But partly it's because we seem still to be recovering from chronic malnutrition occurring in the early decades of the Industrial Revolution. It seems astonishing to me - I would have assumed that as soon as you start feeding the pregnant women properly, and follow that up with good nutrition throughout life, you'd shake off those sort of effects within a generation. But apparently not. The effect somehow has carried on for a good number of generations, and who knows when we'll reach the height that truly reflects our genetic potential (if the junk food culture gets any worse, maybe never!).

But you're right. No way is this evolution, over so few generations. It's a nutritional effect, based in the environment. But looking at it from outside, you could easily be mistaken.

Regarding the β-lactamase. I agree, it is possible that the enzyme was there anyway, I think I said as much in my original post. It would presumably have some value as a defence against moulds. But I don't know and I don't think anyone does. And it's not the only one. There are resistance genes appearing which nix completely synthetic antibiotics. Nicely on cue? I wonder where the reservoir of all these "hopeful molecules" is, just waiting for the day when they'll be needed to confer antibiotic resistance? I don't think anyone knows.

I see an enormous gulf between what we know about mutation, when we can see exactly what happens (substitution of C for G at point wherever on such-and-such a gene, or a frame shift causing an entire segment to be read wrongly or whatever) and exactly what the consequence is (Duchenne's muscular dystrophy or PK deficiency or whatever), and the things it's presumed to be able to do in the uncharted aeons over which evolution happens. I'd like to understand better what we are proposing is happening to the genome at the molecular level just to explain the appearance of one new and useful protein. Unfortunately it doesn't seem to be a popular topic.

Art, are you for real?

But going back to the road analogy, if there were some doubt as to whether it is possible to drive from California to Canada, wouldn't driving from California to Oregon be sufficient to, at the very least, establish the presumption that driving to Canada is possible? If someone were to then claim otherwise, wouldn't the burden of proof be on him to explain why driving from Oregon to Canada is different from driving from California to Oregon?

If I were to point out that there was no sign of a road from Oregon to Canada, on the maps or on the ground, do you really, honestly mean to say that your pointing out that there is a perfectly good road from California to Oregon means that one is entitled to assume that there is also a road from Oregon to Canada, without taking any trouble to show that it actually exists?

scientists lose their patience for answering people that aren't really interested in listening to the answer

Here, you are assuming that there is an answer, and that these martyred "scientists" just can't be bothered to explain.

Indeed no. I'm talking about areas that aren't understood by molecular biologists. This whole thing is much less well understood than you seem to think, and any real scientist will readily admit that. On this forum, I'm noticing a marked propensity for people who aren't scientists to assume that the whole thing is cut and dried, and that because they can see a road to Oregon, it must go all the way to Canada.

Maybe it does. However, I'm interested in exploring the rest of the road, trying to see how much of it is mapped, and whether it actually goes by the route we have tended to assume. If you want to sit there believing that there are no questions left and that anyone asking questions is just some sort of trouble-maker, fine, do that.

I don't understand why you say that shifts in allele freguency is only a small fraction of the distance. What else is there?

You just demonstrated you don't understand anything at all about it anyway.

Rolfe.

 

[Soapy Sam]

I think it's less an unpopular topic than an immensely complex one. Everyone has a different take on evolution and everyone thinks he understands it, until he is asked to explain it.

I think we're all wrong. I also suspect there's more than one way to be right.


At least once, the ice went all the way to the equator. (Or at least the palaomag. indicates the tillites were formed in the tropics. Snowball planet. Global glaciation.)
Right above the tillites are warm water carbonates. Stuffed with Cambrian invertebrates.

I would really like an explanation of that.
And many other things.

 

[Rolfe]

Uh, yes. Now, I actually don't understand why the tillitites and the warm water carbonates are a paradox at all. In fact I don't understand more than one word in three of that sentence.

This is part of the problem. You're a geologist (OK, something close anyway), so you understand that sort of thing well enough to see that there is a paradox. But the solution isn't obvious to you. I'm a biochemist. I understand molecular biology well enough to see that some of the things which are airily assumed to be happening to enable evolution just aren't nearly as simple or as likely as the broad theory implies. But the solution isn't obvious to me. However, the paradoxes aren't at all obvious to people without close familiarity with the subjects in question.

I should no more declare that the tillitites thing is of no consequence because it's obvious that there must be an explanation somewhere, than anyone should declare that the fact that there's a road from California to Oregon proves that there must be one from Oregon to Canada.

But you said you thought that mutation was relatively unimportant to evolution. Care to explain? I can't see how you can get anywhere at all in the long term without that concept or something very much like it. Genes code for proteins. Proteins make bodies. How do you get a significantly different body without novel proteins?

Rolfe.

 

[Art Vandelay]

You just demonstrated you don't understand anything at all about it anyway.

You just demonstrated that trying to have a productive discussion with you is futile.

 

[BillHoyt]

Of course a shift in allele frequency is part of evolution. Like a chassis is part of a car, and yet a chassis alone isn't going very far.I don't really understand this analogy. Maybe because I'm on the wrong side of the Atlantic?

I presume that in order to drive from California to Canada, one would normally pass through Oregon. Therefore, if there is indeed a road all the way, then someone driving from California to Oregon might in some sense of the term be said to be driving to Canada. However, if the question is, is it possible to drive from California to Canada, it's not enough merely to point out that there is a great road as far as Oregon.

My interest is really in the molecular biology aspects of evolution. I can't imagine for a second that Darwin wasn't essentially right. Examining his theory it seems self-evidently, blindingly obvious. And then we start to understand more about genetics and inheritance, and it seems as if there is a really neat mechanism which would allow this to happen. Mutation and natural selection. Great!

My problem is that when I try to understand this mechanism at the level of the genome, I hit quite a number of brick walls, and back off in disarray. My next problem is that any attempt to explore these brick walls, to see if there's a way over, or round, or maybe even under, is met by a wave of rationalisations which sould very much like "these are the arguments of creationism, go away stupid."

Shifts in allele frequency in response to a change in the environment is the part of the road which is a six-lane motorway. Easy to understand, easy to demonstrate. However, when this only represents a small fraction of the distance between California and Canada, and much of the rest of the way is uncharted virgin forest, continually repeating that there is this great stretch of motorway here isn't going to get very far as regards demonstrating that it is indeed possible to go all the way.

I was hoping to scare up someone with more information than I had on the less well-surfaced parts of the road. However, it looks as if that's not going to happen in this thread.

Rolfe.

Rolfe,

I'm perfecting willing to spend the time, but so far I haven't been able to get you off this fundamental error. Evolution is shifts in allele frequency. Period.

Can we start with the Hardy-Weinberg equilibrium to understand why this is so?

 

[Interesting Ian]

Fascinating.

Fascinating?? I see nothing fascinating about it. It's totally disgusting. The world is full of complete bastards who don't give a toss about murdering intelligent beings for a little bit of pocket money.

 

[CFLarsen]

Re: Re: Poaching making China elephants evolve tuskless

Fascinating?? I see nothing fascinating about it. It's totally disgusting. The world is full of complete bastards who don't give a toss about murdering intelligent beings for a little bit of pocket money.

That's not the issue, Ian....

 

[Soapy Sam]

Rolfe- How would you write a new novel without creating new letters? Or new words for that matter?

"Recombination " of existing words , and possibly sentences, (some of them very old), would seem to be the practical answer.

Old words take on a new meaning in a new context.
(Think "Cyberspace"- the old steersmen would be baffled and delighted.) Likewise old genes. (Eyes may have evolved from proteins previously involved in temperature resistance. The process may have happened independently twenty times at least. It works. If it ain't broke...

Some genes are extremely ancient, to the extent we are now locked into using them, even though "better" might exist. The proteins involved in photosynthesis for example seem less than optimal for a world orbiting a yellow dwarf star. But they work.
If ancient genes can still be active in modern forms, performing either the same, or radically different functions, why do we need new ones at all? The world of 70MY ago seems to have been as ecologically complex as today's.

New gene combinations just seem (to me) much more likely to be important, because they probably work well together already. I think in particular any change which leaves embryological development alone , but alters it's timing, is particularly interesting as a candidate for a producer of variation.

This in no way implies that a change at a single location cannot bring significant change. Of course it can. It may well be lethal, but extinction is part of evolution too.


"New and Improved" is a human label. It looks good on washing powder. On software, it looks doubtful and likely to cause problems. On products of natural selection it seems more likely to be a danger signal than a plus. I subscribe to the spanner in the works theory. It might make the engine run better- but it's far more likely to short the battery.

Of course, this innate conservatism, while mine or nature's can't always have been the case. New proteins clearly do evolve and once upon a time there were very few of them. But that's an "origin of life" question. (Sundays only).

 

[Interesting Ian]

Re: Re: Re: Poaching making China elephants evolve tuskless

That's not the issue, Ian....

Perhaps it should be