Support NeoGAF

[BronzeWolf]

in organisms that don't have any kind of environmental pressure that "differentiates" between mutations, gene mutation is truly random noise and as we all know, random noise averages to zero when not biased

 

[Escape Goat]

I can't believe I'm in the same genus as you guys. It makes me ashamed to call myself homo.

 

[Mgoblue201]

Coleocanth is classified as an order. The ones currently living are classified as different species than the ancient variety. Recently, however, they discovered an insect about 70 million years old that was classified in the same genus as a currently living insect, which is pretty remarkable. Of course, we cannot sequence the genome of these older organisms, and mutations, from what I understand, are constant. Whether those mutations become fixed in a population, and whether they result in large outward changes, depends upon many factors. But the differences are not trivial. I doubt, for instance, that they could successfully mate with more ancient species. Newer organisms have to adapt to different environments; even a bit of random change tends to become fixed.

 

[jaxword]

I guess I never got a reply to the Austrailian Cane Toads article I posted. Oh well...

Bro, I didn't get a reply from the article that specifically said we've been able to create cells in labs.

They're avoiding the things they disagree with.

That's how you argue on the internet when you don't really want to learn anything and just want to troll/rant.

 

[ThoseDeafMutes]

I think humans are an evolutionary anomaly. We are so much more advanced than other animals. Opposable thumbs, large brains... The anomaly factor is where one could say God comes in.

There were several near-human species that existed concurrently in the past, and we are the ones that beat the others out. Humans have exceptional intelligence but that's about it. Every other characteristic we have, another animal has, and they usually do it better. We don't run especially fast, hit especially hard, swim very well, climb trees very well, or have claws to fight with. Plenty of species have opposable thumbs. Several species can recognize themselves in mirrors. Some of our close relatives can even learn sign language.

We have all our eggs in one basket, it just happens to be the best basket in the house. The difference between a human and an orangutan is one of degree, not of kind.

 

[mike23]

silver foxes.

Awesome.

Dear Science,
Domesticated cheetahs please. 50 years seems reasonable, I'll be checking back then.

Thanks

 

[Dead Man]

There's been a selective pressure for them to remain as they are anatomically. They've found a good shape.

They've still evolved though. They'd be gone had they not adapted to any environmental changes, new parasites, diseases and whatever else over that time.

Well yes, but many of them are still the same species, which is what the poster was looking for, I believe.

 

[BronzeWolf]

Coleocanth is classified as an order. The ones currently living are classified as different species than the ancient variety. Recently, however, they discovered an insect about 70 million years old that was classified in the same genus as a currently living insect, which is pretty remarkable. Of course, we cannot sequence the genome of these older organisms, and mutations, from what I understand, are constant. Whether those mutations become fixed in a population, and whether they result in large outward changes, depends upon many factors. But the differences are not trivial. I doubt, for instance, that they could successfully mate with more ancient species. Newer organisms have to adapt to different environments; even a bit of random change tends to become fixed.

never thought of it that way!

My mind has been blown

 

[danwarb]

Well yes, but many of them are still the same species, which is what the poster was looking for, I believe.

I quoted the wrong post. I was replying to the post you quoted.

 

[Mgoblue201]

never thought of it that way!

My mind has been blown

If you're referring to the inability of ancient and recent species to mate, then that's something that just occurred to me, but I don't see how it's not true. Mating should, for the most part, be endemic to the species level. I actually just found, by following the link in Dead Man's post, that Coleocanth is an entire order. However, primate is also an order, and it includes everything from humans to apes to tarsiers. Obviously, primates share a lot in common: opposable thumbs, nails, long development periods, specific types of shoulder joints, strong social bonds, and remarkable intelligence. But there is also wide diversity within it. Our mating range, for example, wouldn't extend much beyond the neanderthals, if even that, and that is considered by many to be a subspecies of homo sapiens.

Of course, I'm not quite sure how they classify fossils; there are a lot of conditions and premises buried in the taxonomical system that I don't fully understand. Even the word diversity requires a specific definition. Are dogs incredibly diverse despite being a part of the same subspecies? Or are they less diverse than they appear? Are coleocanths just as diverse as primates? And do we measure diversity by base pair similarities? Phenotypes? I don't know the answer to any of these questions, but it certainly challenges the idea of human exceptionalism, since we tend to think that our intelligence places us so far away from apes that we might as well be on a different plane.

Anyway, I initially read about the insect in The Economist. It's a short but good read. The fossil is actually 100 million years old.

 

[speculawyer]

Every time I look at my dog, I just can't not think about evolution. We are so related. Head, eyes, ears, nose, mouth, teeth, four limbs, five digits on each limb, basically the same number of bones in our limbs, etc. Sure . . . our common ancestor was a few million years back but I can still see the family resemblance.

Yeah sure . . . I've got a much bigger brain and I can see in color. But his sense of smell is waaaaaaaaaaaay better than mine.

And it is so cool that first through natural selection and then many generations of selective breeding, we are pals. I feed him and he entertains me and guards me. A symbiotic relationship. But one much more meaningful on an emotional level than the one I have with the millions of bacteria that line my digestive system.

 

[Dead Man]

I quoted the wrong post. I was replying to the post you quoted.

I am far from an expert on the subject, I basically just regurgitate doco's I've seen, so no offence was taken anyway.

 

[Zzoram]

Every time I look at my dog, I just can't not think about evolution. We are so related. Head, eyes, ears, nose, mouth, teeth, four limbs, five digits on each limb, basically the same number of bones in our limbs, etc. Sure . . . our common ancestor was a few million years back but I can still see the family resemblance.

Yeah sure . . . I've got a much bigger brain and I can see in color. But his sense of smell is waaaaaaaaaaaay better than mine.

And it is so cool that first through natural selection and then many generations of selective breeding, we are pals. I feed him and he entertains me and guards me. A symbiotic relationship. But one much more meaningful on an emotional level than the one I have with the millions of bacteria that line my digestive system.

When I think of dogs, I think about how we bred grey wolves into the hundreds of dramatically different dog breeds that exist today in only 15,000 years ago. Then I think, if that could happen in just 15,000 years, imagine what could happen in 3,000,000,000+ years.

 

[jaxword]

When I think of dogs, I think about how we bred grey wolves into the hundreds of dramatically different dog breeds that exist today in only 15,000 years ago. Then I think, if that could happen in just 15,000 years, imagine what could happen in 3,000,000,000+ years.

I'm kind of curious as to what the opponents of evolution say about dog breeding.

Humans have taken METICULOUS care to record and specifically alter that species for centuries. In fact, it's sort of creepy how deeply humans have been delving into that particular species and controlling its development. Strange, that obsessiveness we have towards dogs of all animals.

Dog breeding demonstrates a controlled environment producing different traits that are passed on. Isn't that part of the very core of survival of the fittest?

 

[ThoseDeafMutes]

I'm kind of curious as to what the opponents of evolution say about dog breeding.

Something something MICROEVOLUTION something something THINGS CAN NEVER BECOME DIFFERENT KINDS OF ANIMALS something. Something something DOG BREEDING REQUIRED A GUIDING INTELLIGENCE something something DESIGN IMPLIES A DESIGNER.

 

[Mgoblue201]

The largest argument against it is that it hasn't led to speciation. Another is that there hasn't been the development of "novel structures"; to put it another way, dog breeds are simply variations on size, personality, etc. These are somewhat weak arguments. On the face of it, it seems obvious to me that coat colors and patterns, at the very least, are novel features that obviously didn't exist in the wolf. I don't know the genetic provenance of these features: in other words, the genetic changes that would have to occur to give rise to these phenotypes. But I would guess that they're the product of changes after the dog branched off from the wolf.

At this point, creationists will probably move the goal posts and say yeah, but these aren't really new "structures". Of course, that's irrelevant, because at the genetic level you're still working with the same four base pairs. Perhaps they would then argue something a little more sophisticated in that dog breeding doesn't demonstrate the evolution of anything "irreducibly complex", but the intellectual resources needed to make such an argue is, I'm afraid, beyond the purview of most creationists. It's also an argument that can be defeated, anyway, because there are plenty of refutations against it (I posted one example here). In fact, there are good refutations for all of the usual arguments. You can show examples of speciation, the evolution of new features, etc; the things that creationists say don't exist.

EDIT: Actually, creationists try to go on the offensive by claiming that for all dog breeding done, a new species has not resulted. But humans only do the selecting; we cannot control the rate of change. And anyway, it's a two-faced argument. Creationists, on one hand, claim that evolution is too slow to occur, and yet on the other hand they demand examples of evolution that occur on a reasonable human timescale. Most of the dog breeding has only occurred in recent human history.

Of course, I would like to know whether there is any reproductive isolation between wolves and dogs. This is already a phenomenon amply demonstrated in the lab, so it can't be used as a creationist argument, but in fruit flies it was demonstrated to occur in only a few generations. I don't know the degree to which wolves and dogs would freely mate in the wild, at least if there are better options. There is already, for the most part, a large reproductive barrier between them. They will mate occasionally, but the gene flow, I would guess, is rather restricted. I don't know how long it would actually take, however, before they were incapable of breeding together.

 

[ThoseDeafMutes]

The most obvious problem with trying to refute dog-breeding, virus evolution etc for the creationists is that in order to accept that things can become morphologically distinct but that it can never become "a different kind of animal" is that you must have some sort of magical force field protecting the "dogness" of the animal that cannot change, for some reason, even though it's all just DNA.

 

[danwarb]

Given enough time apart, the various breeds of dog will become distinct species. It's already near impossible to cross certain breeds like Beagles and Irish setters.

Anyway, there are plenty of different species that can still successfully interbreed.

 

[ThoseDeafMutes]

Anyway, there are plenty of different species that can still successfully interbreed.

Define "successfully". Under the most common definition of "species" (one that only applies to sexually reproducing organisms, however) has it that it must produce reproductively viable offspring to constitute inclusion as "the same species". On the flipside, two organisms that can reproduce and have viable offspring are members of the same species.

 

[Dead Man]

Define "successfully". Under the most common definition of "species" (one that only applies to sexually reproducing organisms, however) has it that it must produce reproductively viable offspring to constitute inclusion as "the same species". On the flipside, two organisms that can reproduce and have viable offspring are members of the same species.

It think you have just defined the argument so as to be impossible. A mule is a what many would consider a successful interbreeding between two species, although of course it is not fertile (although some females can be, no males are), as the two parents would then be considered of the same species.

 

[ThoseDeafMutes]

It think you have just defined the argument so as to be impossible. A mule is a what many would consider a successful interbreeding between two species, although of course it is not fertile (although some females can be, no males are), as the two parents would then be considered of the same species.

I am aware, lol, hence my asking for clarification. Not really sure why since I already know the answer.

 

[danwarb]

Define "successfully". Under the most common definition of "species" (one that only applies to sexually reproducing organisms, however) has it that it must produce reproductively viable offspring to constitute inclusion as "the same species". On the flipside, two organisms that can reproduce and have viable offspring are members of the same species.

Wolves and coyotes can produce viable offspring for one example. I think any two species producing anything, like lions and tigers, shows a gradual process from viable to infertile to no offspring at all.

 

[Dead Man]

I am aware, lol, hence my asking for clarification. Not really sure why since I already know the answer.

 

[ThoseDeafMutes]

What confuses matters greatly is when you have three or more populations spread out across a large geographic region. We'll call them A, B and C. Population A and B can breed and produce viable offspring, and so can population B and C. However, A and C cannot.

I forget the name for this sort of thing. Biology 101 was a long time ago.

 

[danwarb]

Ring species?

I think it's in the op.

 

[ThoseDeafMutes]

Sounds about right.

 

[Shanadeus]

Wolves and coyotes can produce viable offspring for one example. I think any two species producing anything, like lions and tigers, shows a gradual process from viable to infertile to no offspring at all.

That's because "species" is really a man-made construct I think. In nature you can have slightly blurred lines between what we consider different species.

 

[Dead Man]

That's because "species" is really a man-made construct I think. In nature you can have slightly blurred lines between what we consider different species.

Yeah, the Wikipedia entry on Ring Species I just look up (thanks danwarb) talks about that.

The problem, then, is whether to quantify the whole ring as a single species (despite the fact that not all individuals can interbreed) or to classify each population as a distinct species (despite the fact that it can interbreed with its near neighbours). Ring species illustrate that the species concept is not as clear-cut as it is often thought to be.

 

[danwarb]

The greenish warbler ring species: http://www.zoology.ubc.ca/~irwin/GreenishWarblers.html

The two distinct species both got smaller as they moved north into similar habitats. 10% smaller than the southern forms that connect them, but their songs gradually become more complex around the southern side of the ring.

 

[speculawyer]

The largest argument against it is that it hasn't led to speciation.

Could you really breed a tiny dog like a Chihuahua and some massive dog like a St.Bernard at this point?

Yeah, they are both still dogs . . . but that is hitting the very arbitrary line between species.

 

[teh_pwn]

Why we still got monkeys.

 

[ShadyLurker]

Could you really breed a tiny dog like a Chihuahua and some massive dog like a St.Bernard at this point?

Yeah, they are both still dogs . . . but that is hitting the very arbitrary line between species.

If you attempt it, please use a St. Bernard as the female. The other way around could get kind of dangerous. :lol

 

[Shanadeus]

Why we still got monkeys.

And people call Dawkin arrogant and smug.

So wrong.

 

[Mgoblue201]

Larry Moran's blog contains an interesting discussion on the role of natural selection vs. neutral theory and other non-adaptive mechanisms of evolution. You can go to his blog and simply start reading down the page, but you can also read specifically about Dawkins and natural selection, Richard Lewontin's dissent, and Daniel Dennett's thoughts. In fact, Lewontin's and Stephen Gould's original thesis on the problems of selection inspired the 2010 book What Darwin Got Wrong by Jerry Fodor and Massimo Piattelli-Palmarini, which was thoroughly savaged by many biologists.

I have not read the book and have only read critiques of it such as the one by Jerry Coyne and the one by Ned Block and Philip Kitcher. Though I am sympathetic to the idea that adaptation has been thoroughly oversold and very critical that the conflation of evolution and natural selection has taken hold both in the scientific and popular conscious, the approach of Fodor and Piattelli-Palmarini seem fundamentally wrong.

Could you really breed a tiny dog like a Chihuahua and some massive dog like a St.Bernard at this point?

Yeah, they are both still dogs . . . but that is hitting the very arbitrary line between species.

I'm glad to say that I don't know anything about that, but as long as there are two distinct populations unwilling to reproduce, then reproductive isolation can develop over time. Many times barriers will develop even before two populations are unable to produce offspring together.

EDIT: I am reminded of a dog's behavioral trait that wolves lack: they will follow human cues. This would also surely qualify as new.

 

[Mgoblue201]

It's too bad that Vizion bailed; some of his arguments (meaning, random quotes) had yet to be addressed. I had been meaning to address his point about the rate of deleterious mutations, because I remembered vaguely seeing a refutation somewhere. Just to remind everyone, Vizion quoted geneticist John Sanford, atheist turned theistic evolutionist turned young earth creationist (he's definitely regressing). Here's the quote that was used:

For many decades geneticists have been worried about the impact of mutation on the human population (Muller 1950, Crow, 1997). When these concerns first arose, they were based upon an estimated rate of deleterious mutation of 0.12 to 0.30 mutations per person per generation (Morton, Crow and Muller, 1956). Since that time there have persisted serious concerns about accumulating mutations in man leading to a high "genetic load" - and a generally degenerating population. There has also been a long-standing belief that if the rate of deleterious mutations approached one deleterious mutation per person per generation, long-term genetic deterioration would be a certainty (Muller, 1950). This would be logical, since selection must eliminate mutations as fast as they are occurring. We need to prevent mutant individuals from reproducing, but we also need to leave enough remaining people to procreate and produce the next generation. By this thinking, deleterious mutations in man must actually be kept below one mutation for every three children - if selection is to eliminate all the mutations and still allow the population to reproduce. This is because global fertility rates are now less than 3 children for every 2 adults - so only one child in three could theoretically be selectively eliminated. For these reasons, geneticists have been naturally very eager to discover what the human mutation rate really is!

One of the most astounding recent findings in the world of genetics is that the human mutation rate (just within our reproductive cells) is at least 100 nucleotide substitutions (misspellings) per person per generation (Kondrashov, 2002). Other geneticists would place this number at 175 (Nachman and Crowell, 2000). These high numbers are now widely accepted within the genetics community. Furthermore, Dr. Kondrashov, the author of the most definitive publication, has indicated to me that 100 was only his lower estimate - he believes the actual rate of point mutations (misspellings) per person may be as high as 300 (personal communication). Even the lower estimate, 100, is an amazing number, with profound implications. When an earlier study revealed that the human mutation rate might be as high as 30, the highly distinguished author of that study, concluded that such a number would have profound implications for evolutionary theory (Neel et al., 1986). But the actual number is now known to be 100-300! Even if we were to accept the lowest estimate (100 mutations), and further assumed that 97 % of the genome is perfectly neutral junk, this would still mean that at least 3 additional deleterious mutations are occurring per person per generation. So every one of us is a mutant, many times over! What type of selection scheme could possibly stop this type of loss of information? As we will see - given these numbers, there is no realistic method to halt genomic degeneration. Since the portion of the genome that is recognized as being truly functional is rapidly increasing, the number of mutations recognized as being actually deleterious is also rapidly increasing. If all the genome proves functional, then every one of these 100 mutations per person is actually deleterious. Yet even this number is too small, firstly because it is only the lowest estimate, and secondly because it only considers point mutations (misspellings). Not included within this number are the many other types of common mutations - such as deletions, insertions, duplications, translocations, inversions, and all mitochondrial mutations.

Anyway, as I was searching Larry Moran's site, I found by complete chance the article I had been looking for that refutes this argument. First off, the number of mutations per person per generation that is commonly accepted is 130. One study recently gave an answer of 70, but this study seems to have many problems to it. I also wouldn't trust any of the older studies. We didn't even know how many genes were within the human genome until the 1990s. Until then, scientists were overestimating the number. Creationists love to mine old quotes, so that needs to be said.

However, as Sanford intimates, 130 would still impart too many deleterious mutations. Larry Moran first sets out this problem:

A species cannot afford to accumulate deleterious mutations in the genomes of its individuals. Eventually the number of "bad" mutations will reach a level where most genes have multiple "bad" alleles and it becomes impossible to produce offspring.

This phenomenon is referred to as genetic load. It means that species can only survive if the genetic load is below some minimum value. A good rule of thumb is that there can't be more than 0.1 deleterious mutations per individual per generation but in actual populations this value can be a bit higher.

How do you reconcile this with the known mutation rate in humans? If there are, on average, 130 mutations per individual per generation, then hardly any of these can be deleterious if the species is to survive.

His response? Neutral theory:

Let's think about a typical protein-encoding gene.1 The coding region is about 2,000 base pairs in length and consist of 666 codons. More than half these codons can be mutated to a new codon encoding a different amino acid without severe effects on the function of the protein.2 These are called amino acid substitutions. Of the "essential" codons, many can tolerate mutations that create synonymous codons. Putting these facts together suggests that only about 20% of mutations to protein encoding regions are detrimental. The rest are effectively neutral.

This partially explains why we can tolerate 130 mutations per individual per generation. If only 20% were detrimental then the genetic load is reduced to about 26 mutations per generation.

This is different from merely "neutral junk", though he adds that in too:

Recall that only 20% of mutations in coding regions are likely to be detrimental. That means that the effective target size for detrimental mutations is about 20% x 1.3% = 0.26% of our genome. Out of 130 mutations, only 0.3 per individual per generation will be detrimental.3

Since we are diploid organisms, the 130 mutations in the zygote are spread out over two copies of our genome but almost all of them will be in the chromosomes coming from the father. Every zygote inherits one complete set of chromosomes with hardly any mutations while the other set has less than one detrimental mutation.

Because a large percentage of gene mutations are neutral, and because most of our genome is junk, we can easily tolerate 130 mutations per individual per generation without going extinct.

Of course, Sanford addresses the argument about non-coding regions:

Of all these mutations - what percent are truly neutral? In the last few years there has been a dramatic shift in the perceived functionality of most components of the genome. The concept of "junk DNA" is quickly disappearing. In fact, it is the "junk DNA" (non-protein-coding DNA), which appears to be key to encoding biological complexity (Taft and Mattick, 2003). The recent Taft and Mattick study strongly suggest that the more "junk" - the more advanced is the organism. So mutations within "junk DNA" can hardly be assumed to be neutral!

For most humans, whether religious or not, the notion that humanity is the pinnacle of evolutionary advancement is one of those uncritical assumptions. But from the passages that Vizion quotes, Sanford fails to even define biological complexity and why humans exhibit it. It's the hierarchical view of evolution that I think most biologists would find untenable. There are also no reasons given why the concept of "junk DNA" is quickly disappearing. I'm not going to get into the argument now, but Larry Moran is critical of this assertion because most of our DNA is actually repeating elements and fragments.

He finishes talking about harmful mutations and the genetic load by saying:

Creationists will never understand this because: (a) they believe that modern evolutionary theory is all about "Darwinism" and Darwinian evolution doesn't recognize neutral mutations and random genetic drift, and (b) they can't admit to junk DNA because that's the opposite of what intelligent design would look like.

I eagerly anticipate Vizion coming back to respond to this. I'm sure that he'll come back, right?

EDIT: It should also be said that deleterious mutations that linger can become beneficial later, but I don't know how much of an effect that has on the arithmetic here.

 

[danwarb]

Larry Moran's blog contains an interesting discussion on the role of natural selection vs. neutral theory and other non-adaptive mechanisms of evolution. You can go to his blog and simply start reading down the page, but you can also read specifically about Dawkins and natural selection, Richard Lewontin's dissent, and Daniel Dennett's thoughts. In fact, Lewontin's and Stephen Gould's original thesis on the problems of selection inspired the 2010 book What Darwin Got Wrong by Jerry Fodor and Massimo Piattelli-Palmarini, which was thoroughly savaged by many biologists.

I have not read the book and have only read critiques of it such as the one by Jerry Coyne and the one by Ned Block and Philip Kitcher. Though I am sympathetic to the idea that adaptation has been thoroughly oversold and very critical that the conflation of evolution and natural selection has taken hold both in the scientific and popular conscious, the approach of Fodor and Piattelli-Palmarini seem fundamentally wrong.


I'm glad to say that I don't know anything about that, but as long as there are two distinct populations unwilling to reproduce, then reproductive isolation can develop over time. Many times barriers will develop even before two populations are unable to produce offspring together.

EDIT: I am reminded of a dog's behavioral trait that wolves lack: they will follow human cues. This would also surely qualify as new.

Reading the Dawkins, drift and neutral theory thread. That's good stuff. Thanks for posting.

 

[Kinitari]

It's too bad that Vizion bailed; some of his arguments (meaning, random quotes) had yet to be addressed. I had been meaning to address his point about the rate of deleterious mutations, because I remembered vaguely seeing a refutation somewhere. Just to remind everyone, Vizion quoted geneticist John Sanford, atheist turned theistic evolutionist turned young earth creationist (he's definitely regressing). Here's the quote that was used:


Anyway, as I was searching Larry Moran's site, I found by complete chance the article I had been looking for that refutes this argument. First off, the number of mutations per person per generation that is commonly accepted is 130. One study recently gave an answer of 70, but this study seems to have many problems to it. I also wouldn't trust any of the older studies. We didn't even know how many genes were within the human genome until the 1990s. Until then, scientists were overestimating the number. Creationists love to mine old quotes, so that needs to be said.

However, as Sanford intimates, 130 would still impart too many deleterious mutations. Larry Moran first sets out this problem:

His response? Neutral theory:

This is different from merely "neutral junk", though he adds that in too:

Of course, Sanford addresses the argument about non-coding regions:

For most humans, whether religious or not, the notion that humanity is the pinnacle of evolutionary advancement is one of those uncritical assumptions. But from the passages that Vizion quotes, Sanford fails to even define biological complexity and why humans exhibit it. It's the hierarchical view of evolution that I think most biologists would find untenable. There are also no reasons given why the concept of "junk DNA" is quickly disappearing. I'm not going to get into the argument now, but Larry Moran is critical of this assertion because most of our DNA is actually repeating elements and fragments.

He finishes talking about harmful mutations and the genetic load by saying:

I eagerly anticipate Vizion coming back to respond to this. I'm sure that he'll come back, right?

EDIT: It should also be said that deleterious mutations that linger can become beneficial later, but I don't know how much of an effect that has on the arithmetic here.

Woah, that's some really good insight. To be honest, natural selection was my go-to method for not only explaining Evolution, but understanding it myself. Neutral theory is a pretty new concept to me, and something I'll have to read a lot about.

The last I heard about the mutations per inception, it was at a number like... 40. 130 is a lot. The idea that our genes have built themselves up in a way that they have 'workarounds' to deleterious mutations and genetic load is fascinating, neutralizing mutations is such a crazy idea, but knowing what I know so far about Evolution, I don't see how there are any holes in the concept.

Thanks for the info!

 

[Mike M]

I'm kind of curious as to what the opponents of evolution say about dog breeding.

Off the top of my head...

1. They're still dogs, not a new animal
2. All that variation in their genes was already present, not generated by evolution
3. They were bred by humans, humans are intelligent, ergo it is evidence of Intelligent Design Theory.

It's been my experience that generally when confronted with something like bacterial evolution and dog breeding, even the most ardent creationist will concede some degree of evolution ("God created life with the ability to adapt"), but then move the goal posts and say that whatever example you give them isn't one kind of animal turning into another, then demand that you show them a dog giving birth to kittens.

 

[Raist]

It's too bad that Vizion bailed; some of his arguments (meaning, random quotes) had yet to be addressed. I had been meaning to address his point about the rate of deleterious mutations, because I remembered vaguely seeing a refutation somewhere. Just to remind everyone, Vizion quoted geneticist John Sanford, atheist turned theistic evolutionist turned young earth creationist (he's definitely regressing). Here's the quote that was used:

Yeah, equating mutations hitting the coding region to deleterious is flat out stupid.
First there's silent (conservative) mutations that won't do shit.
Then semi-conserved that are highly likely to not do shit as well.
Then there's missense mutations than can hit a protein without affecting any of its important domains.
And so on and so forth, plus we have 2 functional copies of each gene is most cases.
I can't believe an actual scientist wrote that.

 

[Mgoblue201]

Reading the Dawkins, drift and neutral theory thread. That's good stuff. Thanks for posting.

I actually only scrolled down part way and didn't see any of the Dawkins stuff, assuming that's him, until you mentioned it. It gets even more interesting from there.

Woah, that's some really good insight. To be honest, natural selection was my go-to method for not only explaining Evolution, but understanding it myself. Neutral theory is a pretty new concept to me, and something I'll have to read a lot about.

The last I heard about the mutations per inception, it was at a number like... 40. 130 is a lot. The idea that our genes have built themselves up in a way that they have 'workarounds' to deleterious mutations and genetic load is fascinating, neutralizing mutations is such a crazy idea, but knowing what I know so far about Evolution, I don't see how there are any holes in the concept.

Thanks for the info!

I am by no means an expert on the subject; right now I am particularly interested in learning how scientists prove that something is truly an adaptation (the Jerry Coyne article I linked to earlier offers a good defense of scientists' ability to test natural selection). However, certain limitations must be imposed merely out of caution. I am inclined to think that selection should not be used as the default hypothesis to explain every kind of feature. I don't truly know the degree to which selection plays a role. It depends upon how many adaptations you think exist in an organism (if you go by the amount of evolutionary conservation in a genome, then it's probably significant). However, I question whether every feature we see necessarily needs a selective explanation; just because we can think of one doesn't mean that it occurred.

Anyway, there are a few things meant by neutral (and perhaps quite a few more):

1) Changes at the molecular level can be neutral. This isn't very controversial. There are 20 amino acids and 64 codons that correspond to the amino acids. Therefore, a codon can change without changing the amino acid. 2) A large number of amino acids might change before the protein changes its function. 3) Alleles themselves can be neutral. 4) There are some phenotypes that do not confer any advantage and are therefore product of random change.

Raist in the previous post touched on some of these too. There are a few things that most people can agree upon. A lot of neutral change occurs to the DNA (Moran's contention is that Dawkins, etc. are damning the neutral theory with faint praise by constraining it just to the molecular level). But Moran goes further and says that, "random genetic drift is by far the dominant mechanism at the molecular level and that it even plays a significant role at the level of visible phenotypes."

There is also the stochastic part inherent in natural selection itself:

The population geneticists also discovered that harmful alleles could become fixed by accident, although that turns out to be a rare event. More importantly, they discovered that natural selection has a stochastic component. Beneficial alleles will only become fixed part of the time. The probability depends on the fitness advantage. For example, if an allele has a fitness advantage of 10% then it will only become fixed 20% of the time. In 80% of cases when such an allele arises in a population it will be lost by random genetic drift before it becomes fixed.

As the fitness advantage diminishes, the probability of fixation becomes lower and lower so that alleles with small fitness advantages (<1%) will hardly ever change the species. That's what population geneticists discovered about natural selection.

You can read more about it here.

 

[BronzeWolf]

Stochastic processes! Now there is a word I recognize, I knew there was going to be some kind of predictable randomness somewhere in there.

(I am honestly learning a lot from this thread, keep up the good work)

 

[Raist]

I'm kind of curious as to what the opponents of evolution say about dog breeding.

Bubububut it's microevolution. They're still the same "kind"!

 

[Mgoblue201]

Speaking of dog breeding, I just read yesterday a really interesting story in the March issue of National Geographic about a fox domestication program. I remember first reading about it a few years ago in the book Darwin's Ghost by Steve Jones, but I had no idea that it was still going on. Among many things, the foxes developed within a few generations such characteristics as floppy ears and friendly behavior toward humans. They also had, rarely, thicker vertebrae that were fewer in number, which demonstrates the remarkable malleability of life. The article did not specify whether this had anything to do with the fact that the tail began to curl up and change. But the article also seems to support my previous assertion, at least tentatively, that changes in coat color are the result of mutations.

Unfortunately, Jared Diamond in the book Guns, Germs, and Steel mentions a lot of other animals that we tried to domesticate and failed spectacularly at doing so. His claim is that the wealth of species in Eurasia capable of domestication was a prominent factor in the birth of civilization in that area. Many of the species from Africa and the Americas are nearly impossible to domesticate, let alone tame, even with the tools of modern science. He appealed to a few behavioral and social characterizations on the part of these species to explain why this is true. That foxes can be domesticated within only a few generations through artificial selection is sort of surprising. Then again, they are closely related to wolves, but I haven't seen anyone try to domesticate a jackal.

Anyway, the article is well worth the read, and it's very timely given the discussion here. And it has a picture of a very agitated kung-fu rat.

 

[Scrow]

Speaking of dog breeding, I just read yesterday a really interesting story in the March issue of National Geographic about a fox domestication program. I remember first reading about it a few years ago in the book Darwin's Ghost by Steve Jones, but I had no idea that it was still going on. Among many things, the foxes developed within a few generations such characteristics as floppy ears and friendly behavior toward humans. They also had, rarely, thicker vertebrae that were fewer in number, which demonstrates the remarkable malleability of life. The article did not specify whether this had anything to do with the fact that the tail began to curl up and change. But the article also seems to support my previous assertion, at least tentatively, that changes in coat color are the result of mutations.

sounds like this program http://www.neogaf.com/forum/showpost.php?p=26157126&postcount=956

 

[Mgoblue201]

sounds like this program http://www.neogaf.com/forum/showpost.php?p=26157126&postcount=956

I don't know how I missed that post. It's the same program featured in the National Geographic article.

 

[Kinitari]

Thanks so much Mgoblue. I didn't realize the significance of genetic drift and neutral theory, you've sort of complicated my world a bit, but it's better this way .

I don't know how I missed that post. It's the same program featured in the National Geographic article.

Those foxes are cute, and anyone can own one, it's just super expensive - also you are not allowed to breed them yourself (I guess they're being careful about what genes get passed on).

I also see a lot of effort being put into the domestication of Hyena. Seems like an interesting endeavour, and from what I read, mild mannered and loyal Hyena are already around. I don't know if I want a pet Hyena though, their fucking eyes at night man... gives me flashbacks of me as a kid back in Africa.

 

[jaxword]

Well, the trolls are posting away in the religious thread, so I guess that means they're not coming back here.

Still, good discussion by the people who genuinely tried.

 

[distrbnce]

Man, there's some really great stuff in this thread. I think some of you guys should contribute here: http://www.quora.com/What-are-clever-ways-to-help-someone-understand-the-theory-of-evolution

There's a ton of awesome info in here even for people familiar with evolution.

 

[Raist]

Well, the trolls are posting away in the religious thread, so I guess that means they're not coming back here.

Still, good discussion by the people who genuinely tried.

Don't worry, vizion will probably pop in again in a month or something

 

[tnsply100]

Haven't read through the whole thread, but have there been any predictions of how long it will take for humans to 'evolve' into another species (rather, when would a species appear that would have homo sapiens as its ancestor) - noticeably different appearance, biology, etc?