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Author Topic:   Is there really such a thing as a beneficial mutation?
crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 3 of 223 (342870)
08-23-2006 10:42 PM
Reply to: Message 1 by Faith
08-23-2006 9:07 PM


Is it possible that at least one form of "mutation" is not a "mistake" but a normal predictable method of producing variations in the normal processes of reproduction, just as the process of mixing of alleles is?

Well, all evolutionists would argue that mutations are one of the normal methods of producing variant individuals during reproduction, in addition to sexual recombination (what you've referred to as "allele mixing.")

I think it's important not to get hung up on the idea that mutations are "mistakes." Mutations are unpredictable changes in DNA that occur because DNA replication processes in cells are not perfectly faithful; they sometimes introduce sequences in the copy that were not present in the original, or delete sequences.

The majority of those changes have no effect on the phenotype of the resulting individual. Many cause effects that hamper the individual's success in reproduction. A select few have the opposite effect - the affected individual reproduces more offspring than non-affected individuals.

What is a "beneficial" mutation REALLY, and

REALLY, it's a mutation that is statistically connoted with an increase in reproductive success in individuals that carry the allele.

If you think that's a definition that's fairly hard to test in most cases, well, you'd be right. That's why it's difficult, most of the time, to point to a really good example of a beneficial mutation - one that "feels" beneficial.

A lot of the time, a beneficial mutation is the deactivation of a gene that was beneficial in an old environment, but detrimental in a new environment. One such mutation would be lactose tolerance - the ability of some adults to consume dairy products containing lactose long after childhood. In an environment like Africa, maturity-onset intolerance is weaning aid that gets a child on adult food as soon as possible. We see the same behavior in almost all mammals.

But in an environment with domesticated mammals that can be milked, lactose intolerance becomes a barrier to accessing an readily avaliable, nutritious food source. That's why we see lactose tolerance largely among only the decendants of people from dairy cultures - India, Northern Europe, etc - and intolerance among decendants of people whose cultures had no such milkable domestic animals.

Both lactose tolerance and lactose intolerance are beneficial under the right conditions. That's what makes it so hard to make blanket pronouncements about what is a beneficial or detrimental mutation. It's always relative to environment.

In this case the fact that most of them have no effect at all just underscores the gradualness of the deterioration process, and the occasional apparently beneficial mutation is a mere anomaly that occurs in the nature of the chemistry involved.

This doesn't seem to me to represnt a fundamental difference about the existence of beneficial mutations. You seem to be agreeing that they occur; they just don't occur all that often, so they can be ignored as a source of evolutionary change.

But it seems to me that evolution's selective mechanisms make even rare beneficial mutations unignorable. Even if they happen just a little bit that's enough for selection to weed out degeneration and promote adaptation.

We're talking about THE supposed "driving force" of evolution, the system that brought us the eye and the hand and the human brain and in fact the whole stupefyingly elegant system of genetic coding -- it makes your jaw drop to begin to appreciate the mathematical precision involved in the coding process that creates proteins that actually do things in the cells of living things that make all functions possible -- except for those "mistakes" of course.

Well, sure. The eye with its inefficient, backwards retina that operates so poorly in low-light; the hand with its system of tendons that are responsible for carpal tunnel syndrome and its fingers with their restricted range of independant movement; the brain with its redundant, even contradictory subsections and famous inability to effectively heal.

And honestly? There's not that much precision in the genetic code. The reason so many mutations are neutral is because you can typically alter a considerable portion of the protein without altering its active site. And molecules are springy, flexible. The tolerances don't have to be so tight.

It turns out that the more you look at the natural world, the less you see finely tuned living machines, and the more you see bodies that almost don't work. That are mismatched, backwards, clumsy. Systems that are twice as complicated as they need to be. "Unintelligent design", in other words.

The half-assed functioning of the natural world? Easily within the reach of random mutation and natural selection, in my view.

So it is still a possibility in my mind that there is a method to the madness of SOME so-called "mutations" that is really part of the normal reproductive system rather than merely a mistake and could somehow be part of the explanation for (micro) evolution since the ark.

We've done studies to try to see if adaptive mutations are actually driven by environmental pressures, rather than being just random advantages. The studies pretty uniformly show that environment doesn't drive advantageous mutations. They just happen at random. For instance, a statistically random number of bacteria will develop resistance to antibiotics (for instance) even in an environment where antibiotics aren't present.

I hope some of that helps. Honestly I think you've got the basics, but a little more familiarity with the material would help, and (I hate to get confrontational like this) it would help still further if you were looking at this material with an eye towards what it could tell you about the natural world all by itself rather than looking for ammunition to use against evolutionists.


This message is a reply to:
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crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 16 of 223 (342967)
08-24-2006 11:55 AM
Reply to: Message 10 by Frog
08-24-2006 10:00 AM


Information isn't really on-topic in this thread
What is, is how a net gain of genetic information come about?

By mutation. If you change the old information, by definition, the information you have now is new.

Moreover, gene duplication can occur as well. If before you had 1 copy of a gene, and now you have two, by definition you have a net gain of information, because you have an additional amount of information - 1 gene's worth - that you didn't have before the mutation.

That is, the ‘wing-making’ information is lost or scrambled in some way.

Typically information is not lost or scrambled in this way. Typically, mutations such as these occur in the promoter sequence of the gene, which results in it's inactivation. The information is still there; it's merely ignored by the organism.

Are there ‘good’ mutations?

Sure. For instance - immunity to arteriosclerosis, which has arisen by mutation in a small population in Italy. Or a recent mutation that results in comic-book-like superdevelopment of muscles, even in infants.

CCR5 connotes a near-immunity to HIV, and again, this is the result of a mutation.


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crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 20 of 223 (342972)
08-24-2006 12:06 PM
Reply to: Message 14 by Faith
08-24-2006 11:34 AM


most of which functions without the compromises and trade-offs accepted as beneficial mutations.

What, really? You can see color in nearly complete darkness? (You could if your retinas were right-side out instead of backwards.) You can eat saturated fats all your life and not have a heart attack? (You could, if you weren't able to digest fruits and vegetables at the same time.)

You have gills? Wings? Hooves? A spleen that can store extra blood to supply during periods of intense physical activity?

You don't have a pelvis wider than your basic stance? If you're a woman, you do. There's a reason why the majority of knee injuries and knee surgeries are performed on women - they don't have straight legs. Their hips splay out, which puts lateral stresses on their knees.

You don't suffer from back trouble, as a result of having an upright posture with a spine designed to act as a horizontal suspension bridge? In the vertical position, the spine is about as sturdy as a stack of quarters - because that's just how it's built.

The human body is nothing but a set of trade-offs. It's designed for an environment. It's maladaptive for other environments.

I get that mutations do happen that have a beneficial function although they also have destructive properties.

What's the destructive property of CCR5? Or the destructive property of lactose tolerance in humans?


This message is a reply to:
 Message 14 by Faith, posted 08-24-2006 11:34 AM Faith has replied

Replies to this message:
 Message 21 by Faith, posted 08-24-2006 12:21 PM crashfrog has replied

  
crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 22 of 223 (342980)
08-24-2006 12:27 PM
Reply to: Message 21 by Faith
08-24-2006 12:21 PM


Didn't mean to take an abrupt tone, by the way. I'm at work and so I have to be brief. :)

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crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 46 of 223 (343065)
08-24-2006 5:33 PM
Reply to: Message 26 by mjfloresta
08-24-2006 2:03 PM


Re: Beneficial mutation
All observed variation however, is variation of the same body plan - not variation of the body plan.

Well, at the unicellular level, we've seen immense variation of body plans in response to various environmental pressures.

At the multicellular level, though, there really isn't any variation on body plans. Almost every single species shares the same body plan; the segmented worm + legs.

You too. A casual look at your spine should be enough to prove that you're nothing but a variation on a segmented worm with legs. Your embryological development occurs in linear segments. And if that's not enough, we can delve into the genome, and see that the genes that control body plan - the homeobox genes - are almost identical in structure and function to the same class of genes throughout the animal kingdom.

But you're right. All organisms are tied down to the segmented worm, because the segmented worm is a very robust archecture, and it's easy to model genetically - the head is the beginning of the gene, and the tail is the end of the gene.

Developmental genetics is quite facinating, actually, if you've ever heard of DNA as "the blueprint of life" and wondered exactly how to read the blueprint. Homeobox genes are that blueprint, and we're aware of thousands of mutations that affect the development of different segments of that segmented worm archetecture. That's what those Drosophila experiments are all about.

Never has there been observed the introduction of the genetic material required for novel body plans and organs which have previously been present in that organism.

I think there's a typo here. If they were previously present how can they be novel?


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crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 142 of 223 (343311)
08-25-2006 11:46 AM
Reply to: Message 99 by Faith
08-25-2006 2:21 AM


No such list
Instead of a continuation of the back and forth about the creo interpretation vs the evo interpretation, maybe you could launch this thread in the direction of a discussion of the actual particulars of some of the mutations known as beneficial. Perhaps a list of all known ones at some point. Or maybe Crash could offer that.

They happen so often that there's not really a list. Beneficial mutations aren't really a significant thing to evolutionists, because we know they happen all the time; to the extent that we can count on them to be happening.

It's a basically settled issue, so no one bothers to keep track anymore. Anyway, as Percy said in the other thread, every gene in every organism, every cellular function, every protein, every regulatory structure, everything, all started out as beneficial mutations.

It's like you're asking me "show me a list of all the atoms that have ever been observed." I mean, we're way beyond that point. Maybe in the early days of particle acceleration and bubble chambers it would have been relevant to keep a list, keep track, but that was almost a century ago. Nowadays, physics undergrads look at atoms and play with accelerators. Nowadays, biology undergrads observe beneficial mutations in petri dishes and bioreactors.

The examples we've provided aren't exhaustive; they're just spectacular. They're the really compelling, interesting examples that are easy to communicate to laypeople because the effects are very obvious and much easier to explain than something like "epigenetic silencing of MGMT by promoter hypermethylation may lead to a particular genetic change in human cancer, specifically G to A transitions in the K-ras oncogene."

We've got quite a few beneficial mutations on the table already. Why don't you pick one and we'll cover how it works, how we know it's a mutation and not a result of sexual recombination, and why we believe it to be beneficial.


This message is a reply to:
 Message 99 by Faith, posted 08-25-2006 2:21 AM Faith has replied

Replies to this message:
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crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 147 of 223 (343319)
08-25-2006 12:04 PM
Reply to: Message 134 by Faith
08-25-2006 11:07 AM


Re: Trade-offs
But what if Biblical creationism is true instead? Then everything is deteriorating, human beings are deteriorating

But that wouldn't last for very long. Anybody who deteriorated even just a little bit would be immediately outcompeted by anybody who hadn't yet deteriorated. Natural selection would act to preserve only those individuals who just hadn't happened to deteriorate genetically, even if they were only a small portion of the individuals. They would rapidly outcompete their deteriorating peers.

And moreover - we don't see any evidence of this deterioration. IQ's go up, in every population around the world, every year. So much so that we have to renormalize the IQ scale every few years. (It's all but impossible, now, to compare contemporary IQs with historical IQs for this reason - the scales are so different. IQ 100 now is much, much smarter than IQ 100 back then.) Life expectancies go up from historical records. Diseases that once culled two thirds of Europe are now little worse than the flu for most individuals.

You claim this deterioration, but I don't see it. Human civilization marches forwards, not downwards. Diseases are conquered, problems are solved, challenges are met, and many who would would have died young in ages past enjoy long and fruitful lives today.


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Replies to this message:
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crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 152 of 223 (343334)
08-25-2006 12:32 PM
Reply to: Message 151 by Percy
08-25-2006 12:18 PM


Re: Trade-offs
I agree with Faith's earlier argument that the genome of the human race is over time becoming less and less robust (I know that's very non-specific, but I think the meaning is clear) because our civilization and technology protect us from the traditional forces of selection.

I don't see how that case can be made. I don't know how you could look at the world, or even our own country, and see a situation where there's no competition for mates or for resources.

I mean, last I checked, people weren't mating at random, but were making choices about who they chose to have children with; and 99% of the Earth's human population fails to enjoy the quality of medical care and attention that you refer to as supposedly "shielding" us from natural selection. I think the idea that natural selection has ceased its action on the human race is largely mythical. Even if there's a microscopic portion of human beings for whom historic environmental pressures have been eased - us - that's not the case for the majority of humans, and for every human, sexual selection is very much still in play. And even the environment of Western wealth and affluence comes with its own environmental pressures. I can probably find a few examples of beneficial mutations that are being selected for as defenses against the saturated fats and refined sugars in the Western diet.

Sure, the stuff I mentioned might not have a direct relationship to genetics. But if we're talking about the wholesale reduction of human genetic fitness in the past 6000 years, why are we so much smarter than the people who lived at that time? Why is it that we're the ones with the rocket ships and the Internet, and not them? Why is it that we're the ones for whom bubonic plague is just a weekend's worth of sniffles, and they're the ones for whom it was the harbinger of the apocalypse? (Hyperbole, BTW.)

Science fiction and fantasy give me a pretty good idea of what it looks like when a civilization degrades from a perfect state. Grunting savages worshipping in the shadows of machines that are slowly succumbing to entropy with no one smart enough to do simple maintenence. It's the world of Dungeons and Dragons campaigns; it's the world of Asimov's Foundation novels.

Doesn't really look like that, does it? Antiques are primitive, not god-like. Old computers are hilarious in the unsophistication of their design, not mysteries of ancient know-how that our modern engineer-preists guard jealously at the same time that they abandon hope of understanding them.

Ok, more hyperbole. But that's what I would expect it to look like, eventually, after millenia of decline. And it doesn't look like that. We're getting better, not worse.


This message is a reply to:
 Message 151 by Percy, posted 08-25-2006 12:18 PM Percy has replied

Replies to this message:
 Message 155 by Percy, posted 08-25-2006 2:05 PM crashfrog has replied

  
crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 156 of 223 (343367)
08-25-2006 2:36 PM
Reply to: Message 155 by Percy
08-25-2006 2:05 PM


Re: Trade-offs
Examples of such things are natural resistance to disease, eyesight, physical attributes (strength, speed, agility, coordination, size, height, bone-size, pelvis width (women only), etc.), and so forth.

We're probably about to careen off-topic, but I would just like to say that while these are things very often asserted to be "insulated" from natural selection, it's not immediately obvious to me that this is the case.

Just because someone has a physical trait that, in our modern times, they choose to improve with technology, that doesn't seem to immediately indicate to me that, in a time without technology, they would have been "selected against." Stories about some primitive four-eyes who "gets eaten by a tiger because he can't see as well" seem more like jokes than genuine speculations on evolutionary pressures.

I mean let's be serious. Tigers have been known to hit 50 MPH in a flat run and can leap over 10 meters. If you're close enough to a hidden tiger to see it, even with 20/20 vision, what possible advantage do you gain from that? And also - tigers don't live in Africa.

What I'm saying is, our technologies haven't nearly changed the pressures on us as completely as you seem to suggest. Somebody who uses glasses today might simply have asked his buddies "hey, do you see any mammoths over there?" back then and completely ameliorated the disadvantages of having 20/200 vision or whatever. People have been organized into cooperative communities for all of history and that's a "technology" that overcomes a lot of these physical variations right there.

The pelvis thing, though. You're probably right about that.


This message is a reply to:
 Message 155 by Percy, posted 08-25-2006 2:05 PM Percy has replied

Replies to this message:
 Message 157 by Percy, posted 08-25-2006 2:57 PM crashfrog has replied

  
crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 158 of 223 (343378)
08-25-2006 3:50 PM
Reply to: Message 157 by Percy
08-25-2006 2:57 PM


Re: Trade-offs
It's kind of a surprise that the same people who can argue that one light sensitive cell is better than none, and that two light sensitive cells is better than one, and so forth, can somehow deny that better vision confers a survival advantage.

If it was such an advantage that lacking it was a death sentence, why would there be such a range in visual acuity among humans? We've only had effective perscription eyewear for maybe 100-200 years now. That's an eyeblink, maybe 6-8 generations. Not nearly enough time for the great variation in human eyesight to be a function how perscription eyewear keeps us from being hit by buses at age 12 or something.

Look, I can imagine plenty of situations where sharp perception spells the difference between life and death. Just as the difference between standing here or standing there means the difference, occasionally, between being the guy that the rock crushes and being the guy that moves in on his girl after the funeral. I just can't imagine enough such situations that, in aggregate, they represent a serious selective pressure. Some amount of differential survival is always just random noise.

I'm sorry to harp this point, I really am. And it seems like there's only so much disagreeing you can do with Percy before it's all "how can someone so smart be so nuts?!" But everybody swings that old chestnut about how "we're so smart nowadays that we've conquered natural selection!" but it seems like nobody ever gives it much thought. And when you do think about it, it pretty much evaporates. Sure, life in a city is a different environment than life in the wilderness. But the idea that we're somehow weighed down by all these "weak" people we allow to survive is pretty ridiculous. Aren't they the strong ones, if they're so skilled at manipulating the rest of us into building a civilization designed for their benefit?


This message is a reply to:
 Message 157 by Percy, posted 08-25-2006 2:57 PM Percy has replied

Replies to this message:
 Message 160 by Percy, posted 08-25-2006 4:22 PM crashfrog has replied

  
crashfrog
Member (Idle past 698 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 182 of 223 (343427)
08-25-2006 8:54 PM
Reply to: Message 160 by Percy
08-25-2006 4:22 PM


Re: Trade-offs
Nothing you said counters the argument that civilization and modern medical technology insulate people from the types of selection pressures imposed on those living under primitive conditions.

Obviously it does, to the extent that the modern environment of medicine and technology is a different environment than the primitive world.

It doesn't follow from your conclusion, though, that no selective pressures emerge to take their place. Every environment has pressures. And in the face of those pressures I don't see any reason to take Faith's model of increasing genetic degeneracy seriously, and I don't see what reason you have to do so, either.


This message is a reply to:
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