Evolution and Creation an Honest Question

[Meffy]

Don: Just so. Someone correct me if I'm wrong, but it seems to me that an "advantageous mutation" is one which allows the recipient to live long enough to pass its genetic heritage on to offspring. Discomfort, unpleasantness of life, even low health level (short of failure to survive to breeding age) don't enter into the evolutionary process. It's about staying alive long enough to breed.

IOW, this kind of "advantage" is defined not in terms of the pain caused to a person who suffers from sickle cell anemia, it's defined in terms of that person living at least until he or she has reproduced.

Individuals are pawns. The species is the game.

 

[Roboramma]

Don: Just so. Someone correct me if I'm wrong, but it seems to me that an "advantageous mutation" is one which allows the recipient to live long enough to pass its genetic heritage on to offspring. Discomfort, unpleasantness of life, even low health level (short of failure to survive to breeding age) don't enter into the evolutionary process. It's about staying alive long enough to breed.

Basically, but you're missing out some things - like helping the chances of your offspring to reproduce itself (ie. parenting), helping the chances of your kin to reproduce, being able to find someone to reproduce with, especially when there are plenty of others trying reproduce as well.

I'm sure you know all this, just thought it bore pointing out. Evolution is about much more than survival.

 

[aggle-rithm]

Discomfort, unpleasantness of life, even low health level (short of failure to survive to breeding age) don't enter into the evolutionary process. It's about staying alive long enough to breed.

For some species, I think these things are important. A predator, for instance, needs to be at the top of its game to survive. That means being healthy and motivated for much of its life.

 

[aggle-rithm]

What makes some of this tricky is that we have a tendency to impose a human perspective on a blind, undirected process, without even realizing we are doing so. A notion such as "helping the species survive over the long haul" is a good example of this sort of hidden assumption.

I think this is a major reason that Creationists have difficulty understanding evolution. They aren't capable of viewing the issue from a purely mechanistic perspective.

I remember one classic quote from a fundie: "How does a bacteria know it's supposed to turn into a tree?"

 

[aggle-rithm]

The mutation originated in Africa and is believed to have spread through the population because of the malaria protection effect.

I've heard that the mutation developed independently in four or five different populations in Africa and Mesopotamia -- which would pretty much prove that it is advantageous. Anyone know more about this?

 

[UrsulaV]

thats inevitably pointed out is the question of the long haul. Its true that in the short term it can allow that person to outsurvive another against malaria. In the long run though it doesn't help the species surivve. For a good example of a beneficial mutation some thing clear cut and proven is a better choice then a disease that will save a person one day and endanger his life the next.

The long haul doesn't enter into it.

As people have already pointed out, evolution is entirely blind. Sickle cell is incredibly advantageous in a malaria ridden area, because if you have one gene, you're malaria-resistant. Therefore, you live, and breed, and some of your offspring survive. This beats dying without kids in an evolutionary sense every time.

You're also not neccessarily correct about sickle cell helping the species survive over the long-haul, although again, evolution is blind and this is pure chance. Consider:

Person A has one gene for sickle cell anemia. Worst case, they breed with a person with one gene for sickle cell. Malaria sweeps the town. Both A and their mate live, and have four children. One child dies of sickle cell (having inherited both genes.) One child dies of malaria (having inherited no genes.) A and their mate therefore have two surviving offspring, who are both malaria resistant. A's children each have four offspring of their own, again by malaria resistant mates, and again two die and two live. A therefore gets four grandkids. Each of those marry, have kids, half live, and A gets eight great-grandkids.

Person B has no genes for sickle cell, gets malaria, and dies a virgin.

The notion that sickle cell isn't advantageous is too...for lack of a better term, sentimental. We assume that one kid in four being likely to die is such a bad thing that this cannot possibly be a beneficial mutation. But in fact, malaria is so detrimental without modern medicine, and kills so many people that the increased ability to reproduce is actually a significant advantage. It doesn't matter if you lose the occasional kid--at least you're alive to have the kids to lose! If you're half-dead of malaria, even if you manage to have kids, they're not gonna be as healthy or as well-cared for as if you're resistant.

Even in a species sense, therefore, sickle-cell is a beneficial trait as long as you can't control malaria.

It's only now that we can control malaria that the tables are turned.

 

[MRC_Hans]

Back to the original question about advantageous mutations:

The idea that mutations are mostly disavantageous comes mostly from experiments with fruit flies.

Now, the many experiments with fruit flies (Drosphilia) were not made in order to make a better fruit fly. They were made to map the genes (the fruit fly is ideal for this because it is easy and quick to breed and has only four chromosomes).

Since the fruit fly is already excellently adapted to be ... a fruit fly, it is actually not very likely that anybody should succeed in making it any better; if such a mutation was possible, it would already have happened in nature. However, some of the mutations recorded, might have been advantageous if the fruit fly was under pressure to adapt to another lifestyle: Color changes, size changes, and the like.

Now, this is the central point: You cannot take an excellently adapted species and expect any mutation to make it better. What you CAN do is take a species under pressure to adapt to a new environment and look at mutations, and then you will find that mutations that might otherwise be a disavantage is suddenly an advantage. A couple of examples:

Fish in dark caves with degenerated eyes don't use energy on a vulnerable and useless organ.

Badgers and other cave-dwelling animals have advantage of short legs, which would have been a deadly disadvantage if they were to live in the open.

Penguins have lost the ability to fly, because in their environment all the food is underwater, so swimming is better.

Of course you might say that we don't know for sure that the above came by through mutations, so let me add one more:

Penicillin: Penicillin was vastly improved by expsing it to ultraviolet light, where it mutated and produced more active substance. That would probably have been a disadvantage in the wild (too high metabolic cost), but as a domistic life-form, it was a great advantage.

Hans

 

[delphi_ote]

Answers in Genesis and others stepping up attempts to misinform (billboard links to site that links to Answers in Genesis as "link to scientists"
http://www2.ljworld.com/photos/2006/mar/23/77309/

[qimg]http://media.lawrence.com/img/photos/2006/03/23/billboard.jpg[/qimg]

http://www.scienceprovesit.com/

Nothing can gain entropy! It's a physical law! Oh snap! They just proved it with science.

I guess someone better tell all those photosynthesizing plants to knock it off before the physics police come and arrest them.

 

[pjh]

Even dog breeds (all decendents of wolves and still the same species in that they can breed and produce viable offspring) show beneficial mutations (at least that which humans find beneficial...)

Here's something I've never clearly understood. Are the differences we see today in dog breeds the result of
- mutatations
- Recombination of traits present in wolves by sexual reproduction.

Is it some complex interaction of the 2? When we see the difference between a pekinese and a great Dane, are these mutations or the selection of characteristics/genes present in wolf genes, but recombined.

Let's say I start beeding dogs for hairlessness, and after x generations I have a hairfree dog, would each step in that process be classified as a mutation (in the context we're taking about here - beneficial mututaions)?

 

[Bronze Dog]

Somewhere on Pharyngula, a commenter mentioned one hypothesis of evolution where things speed up in isolation: One species of a fairly general phenotype generates lots of recessive mutations that don't show up in the phenotype. Part of the species gets isolated from the rest. Inbreeding begins. Recessive genes and their traits become more commonplace. Lots of new traits appear: "Good" ones persist, "bad" ones go back into recessiveness.

Don't know how accepted that hypothesis is, but it sounds like a pretty reasonable scenario to me.

Would make sense for dogs, since breeders essentially isolate different populations.

 

[MRC_Hans]

Here's something I've never clearly understood. Are the differences we see today in dog breeds the result of
- mutatations
- Recombination of traits present in wolves by sexual reproduction.

They are both. Some differences are due to selective breeding of certain traits that were there all along, others are mutations. For instance, the short legs of the Basset Hound are, AFAIK, due to a mutation.

Is it some complex interaction of the 2? When we see the difference between a pekinese and a great Dane, are these mutations or the selection of characteristics/genes present in wolf genes, but recombined.

Don't know if that particular one involves mutations or not.

Let's say I start beeding dogs for hairlessness, and after x generations I have a hairfree dog, would each step in that process be classified as a mutation (in the context we're taking about here - beneficial mututaions)?

It seems that the ability to evolve a hairless variation is inherent in most species, so that is probably just a recessive genetic disposition that can be selected for.

Basically, however, ALL genetic traits originate from mutations, although many mutations have no obvious effect on individuals. They just change the overall possibilities in a given gene-pool.

Hans

 

[blutoski]

Hey I'm personally a christian who believes in evolution. One question I've often heard though I don't know a good answer for. Simply put a lot of creationists say that there is no known examples of a beneficial mutation. Can any one give me an example? I"m not saying it proves or disproves any thing but its a good question.

Tay-Sachs is about twenty independent, recent, mutations that provide exactly the same thing: heterozygous carriers have resistance to tuberculosis.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed


Another much more recent one is the <i>Milano allele</i> which was a <i>de novo</i> about two generations ago, and provides some protection from cholesterol damage to arteries.

http://www.ncbi.nlm.nih.gov/entrez/...t_uids=8473493&query_hl=5&itool=pubmed_docsum

 

[blutoski]

Here's something I've never clearly understood. Are the differences we see today in dog breeds the result of
- mutatations
- Recombination of traits present in wolves by sexual reproduction.

Is it some complex interaction of the 2? When we see the difference between a pekinese and a great Dane, are these mutations or the selection of characteristics/genes present in wolf genes, but recombined.

It's a combination of the two. Canus has a lot of alleles per gene, so there's plenty of opportunity for recombination variety. More so than Homo, apparently. Very malleable species.

Also: I don't think the model is that dogs are descended from wolves, so much as they probably have a very recent common ancestor, and are therefore inter-breedable.

Let's say I start beeding dogs for hairlessness, and after x generations I have a hairfree dog, would each step in that process be classified as a mutation (in the context we're taking about here - beneficial mututaions)?

You wouldn't know if it was a mutation or recombination that produced the new trait unless you knew which genes were responsible, and knew the alleles of the participants. New alleles would be evidence of mutations.

 

[SpaceFluffer]

I remember one classic quote from a fundie: "How does a bacteria know it's supposed to turn into a tree?"

Reminds me of a joke:

An engineer, a mathematician and a mystic are discussing the most important inventions in the history of mankind.

The engineer chooses the wheel as the most important, because it gave mankind the power to travel great distances and transport objects around.

The mathematician chooses calculus, because it gave mankind the ability to truly understand the mathematics of the natural world, and quantitatively describe the universe in the language of math.

The mystic chooses the Thermos flask. When asked why, he says "Think about it. When the liquid is hot, it stays hot. When the liquid is cold, the flask keeps it cold. That little flask - how does it know?"

 

[Dymanic]

Here's something I've never clearly understood. Are the differences we see today in dog breeds the result of
- mutatations
- Recombination of traits present in wolves by sexual reproduction.

The genetic distance between wolves and domestic dogs is negligible, evidenced by their being fully fertile on crossing. The differences we see at the level of phenotypes is due mostly to selection (artificial in this case) operating on that variation (provided by mutation) which exists in the wolf genome.

 

[Meffy]

Basically, but you're missing out some things - like helping the chances of your offspring to reproduce itself (ie. parenting), helping the chances of your kin to reproduce, being able to find someone to reproduce with, especially when there are plenty of others trying reproduce as well.

I'm sure you know all this, just thought it bore pointing out. Evolution is about much more than survival.

True, and [awful sentence alert, sorry] I can see that if extreme enough, some mutations that benefit the species biologically while being unpleasant for individuals might affect them enough to make them less effective at, for instance, parenting or other activities valuable to survival.

Funny thing: I'm thinking of Yenta in "Fiddler on the Roof"... =^_^=

 

[bpesta22]

What about them misquitos in the london subway

When built 100 years ago, some misquitos were trapped underground-- for the first time ever.

They adapted by feeding on rats blood-- versus human or other animal blood.

100 years later, the misquitos underground cannot breed with those above ground (even though 100 years ago, they were in that same population of misquitos). So, they are a different / new species.

Not sure if this was due to a mutation, but it seems strong evidence of what a fundie would call Macro evolution.

Also, I thought the gene was the unit of selection; not the person and not the species.

Is this wrong?

 

[Meffy]

I'm no doubt using language imprecisely. I've no chance at the English award.

 

[supercorgi]

They are both. Some differences are due to selective breeding of certain traits that were there all along, others are mutations. For instance, the short legs of the Basset Hound are, AFAIK, due to a mutation.

You're right. All the short-legged (in proportion to their body size) dogs like the Basset Hound (and my own SuperCorgi) are achondroplastic and carry the gene mutation that causes dwarfism. This mutation is also known to appear spontaneously in felines and since the 1980's a "new" breed of cat has been introduced called the Munchkin who are all descended from a single short-legged female feral cat found in the US.

 

[pjh]

So here we have mutations (survivable) causing short legs, and we can all think of environments where short legs might be an advantage so is it not 'case closed'? here's a mututation (see the piccy!) if it lived in tunnels it would be beneficial so please go away and invent some other silly challenge to evolution.

The other important thing here (for me anyway) is that a lot of variation can be created just by sexual reproduction, hence no need for mutations to cause some fairly dramatic body/behaviour differences for Natutal Selection to act on.