A Beneficial Mutation

[Solomon Zorn]

I saw this report on CBS News the other day, and I thought of posting it.

Possibly a beneficial human mutation, found in a group of Amish, that's giving us insight into heart disease.

http://www.cbsnews.com/videos/preventing-heart-attacks-new-study-says-gene-mutation-can-ward-off-threat/

It got me to wondering just how often such positive mutations take place.

[Icarus]

I saw this report on CBS News the other day, and I thought of posting it.

Possibly a beneficial human mutation, found in a group of Amish, that's giving us insight into heart disease.

http://www.cbsnews.com/videos/preventing-heart-attacks-new-study-says-gene-mutation-can-ward-off-threat/

It got me to wondering just how often such positive mutations take place.

That's a hard one to calculate. Our polymerases have error rates when replicating our DNA, which creates mutations. The environment we live in is another cause of mutations, lots of possibilities that can vary greatly from region to region. In the case of the Amish and other secluded groups you have a lack of genetic variability causing mutations that are compounding over time due to limited genetic diversity being introduced into the gene pool.

Replication errors and mutations are happening all the time, but in the vast majority of cases it causes no change that can be measured over our lifetime (ie. completely harmless). Sometimes a single base pair mutation can be quite dramatic, Tay-Sachs disease for example (http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease). One base pair mutation on the HEXA gene and you could get a non-functioning protein that's critical to a functioning central nervous system. I don't know of any base pair mutations that are beneficial.

The best answer I can give is that beneficial and destructive mutations are happening all the time.

[Solomon Zorn]

Forgive me for being an uneducated hick, but is it possible that evolution on a macro scale takes a similar growth curve to an individual life form, going from the simple to the complex, until a maturity point is reached?

I would define a maturity point as when further changes become detrimental, simply by being random changes in something that has already become a complex system. Mutation would therefore no longer be as strong a positive force for change as it might once have been to a lower life form, because almost any random change, at this point, is going to be bad. Evolution of life on Earth must be taking some kind of predictable curve, and it seems to me that we are at a leveling off point for random genetic mutation.

The way I see it, human evolution is now external, taking an obvious form in how humans interact with with their environment through technological advances, and taking a more subtle path in the growth of human interaction with each other.

[Icarus]

Forgive me for being an uneducated hick, but is it possible that evolution on a macro scale takes a similar growth curve to an individual life form, going from the simple to the complex, until a maturity point is reached?

I would define a maturity point as when further changes become detrimental, simply by being random changes in something that has already become a complex system. Mutation would therefore no longer be as strong a positive force for change as it might once have been to a lower life form, because almost any change, at this point, is going to be bad.

Not really as that would imply evolution has a direction and an ultimate endpoint. Humans have to adapt to their environment, so there can't be an endpoint as the "perfect complex form" is an ever changing, unreachable, abstract thing. The great thing about mutations causing detrimental traits is that the trait usually prevents the person from reproducing, thus passing on the trait. Huntington's disease is a great example of a terrible genetic disease that can be passed on because it doesn't impact the individual until their late 30's. Most people have their children before then so the trait gets passed on.

Genetically, compared to plants, humans are boring and simple forms of life. If there is a "maturity point", and I don't think that's likely, we are far from it.

Evolution of life on Earth must be taking some kind of predictable curve, and it seems to me that we are at a leveling off point for random genetic mutation.

The way I see it, human evolution is now external, taking an obvious form in how humans interact with with their environment through technological advances, and taking a more subtle path in the growth of human interaction with each other.

You're going to have to elaborate your reasoning on this, I've not seen or read anything that suggests this is viable.

[Solomon Zorn]

Not really as that would imply evolution has a direction and an ultimate endpoint.

Not any kind of intentional endpoint am I suggesting, just a slowing down of the more rapid change that may have taken place in ages past. A relative leveling off. Perhaps most of the potentially beneficial mutations have already occurred, like developing limbs. Beneficial changes may have slowed down because the system is already so complex that only subtle changes can be beneficial.  I mean, how often do we see beneficial mutation occurring today in higher life forms? I think it's more frequent in simpler forms. To say it's predictable curve may be taking it too far.


But like I said, I'm an uneducated hick just tossing out an idea that's way above my pay grade. 

[stromboli]

Question; is this diet based or some other factor that could cause this? The Amish live a life centered around a very specific food supply and have done so for generations. So is the diet the driver or some other factor? I would think their lifestyle would tend to preclude heart attacks, being active people.

[Icarus]

Not any kind of intentional endpoint am I suggesting, just a slowing down of the more rapid change that may have taken place in ages past. A relative leveling off. Perhaps most of the potentially beneficial mutations have already occurred, like developing limbs. Beneficial changes may have slowed down because the system is already so complex that only subtle changes can be beneficial.  I mean, how often do we see beneficial mutation occurring today in higher life forms? I think it's more frequent in simpler forms. To say it's predictable curve may be taking it too far.


But like I said, I'm an uneducated hick just tossing out an idea. 

It is a slow process, the development of limbs in animals didn't happen overnight. It went through many stages of limb variation and many, many endpoints where different types of limbs didn't survive. The same changes are going on right now, but as with limbs, they're occurring very slowly.

The difference between "higher" and "lower" lifeforms is entirely subjective to the individual making the distinction. Again, if we are looking solely at genetics, humans are boring and simple organisms. If we look at neural complexity and the potential for abstract thinking, humans rank very high.

The typical beneficial mutations we see in "lower" lifeforms is antibiotic resistance in bacteria. This is occurring at a faster rate than in humans because the generation time in bacteria is incredibly small compared to humans. Bacteria can also transfer useful bits of genetic code between themselves so beneficial traits propagate quickly.

[Solomon Zorn]

Question; is this diet based or some other factor that could cause this? The Amish live a life centered around a very specific food supply and have done so for generations. So is the diet the driver or some other factor? I would think their lifestyle would tend to preclude heart attacks, being active people.

He says their triglycerides don't go up even when they drink a milkshake.

[Mermaid]

The Amish are a good group of people to study since the genetic diversity among the community is smaller--there are more recessive genes, and this kind of mutation will not be diluted as quickly as the general population. I am being polite here, but it's not uncommon for relatives to marry in the Amish communities. The Founder effect is documented, for instance, among them.

[Mermaid]

Question; is this diet based or some other factor that could cause this? The Amish live a life centered around a very specific food supply and have done so for generations. So is the diet the driver or some other factor? I would think their lifestyle would tend to preclude heart attacks, being active people.

The actual gene has been isolated. This is an actual target for drug therapy. Really interesting stuff.