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Evolution: the Facts.

Plutonic rocks: another name for intrusive rocks. So named after Pluto the Greek god of the underworld.
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Are you sure?

From somewhere in the dim recesses of my mind (perhaps dating back to the time I was drachmaless in Patras), I recalled something about wealth - something that Wikipedia confirms

http://en.wikipedia.org/wiki/Pluto_(mythology)
Pluto was originally the Roman god of certain metals and, because these materials are mined, he also took on the role of god of the underworld. The Greek word for wealth is Πλοῦτος (Plοutos) and it is believed that the Romans derived Pluto from the Greek because these metals, jewels and other riches lie under the Earth.
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Please pardon my presumptiousness and the pun... but to me the Rocks entry seems a tad light...

Yeah... I know... teh interwebs are at my finger tips... but... I'm lazy and I'd like to read/learn/know more in one hit - esp about the way specific types of rocks in various locations gave rise to the development of tools like adzes

And I'm curious to know whether or not and/or how some types of rocks are similar/different in various parts of the world - for example marble, something Italy is renowned for and something we here have in spades

http://en.wikipedia.org/wiki/Takaka_Hill
Takaka Hill is a range of hills located in the northwest of the South Island of New Zealand. Made of marble which has weathered into many strange forms and with numerous sink holes, it is typical karst country.
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http://en.wikipedia.org/wiki/Karst
Karst topography is a landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite. Due to subterranean drainage, there may be very limited surface water, even to the absence of all rivers and lakes. Many karst regions display distinctive surface features, with sinkholes or dolines being the most common. However, distinctive karst surface features may be completely absent where the soluble rock is mantled, such as by glacial debris, or confined by a superimposed non-soluble rock strata. Some karst regions include thousands of caves, even though evidence of caves that are big enough for human exploration is not a required characteristic of karst.
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six7s said:
This is fascinating... the next word is but...

But I'm now suddenly and impatiently curious to know WHY cooling times influence crystal sizes... if there's a simple explanation then please include it
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Crystal growth is a kinetic process. In order for a crystal to grow, molecules must be given a chance to diffuse to the crystal and orient themselves to attach to it.
If you cool slowly, you allow enough time for this to occur. If you cool rapidly, you do not give the molecules enough time to form the crystal.
 
In order for a crystal to grow, molecules must be given a chance to diffuse to the crystal and orient themselves
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Ahaaa! Bleedin' obvious to see - in hindsight...

Thank you
 
six7s said:
That repetition not only jars my eye, it doesn't tell me much that I couldn't have guessed
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I think in expository writing one should always sacrifice elegance on the altar of clarity.

Even if there was a synonym for sediment, I wouldn't use it --- you know how I feel about synonyms.

What are the influencing and/or prerequisite conditions?

I'm guessing density, pressure, temp (?), time (as in duration of being 'undisturbed by wind, tidal flows, etc)

I don't like guessing

Please help
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six7s said:
Please pardon my presumptiousness and the pun... but to me the Rocks entry seems a tad light...

Yeah... I know... teh interwebs are at my finger tips... but... I'm lazy and I'd like to read/learn/know more in one hit - esp about the way specific types of rocks in various locations gave rise to the development of tools like adzes

And I'm curious to know whether or not and/or how some types of rocks are similar/different in various parts of the world - for example marble, something Italy is renowned for and something we here have in spades

http://en.wikipedia.org/wiki/Takaka_Hill


http://en.wikipedia.org/wiki/Karst
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All this, and more, will be revealed in the promised separate articles on igneous, sedimentary, and metamorphic rocks. Watch this space.

six7s said:
Are you sure?

From somewhere in the dim recesses of my mind (perhaps dating back to the time I was drachmaless in Patras), I recalled something about wealth - something that Wikipedia confirms

http://en.wikipedia.org/wiki/Pluto_(mythology)
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Yes, "Pluton" means "the wealthy one", but the reason plutonic rocks are called plutonic rocks is because Pluto was also god of the underworld, and plutonic rocks form underground.

six7s said:
PS

You ROCK

;)
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Cheers.
 
Darkhole said:
Just when I thougt, .... get it.:confused:
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From what I've read (the article and other dicussions of it):

Transfer of genetic material amongst unicellular life might make it impossible to arrive at a conclusion of what sort of being the LUCA was. This has no effect on metazoan life, the overwhelming evidence is that we're monophyletic and thus would fit the tree.
 
Actually URS, it seems a little more complex than that:

Guardian article

Last year, scientists at the University of Texas at Arlington found a strange chunk of DNA in the genetic make-up of eight animals, including the mouse, rat and the African clawed frog. The same chunk is missing from chickens, elephants and humans, suggesting it must have become wedged into the genomes of some animals by crossbreeding.
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I am a little surprised by this statement, as I'd have thought that viral transfer would have been more plausible (c.f. the famous mariner gene)

But it is support for the (in retrospect) obvious contention that the templates (i.e. genes) are what evolve.
 
There is some really cool new data discussing one of the mechanisms on how some bacteria are able to develop antibiotic resistence.

It's actually based upon the bacteria decreasing it's DNA repair mechanisms, increasing the mutation error rate. This allows for a rapid genetic diversification from even a single bacterial colony.

The example speaks directly against the "No-harmful mutation" argument and shows how even repair mechanisms can be harmful in certain settings. This is a counter intuitive result and one that wouldn't at all be explained by a "non evolutionary" theory.

Do you think a page on this is useful in skeptic wiki? I can write it up this week.
 
joobz said:
There is some really cool new data discussing one of the mechanisms on how some bacteria are able to develop antibiotic resistence.

It's actually based upon the bacteria decreasing it's DNA repair mechanisms, increasing the mutation error rate. This allows for a rapid genetic diversification from even a single bacterial colony.
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It isn't clear from your account whether the mechanism is just:
(a) Bacteria which for genetic reasons have weaker repair mechanisms are more likely to have mutations, hence more likely to have a beneficial mutation, which will be selected for, which will drag the genes for weak repair mechanisms along with it.

Or the more interesting mechanism:

(b) The bacteria have a built-in switch which reduces the function of the repair mechanisms under the influence of environmental stress.

Either way it's quite interesting, but (b) would be very interesting.

The example speaks directly against the "No-harmful mutation" argument and shows how even repair mechanisms can be harmful in certain settings. This is a counter intuitive result and one that wouldn't at all be explained by a "non evolutionary" theory.

Do you think a page on this is useful in skeptic wiki? I can write it up this week.
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It does sound like a cool result. I would suggest that you add it to the page on [swiki]Beneficial Mutations[/swiki]: firstly because it seems to belong there; and secondly because if you google on beneficial mutations that page is one of the top ten google hits, whereas an individual page with a more specific title might attract less attention.
 
Dr Adequate said:
Or the more interesting mechanism:

(b) The bacteria have a built-in switch which reduces the function of the repair mechanisms under the influence of environmental stress.

Either way it's quite interesting, but (b) would be very interesting
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I saw an article in Scientific American last year that outlined mechanism (b). Unfortunately, I no longer remember in which issue, or what it was called.
 
Dr Adequate said:
It isn't clear from your account whether the mechanism is just:
(a) Bacteria which for genetic reasons have weaker repair mechanisms are more likely to have mutations, hence more likely to have a beneficial mutation, which will be selected for, which will drag the genes for weak repair mechanisms along with it.

Or the more interesting mechanism:

(b) The bacteria have a built-in switch which reduces the function of the repair mechanisms under the influence of environmental stress.

Either way it's quite interesting, but (b) would be very interesting.

It does sound like a cool result. I would suggest that you add it to the page on [swiki]Beneficial Mutations[/swiki]: firstly because it seems to belong there; and secondly because if you google on beneficial mutations that page is one of the top ten google hits, whereas an individual page with a more specific title might attract less attention.
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There is strong evidence for b, although I think the jury is still a bit out.

bacteria seem to inhibit their defenses against oxidative stress, which does a couple of things.
1.) causes direct dna damage, which certain repair mechansims result in mutation.
2.) the activation of the SOS pathway, which upregulates DNA replication mechanisms that are error prone.

There is evidence in another paper that they show how different repair mechanisms, when mutated or knocked out result in an increased diversification. I think data is still needed to show that indeed the bacteria will augment these oxidative repair mechanisms from accurate repairs to increased error rate repairs.


It seems that established biofilms will generate this oxidative stress to induce diversifcation. This mechanism, however, hasn't been isolated yet. Neither has the exact radical species at play (if there is just one).

What is most facinating to me about this whole thing is that oxidative stress has been one of the key mechanisms used by our innate immunity to kill off foriegn microbes. White blood cells initiates the "respritory burst" that creates large amounts of superoxide via NADPH oxidase that can kill the engulfed or nearby bacteria. However, superoxide also dismutates into hydrogen peroxide, which is a more stable and diffusible oxidant. As such, I bet any money that bacteria use this diffusing hydrogen peroxide as a distant signal for determining if they need to upregulate diveresity to increase population survivability.

I've recently written a grant that will study wether we can use this mechanism as a means of surpressing diversification in our attempts at developing next generation antibiotic therapies.


ETA: I will attempt to edit the page this evening with proper references. I'll alert you when I'm done. I'm sure you've noticed that I am require many proofreaders.
 
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