Prions evolve

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Prions evolve

This is very cool. It turns out that prions evolve. Prions are not composed of DNA or RNA. They are simply proteins. Often they are similar to proteins found in living creatures, like us. They cause the similar proteins to "fold" in a way that makes the similar proteins just like the prions, thereby replicating the prion. These mis-folded proteins then lose their original functionality. The prions form long polymers, destroying cells in the process. This is the cause of bovine spongiform encephalopathy (mad cow disease), and the human equivalent, Creutzfeldt-Jakob disease. It's also responsible for a very rare, inheritable disease which causes the inability to sleep, leading to madness and then death.

This pretty much confirms (yet again) that evolution through mutability and natural selection not only works, but works in any system in which information is replicated and to which a selection filter is applied.

Why do I suspect there will still be folks who deny the process works, pretty much as Darwin said it did? Here's something that doesn't have even RNA, let alone DNA, performing in a way predicted by Darwin 150 years ago. Yet I think there will be many who will ignore this new (and extremely interesting) data.

Anyway, the article is interesting. Enjoy.

"Yes, I seriously believe that consciousness is a product of a natural process. I find that the neuroscientists, psychologists, and philosophers who proceed from that premise are the ones who are actually making useful contributions to our understanding of the mind." - PZ Myers

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I read this, but I think the

I read this, but I think the researcher overstates the case. The prions adapted, they didn't evolve. They are the exact same proteins, just folded somewhat differently. The missing element is variation/mutation.

These prions found an optimal way of folding based on their surrounding environment, but no new variations of the prions were created. To say that these prions evolved would be to say that ice crystals evolve when they find optimal ways of forming snowflakes in various atmospheric conditions. Sometimes you get big fluffy puff balls. Sometimes you get tiny icy pellets, sometimes you get sharp hexagonal flakes. It all depends on the atmospheric conditions and the crystallization properties of water, but you're not ever going to get regular pentagonal snowflakes or octagonal ones, and you're not going to get any snowflakes that can withstand greater than 0 degrees celsius. You won't find snowflakes adapting to the weather in the Bahamas, for instance.

Prions are strangely folded proteins that interact with *existing* proteins and cause them to also fold into strange shapes. Some strange folds are more likely to cause other proteins to take on the same strange folding. However, you will never get a *new* protein suddenly appearing. The folding is more akin to snowflake crystallization -- where ice crystals interact with existing water molecules to create a particular shape of snowflake -- than it is to actual DNA evolution, where the actual information encoded in the DNA can mutate and those mutations can subsequently be inherited. You'll never find a prion evolving into a different protein.

It's also similar to epi-genetics, where gene (de)activation sites are passed from one cell to its daughter cells. The actual DNA code has not changed, so the 'evolution' is not permanent, it's just a phenotypic adaptation, not true evolution. Reset the cell's markers and you get the original genome back.

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 I think this phenomenon is

 I think this phenomenon is illustrative of a basic rule of thumb regarding processes.  That is, if we are looking at a process which has been continuing while the environment changes, we shouldn't be surprised if there is flexibility in the process.

If I start at 1 with the process, "If X is a single digit number, add 1," I will reach ten, and the process will end, never to begin again.  However, if I start at one with "If X is a single digit number, add 1, and if X is more than single digits, add 1 to the far right digit, and if the far right digit is 0 while X is a multi-digit number, increase the next number to the left by one... etc, etc..."

Anyway... you get the point.  Adaptation is just a necessary component of processes that continue while the environment changes.  It probably seems really astonishing to a lot of theists, but that's because they haven't wrapped their brains around the elegance of complexity arising from simplicity.

With life, it's all about carbon.  Carbon is uniquely flexible in its ability to bond with other molecules, and the sheer number of possibilities makes it surprisingly... um... err.... unsurprising.... (ahem)... that organic molecules tend to get involved in complex chemical processes that have the ability to adapt.



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