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Prions Evolve Despite Having No DNA
An anonymous reader writes "Scientists from the Scripps Research Institute have shown for the first time that 'lifeless' organic substances with no genetic material — prions similar to those believed responsible for Mad Cow disease and similar, rare conditions in humans — are capable of evolving just like higher forms of life. The discovery could reshape the definition of life and have revolutionary impacts on how certain diseases are treated."
Genetic material and DNA aren't really synonymous, are they? Alien life that appeared independently of that on Earth would likely have "genetic material" that served a similar purpose to DNA, but wasn't DNA.
Prions are proteins that, like viruses, replicate via a host cell. All the high-level principles of evolution by natural selection apply; it's just the low-level mechanisms that are quite different.
That must be how the Crystalline Entity came into being.
Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
Natural selection doesn't pre-suppose DNA. Anything which multiplies to produce copies of itself, which can degrade/mutate between generations can evolve just in exactly the same way. Selection pressures work exactly the same. So does the chain reaction effect of multiplication of the survivors, resulting in major shifts in characteristics of a population.
But the actual story is the bad news part of it. That using anti-prion medication probably won't work all the time as it would just breed a drug-resistant breed of prions by preference.
Definitely bad news. We can forget about having the "saviour" take a bath in the daily oatmeal for our protection :)
Quidquid latine dictum sit, altum videtur
It's time we recognized that the interesting things about "life" are all just products of the fact that all kinds of systems can convey self-replicating entities of some sort, and they tend to be interesting and undergo evolutionary processes and etc. Whether they are non-biological DNA bundles, cellular organisms, oddly folded proteins, crystalized clay, etc.
So where are the nefarious / useful engineered prions at?
It's a little more complicated than that. There's basically three properties that are both necessary and sufficient for evolution to take place.
* Some sort of fitness function
* Reproduction, largely based on the properties of the "parent"
* Imperfect reproduction, so that variation can be introduced
Once you've got those three items, you have the potential for evolution.
That said, it should be pretty obvious that basically any frequently-duplicated structure in the physical world, whether it be made out of DNA, protein, or metal and gears, is going to have all three of those items - the third just thanks to the physical world being imperfect. Note that it's not required that it be capable of duplicating itself - if all machines were built by copying older machines, we'd get to see "machine evolution" as people tended to copy the ones that worked better and throw away the ones that didn't.
Of course it's also worth pointing out that none of these requires that the item exist in a physical sense - you can meaningfully talk about memetic evolution, societal evolution, language evolution, joke and humor evolution, so forth ad nauseum.
Breaking Into the Industry - A development log about starting a game studio.
Rocks evolve too.
Hasn't this bullshit "claim" been dredged up enough already? It's just a bit of really weak sensationalism from an attention-whoring geologist.
He himself doesn't even believe this nonsense, and does say, towards the end of that article that obviously "being changed by your environment" has nothing to do with "evolution", but hey, why not get some free publicity?
sic transit gloria mundi
No flames can kill prions.
This is misleading, and upon second reading, it is some overly-philosophical hand-waving.
Yes, prions do not reproduce through the conventional genetic mechanisms. From my understanding, they encourage, through some direct protein-protein interaction, other polypeptides to fold incorrectly.
Think of it this way. HIV and other genetic disorders propagate through normal reproductive means. Like, if a person with an extraordinary innate musical ability has a child, that child will probably possess a natural ability for music.
However, if a talented musician adopts a child and then teaches him how to read music and how to play instruments, he will probably grow up to be equally talented.
Prions are similar to the latter case. They are encouraging other proteins, who don't in themselves possess any malicious function, the fold in such a way to attack the host.
This isn't reproduction. The "parent" prions are not in anyway responsible for the actual formation of the "child" prions. They are just responsible for causing them to become malicious, making them more role-model proteins than actual parents.
it's late, i'm over tired and maybe i should have cooked that last brain i ate. anyway i did a reread of Darwin's TOOS and then binged on a buncha evolutionary theory and evo-devo stuff, this over the last 3 years. 1st off evolution theory, at least the mainstream stuff presupposes a genotype (dna) translated into a phenotype like me typing this. so the question should arise as to whether prions have a genotype source that has a transcription mechanism. old school Darwinianism as penned by Darwin drifted toward acquired characteristics a la Lamarck because Darwin didn't have any working knowledge of genetics even tho Mendel had sent him a draft of his work. somewhere over 95% of all species have gone extinct and after all the reading and questions i came away seeing life as a random walk of living crud crusting eons of dead crud. no winners no losers no game no gameplan just stuff that hasn't died yet on top of stuff that has; being slow cooked by a middle aged average sun.
ideopath @ play
Shame I don't have any mod points right now. That comic strip is quite funny and more on topic than off.
I'm not quite sure I would call it evolution. I can easily imagine that many prions replicate not only themselves but variations as well and those variations will produce variations of different proportions and so on and so forth. So just because you subjected a prion to an adverse environment for a particular copy of a prion only means that form will be less populous.
It feels to me that this is less evolution and something more akin to chemical computation. Although ironically it does in some ways remind me of the poorly labeled Conway's game of life.
Any matter has one mission and one mission only: to find greater order. If matter without DNA or any prior form of order couldn't achieve more order, then life would not exist. Things want to be able to interact with their environment more efficiently, and must evolve to do so.
As posts above testify, the word "evolution" is used more and more in contexts that have nothing to do with life.
For example people talk a lot about the evolution of ideas, societies, and so on... Quite possibly, the philosopher Wilson is one of the popularizers of this approach.
Anyway, this also leads to a different point - Evolution by itself is not a proof of the existence of Life. For example, Ideas or Societies are not living organisms, yet they do evolve.
So the fact that prions evolve does not mean they are alive! One can fairly say that they are just a chemical (a protein) that can reproduce itself, evolve, and do damage.
In Science, Mathematics and Philosophy, it is very common to take "edge cases" in order to better understand the limits of an idea. Prions give us a good example of something that can reproduce and evolve, yet its a chemical not a living organism.
So what is "Life" ? Perhaps we should require the ability to perceive - awareness of ones surroundings - in order to define true life? In that case Bacteria aren't alive either, which is fine by me.
Jellyfish and Lizards do qualify as alive. More generally, you would need some sort of functioning nervous system (however primitive) to be "alive". Brain-dead people would possibly not be "alive" by this definition.
But you’re no better. You insult the other side, and bring no arguments to the table. You’re obviously right... to us... but to them, you now just made it worse, making them protect themselves from your pointless attacks even more.
This time, I’ll do it for you:
The difference is, that Rocks have no fitness function. Which is the difference between undirected change and directed evolution.
But the next time, if you wanna act superior, bring an argument. Like a common basis, and proper logic on top of it.
Any sufficiently advanced intelligence is indistinguishable from stupidity.
that but not by much. Basically they'll say little changes like that (they call it micro-evolution) can happen but nope, no big ones into other species. (But anybody that's taken Bio 102 and seen how impossible it is to come up with a definitive answer to what is one species is and what is another knows that differential is horse-shit.) Guess they needed that so they could have an excuse why it was ok to take newer antibiotics and such. (You know, so they could allow the evolution that's so obvious you have to be pretty much insane to say it doesn't happen.)
Did you know 80 to 90% of the moderators on slashdot wouldn't recognize a troll even if one dragged them under a bridge.
It ate all of the Not-So Grand Canyons?
If I have been able to see further than others, it is because I bought a pair of binoculars.
That's not the interesting part of this. First of all, prions were never consider life. They are not even nearly as complex as viruses, and no one really thought there was any kind of hereditary mechanism in what amounts to a relatively simple protein structure.
What it does tell us is that where there is replication, there will be adaptive and evolutionary processes.
The world's burning. Moped Jesus spotted on I50. Details at 11.
No, this isn't what I mean. The vast majority of devices are built by understanding the concepts involved and designing a new machine off those concepts. If we, instead, just measured a machine that already existed, then built another one to those approximate specs, over and over again, you'd see designs that were slightly "better" flourishing while designs that were slightly "worse" dying out. Thus, evolution.
Breaking Into the Industry - A development log about starting a game studio.
But that's exactly my point. It doesn't matter how the formation occurs. If the "parent" can reproduce, in any way, from construction to repurposing to just hanging around the "child" until the child starts acting like the parent, then it counts as reproducing. It's not like I have memes sitting in my head getting pregnant - their "reproduction" is that I say something funny to someone, and he remembers it, and says it to someone else.
Evolution is in no way restricted to lifeforms that can self-reproduce. Prions have a way to duplicate their important properties - their bizarre folding - and that's all that's necessary.
(And yes, role models can be a form of reproduction.)
Breaking Into the Industry - A development log about starting a game studio.
I didn't understand how they could be surprised that prions evolve, so I checked with the original article. They weren't. They were interested in the rates of evolution and the persistence of strains that were selected against. Quite reasonable.
Even totally inorganic matter evolves, in a rough sense. At it's basis evolution just asserts that those forms which are most suited to an environment tend to persist in that environment. This seems quite hard to challenge. Then it accepts Malthus computations on population, and asks: Given that it's obvious that not all descendants can survive, what does the two laws in combination imply?
N.B.: Darwin didn't know ANYTHING about DNA. Genetics hadn't yet been recognized. (This was after Mendel, but long before he was discovered.) So the basis of evolution clearly CAN'T depend on those facts. Evolution is really quite simple, it's just the working out of the details that is complex. (Just as Boolean logic is quite simple, but it's a long and complex way from Boole to a compiled program written in C.)
I think we've pushed this "anyone can grow up to be president" thing too far.