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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."
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.
Not really related, but it is entirely possible for humans to be "alive" in a physical sense even after they are brain dead. As long as they are hooked up to respirators etc., they can be kept alive indefinitely. To date, no human being is ever known to have regained consciousness after brain death.
The _big_ catch here is that most physicians are not properly trained to test for brain death. Most physicians will just see a flat line on an EKG and declare the patient brain dead. I used to work at an organ transplant center, where there were technicians that went through a formal checklist to make sure the patient really is brain dead. It was not uncommon to find patients who did not meet the strict criteria. In the most dramatic example, a 3-yo boy was supposedly brain dead, and he was in the operating room, ready to have his organs removed. The technicians discovered that his pupils did respond to light, so they rushed him out of the OR. On the way back to his room, the boy opened his eyes and smiled. But then he went back into a coma and died 5 days later.
Needless to say, the boy's parents were furious.
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.
Putting the perils of terming new knowledge "obvious" aside, it does seem obvious that evolutionary mechanisms would have to be preexisting for life to have indeed evolved. Since the most generic definitions of life I've seen boil down to providing some form of localized reverse entropy, evolution of the materials of that reverse entropy should be able to happen before the condition itself is actually achieved.
To draw an utterly meaningless comparison, you can certainly have a power supply without a computer, but good luck doing any computing without the power supply. If that makes sense. I should probably cut my breakfast rum down to under 5 shots.
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.
All things in the Universe try to minimise the amount of energy they have. In some special cases, like crystals for example, this means becoming more ordered: the energy of each atom/molecule depends on its distance from its neighbours, with each "preferring" the lowest energy distance. Getting as many neighbours as possible at this distance is effectively packing spheres with that distance as their radius, which turns out to be the most efficient with ordered arrangements like hexagonal close packing, so that's what's observed. In the general case, however, the amount of order goes down, see http://en.wikipedia.org/wiki/Entropy . In fact, in every situation which becomes more ordered over time, Thermodynamics says that somewhere else there must be a system becoming even more disordered (as an example, if a system is minimising its energy by becoming ordered then it's exothermic: the energy its losing will come out as heat. This heat is itself disordered, and can disrupt the order of whatever it comes into contact with (which is why so many Physics experiments are done as close to zero Kelvin as possible). Also, the total energy such systems manage to lose is restricted by the fact that they are becoming more ordered, there is an "entropic cost" when becoming more ordered, which means that it requires energy to do and therefore the system must keep hold of that much energy to do it.
For a simple example of how becoming more ordered takes energy, try stretching an elastic band. The polymers it's made of would, in a totally disordered system, take "random walks", which is very degenerate (there are LOADS of ways to randomly walk a certain distance starting at a point A and ending at a point B is the distance AB is much shorter than the distance you walk, ideally A and B are in the same place). That's the band's preferred state, and as such it isn't particularly long. By stretching it, the distance AB goes up, so there are fewer random walks of the same length which satisfy these new positions. In the extreme case the distance AB will be the same length as the walk, and there would only be one valid random walk between them (ie. going in a straight line). It takes energy to stretch the band because you're making it more ordered, which it doesn't want to be.
If matter's mission is to find greater order then a stretched elastic band would never snap back ;)