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Why Scientists Think Completely Unclassifiable and Undiscovered Life Forms Exist
An anonymous reader writes: In a new paper published in Science, researchers at the Department of Energy's Joint Genome Institute note that "there are reasons to believe that current approaches [to discovering life] may indeed miss taxa, particularly if they are very different from those that have so far been characterized." They believe life forms exist that don't fall into the established eukaryota, archaea, or bacteria kingdoms. They argue that there may be life out there that doesn't use the four DNA and RNA bases that we're used to; there may be life out there that has evolved completely separately from everything that we have ever known to exist; there may be life that lives in places we haven't even looked.
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To think that we have discovered all there is to know regarding life forms would mean that we already know all there is to know in this field.
So maybe we need to use different methods than the ones we have been using. Makes sense to me.
I was under the impression that news was about you know, new things. This is just an article highlighting that money has up until now been targetted toward things we are pretty sure exist. you know, novel creatures not using radically different genetic bases. This is just some dudes going, "yup, there might be more out there than we thought" which is you know, the basic premise of all the sciences.
Come back to me when they actually find something that uses a sixth nucleotide.
Incidentally, where might this new life have hidden, that we haven't searched already. We've got extremophiles in the middle of godforsaken rocks already... there aren't that many new places that i imagine we
A. haven't looked already
B. aren't already colonized by the cousins we know.
Generally speaking, the new life would need to be able to outcompete, in certain circumstances, the stuff we know or it wouldn't survive too well the 2 billion years that bacteria have dominated the planet.
i'd think the only viable thing would be viruses, maybe, and us not fully understanding them. but then i'd imagine if an different nucleotide were somehow incorporated into a virus we'd already found, it'd also be present enough to show up as an unknown nucleotide. Might not know what it was, but we'd most likely have an idea that it were there.
"It is not life as we know or understand it. Yet it is obviously alive, it exists"
--Spock, "Operation -- Annihilate!"
Welcome to the Panopticon. Used to be a prison, now it's your home.
I'd hardly be surprised if there were many forms of life that co-existed in the RNA world days, and eventually they just lost out to RNA and then DNA because maybe it is more efficient at replication.
There are thousands of stable molecules, some we have even made, that can support a similar system of structure like DNA and can be made fairly easily with low energies.
We know even DNA can replace a phosphor base with a more energetic arsenic and still function, more or less.
Most likely there were more energetic forms of life that could survive back in the hotter early days that died off as Earth cooled.
Maybe we will find that some planets that are really hot do in fact have some form of life, give at least some liquid is present that can be used for transfer and energy. (like water)
Hell, we may even find them as we dig deeper in to Earth and find caverns even deeper than the ones we have found so far with ancient life in them.
Let's just hope we don't find no temples.
What there likely isn't, though, is nuclear creatures living on the surface of stars.
Historically, "Life" has been defined as being any phenomenon that possesses all 5 life processes:
#1 Food intake/ nutrition
#2 Respiration
#3 Excretion
#4 Growth & Repair
#5 Reproduction
However, this seems to have been expanded to 7:
#1 Movement
#2 Respiration
#3 Sensitivity
#4 Growth
#5 Excretion
#6 Reproduction
#7 Nutrition
This is for "Life" in the generalized sense, fully abstracted away from any specific mechanisms by which those processes may be achieved. It is perfectly sensible for an artificial lifeform to be constructed, as long as it is able to fully carry out those processes. It needn't have any organic components whatsoever.
Nowhere in the historical definition of "life" used by life science is there a requirement for specific mechanisms-- just processes.
Massive generalization has been good to the sciences.
In physics, we have used invariance principles to expand our definitions to the most general possible. This was the argument behind General Relativity, for example: Einstein wanted equations of motion that would be invariant under any smooth second-order transformation whatsoever, and when he put that constraint, and only that constraint on, he found the most general form of the equations of motion were uniquely determined (up to a constant of integration, which is the Cosmological Constant).
Biologists have generally shied away from this kind of approach to their field, but there is an argument to be made that there is an equally general definition of "life" as "anything that participates in a process of evolution by imperfectly heritable traits that result in differential reproductive success". It need not be tied to any particular concrete mechanisms like DNA and RNA.
This idea may turn out to be silly (which is why I wrote a novel about it rather than a scientific paper: http://www.amazon.com/Darwins-...) but well into the 1800's there was no general view of "energy" that unified all the disparate forms, to the extent that the fact that light had energy that was in any way related to mechanical energy was not really appreciated. The kind of unified view of energy we have today would have seemed bizarrely speculative at that time, in the same way that the notion of a unified, generalized view of life is purely speculative today, but it turned out to be amazingly useful, so it's worth considering the possibility in biology today (anti-science people will likely attack it as a waste of money, using computer technology that would not exist without a similar "waste" on ridiculous fantasies like quantum theory and "obviously useless" research into the basic physics of semi-conductors in the past.)
Blasphemy is a human right. Blasphemophobia kills.
A self-reproducing system that does so perfectly, with no errors won't ever change, and isn't really alive.
If it is successful at surviving, why would it need to adapt to be alive ? Maybe it's already perfectly adapted to its environment.
The original article is pure speculation. Can life exist that is so different from the stuff we know, so that we can't detect it with current molecular biology techniques?
Sure why not. What the article fails to mention is that we can find life in other ways. Even if we can't sequence the DNA in many cases we can culture microorganisms from environmental samples. We can also use microscopy to directly examine environmental samples. In fact both the microbial cultures and microscope have been done on large scale over many years. Not once have we seen an organism that does not conform to our current understanding of life on earth. Life can also be identified by the changes in the environment it create. Again nothing we have seen so far has suggested that there is a life form so unusual that we can't detect it with our current techniques.
Where authors of the original article fail most miserably is their solution: high throughput sequencing techniques. Huh? How would those techniques lead to the discovery of life that is fundamentally different if they are dependent on the standard properties of DNA and DNA replicating enzymes??