quote:Originally posted by Alcon: I'm gonna have to disagree with you here. If alien life were discovered, we have no reason to assume that it wouldn't use DNA. As far as we know Earth is pretty much what the conditions for life are. A terrestrial planet, in a certain zone from the sun and with certain raw materials available in abundance (carbon, oxygen, nitrogen, water, etc). Life has shown a remarkable tendency to parallel evolution of traits that do their job well. DNA does it's job extraordinarily well. There's absolutely no reason to assume that alien life originating elsewhere wouldn't find its own way to DNA/RNA as a means of passing genetic information.
Certainly DNA is marvelously well-suited to its task, and as I said in my post, it wouldn't be shocking if it turned out that alien life used DNA (or a variant thereof) as its genetic material. That doesn't mean it's the only way- proteins, for example, are also long chains of monomeric units in which the sequence could conceivably used as a means for storing information. The same goes for polysaccharides- not to mention other nucleotides than DNA and RNA. These molecules aren't used for this purpose on Earth, but that's the end result of billions of years of evolution in a relatively constant environment. On a planet with different environmental pressures, it's entirely possible that another type of molecule might be evolutionarily superior.
quote:By the same line of thought, there's no reason to assume that if another method of passing genetic information exists, it couldn't have simply evolved and hidden away in some isolated nook or cranny of Earth. So even if this particulate matter is indeed alive and lacking DNA, that's still not necessarily a reason to jump to the assumption: alien!
Absolutely.
quote:Basically when judging the development of life we have an incredibly small sample size: a sample size of one. Experiments we done to recreate the conditions of life's genesis, last I'd read, had produced the same basic building blocks of life that we use (some very basic proteins and amino acids). Which suggests that the path to our form of life is: 1) likely to take place on other worlds in the same condition and therefore 2) to generate life with a similar basic cellular structure to our own.
Note that synthesizing amino acids from basic compounds has nothing to do with nucleic acids. Again, it's entirely conceivable that, given similar environmental conditions, a paradigm might have evolved in which proteins themselves are the information-carrying molecules of an organism.
quote:So I'm gonna fall back to this: till I get more information, I'm skeptical.
And so should we all. I'm speaking pretty much entirely in hypotheticals here. Posts: 1321 | Registered: Sep 1999
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So assuming that the red cells are alien... where would they have come from? How did they get into a comet?
Posts: 4953 | Registered: Jan 2004
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Who knows. I can say one thing for sure. If this really has an extraterrestrial origin (which is a pretty big if), then it will be one heck of an interesting area for future inquiry.
Posts: 2437 | Registered: Apr 2005
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Maybe the same place where the original cells that spawned life on Earth, and, if there was any, on Mars.
There's possible life, or evidence of former life, in a few places, just in our solar system. Could be that an asteroid hit a planet with life and ejected a piece of the planet with cells on it out into space, and over millions of years or thousands or whatever, they made their way to Earth.
I don't think it's that big of an if, for there to be life on asteroids. We've found microbes on meteors that have struck the earth before (well, at least once).
The big thing would be if we found life that is fundamentally different that what we currently perceive life to be. Or, if this stuff is more advanced than previous microbes found, how advanced?
Posts: 21898 | Registered: Nov 2004
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Ah ha! I finished that article orlox posted...and at the end it talks about how life could get into space.
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quote:Originally posted by Telperion the Silver: So assuming that the red cells are alien... where would they have come from? How did they get into a comet?
Perhaps they could have been deflected out of the atmosphere of a gas giant, frozen onto a comet or expelled by some kind of volcanic, or other natural explosion on any of the other planets in the solar system. Less likely, they could have arrived the same way from another solar system, although given the scale of things on that plane, this would mean that the entire galaxy is up to the gills with these things floating around. The chance of a random impact with the Earth's athmosphere of a single comet or asteroid from another solar system is akin to hitting the head of a pin with a rifle shot from a thousand miles away without aiming.
Posts: 9912 | Registered: Nov 2005
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"So assuming that the red cells are alien... where would they have come from? How did they get into a comet?"
The swallow may fly south with the sun or the house martin or the plover may seek warmer climes in winter, yet these are not strangers to our land?
Posts: 9754 | Registered: Jul 2002
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Again, it's entirely conceivable that, given similar environmental conditions, a paradigm might have evolved in which proteins themselves are the information-carrying molecules of an organism.![[Smile]](smile.gif)
