Earth is the only example that we have studied. Anything else can only be in the realm of pure speculation for some time. Once we have more than one example of life, preferably once we have several examples of life, then things like panspermia become a better topic for research.
Right now it can be nothing more than speculation.
But what about the "panspermeability" of the life we know, frin Earth? How likely is the possibility of natural spreading through other planets, after impacts? There are organisms that could survive, or at least, significant parts of organisms (such as DNA) that could infect other planets and spread? Or most of the DNA of actual organisms is much adapted to their respective organisms to be "useful", in terms of genetic code, to a pre-biotic stage of some planet? I'm not even thinking in this DNA producing something highly similar to what it did originally, but only to code for something, in a more organized way...
There are organisms that could survive, or at least, significant parts of organisms (such as DNA) that could infect other planets and spread?
Remember that whatever part(s) of an organism must also survive entry into a planet's atmosphere and the impact onto the planet. Although this is somewhat outside of my field, I'd be surprised if we do find anything that could survive (1) the vacuum of space, (2) the extreme temperature of atmospheric entry, and (3) it's impact on the planet.
For goodness's sake, please vote Democrat this November!
Considering the time spans required for distribution of starter material through pansperpmia would be similar to the times needed to do the same initial work through natural processes, I don't see it being likely. I would imagine that it is just as likely that any starter system delivered between habital worlds wouold find the ecological niche already filled. It would then depend on which starter body competed best to fill the niche.
But what about just latent genes? That wouldn't be exactly a "survival", but just "conservation".
There's the already mentioned in this topic idea of Hoyle (or someone else... maybe a bit derived from someone other's idea) that's more or less like this, except that he/them put this as a frequent event, with genes coming from the space, being responsible for great part of evolution, or even "driving" the evolution (and I don't see that happening). I thought that the most polemical part of this idea is the part of genes everywhere in the universe, existing "since forever ago", in a stationary universe; but the survival of genes I thought that was more or less possible (but maybe it just doesn't look that odd compared with the whole rest of the hypothesis).
I remembered of this with this news about sugar being found in the center of the milky way. Abiogenesis is thought, at least as a possibility, to maybe having made some use of compounds, such as sugar, coming from space... and since DNA is more or less like a complex sugar... I thought if it could remain more or less intact like other simpler compounds maybe did. The main problem I guess was the conditions of the earth when these compounds came here (if that happened)... perhaps it only could reach due to atmospheric conditions that differ from the expected atmospheric conditions of a stage which the arrival, or the "insertion" of a genetic code could be useful... wow, there are many things to account to answer this..... =-/
But, anyway, despite of the problem of reaching another planet intact (or at least some "meaningful" sequences), I was thinking what a genetic code (or a fragment), evolved elsewhere, would do if inhited horizontally by some organism, or arrived at a pre-biotic stage, with "already-done" metabolisms "waiting". The DNA basic instructions itself are universal, but would be the genetic code itself reasonably "compatible", because of that? Of course I'm not expecting phenotypical equivalence in other thing than the proteins coded (if so... I really don't understand that much)...
... so, basically, my question is if that somehow manages to happen, would a alien genetic code be "used", in something like accelerating the ability of self-reproduction, if arrived in a pre-biotic stage, or the code would be completely discarded, and the DNA would be decomposed and used as simple sugar?
This message has been edited by extremophile, 09-28-2004 07:41 PM
This message has been edited by extremophile, 09-28-2004 07:44 PM
I don't get all the fuss here. To suggest that fully formed DNA would come from space is reaching way beyound what evidence we have.
And, of course, abiogenesis made use of compounds from space. Everything here came from space! Geez.
It is interesting that the early earth could have gathered up a number of useful small molecules after they had formed in space. This allows for very large quantities of them very early in earth's history. Beyond that I don't think it is anything to get very excited about.
What would be interesting is what would the density of the sugars (for example) be, would they be caputured or be pushed away when the solar wind fired up? If they form in space is it necessary they came from there? Why can't they have formed here as well?
Yes, panspermia is a fascinating idea and its most prominent proponent is a guy named Rhawn Joseph. He talks about DNA being a universal code impossible to create or destroy and viruses being the memory bank and seed of life travelling through cosmos and so on. Seems a highly reasonable line of thinking.