Ingredients of Life Found Around Sun-Like Star 366
smooth wombat writes "NASAs Spitzer Space Telescope has detected the basic organic building blocks of life in a ring orbiting in the 'habitable zone', that area where Earth orbits the Sun and where water exists on the borderline between gas and liquid, in a nearby stellar nursery. When acetylene and hydrogen cyanide combine with water they form adenine, one of the four bases of DNA. The detection supports the widely held theory that many of the molecular building blocks of life were present in the solar system even before planets formed, thus assisting the initial formation of complex organic molecules and the start of life itself." Though it was a little shakier than this observation, we've discussed the possibility of life elsewhere in the galaxy before.
Drake equation (Score:5, Interesting)
DNA in space? (Score:5, Interesting)
I think the current popular theory, IIRC, is that RNA molecules somehow stack up in a tidal pool, where they are gently rocked back and forth. Some correct me please.
So how hard would it be to get DNA to link up in microgravity? Sure, there's more radiation around to blast things apart, but that might be a good thing -- you could get molecules you might not get otherwise without the blowing apart. Also, in microgravity, molecules can float around in 3 dimensions.
After further consideration... (Score:4, Interesting)
The detection supports the widely held theory that many of the molecular building blocks of life were present in the solar system even before planets formed, thus assisting the initial formation of complex organic molecules and the start of life itself.
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Wait, so finding organic molecules around a planet supports this how? Can we tell the age of those particles, or that stellar nursery? If we are to believe a lightning strike can create life from amino acids and things of this nature... why would this support that conclusion in particular?
Maybe I'm missing the point. Perhaps someone can explain things to me?
Life is software, not hardware (Score:5, Interesting)
Re:Wait - so Moby had it right? (Score:4, Interesting)
Actually, even the bible tells us this is so. "Ashes to ashes... dust to dust...".
Could interpret this literally and say that we (the Sun, Earth and life on it) are made from interstellar dust initially, and that's where we end up when the solar system ends its life and turns back to ashes and dust when the sun explodes.
It is agreed in all probability (Score:4, Interesting)
1. Gravity of at least 0.4 G is a requirement (micro-gravity need not apply here as a recent ISS scientific experiement shown with regard to catalyst of acytelene/water/hydrogen under electric sparks/shocks)
2. Swirling motions (tidal pool is nature's best liquid/air agitators)
3. Minimal radiation (asinine will not remain cohesive for long under gamma bombardments)
This means a heavy shielding must be in place, which means dense air and/or planet
4. Lightning... the very most improbable of all aspect of the building block starter. It's gotta strike at the right place and the right time, preferably near the tidal pool.
I'd gotta hand it to mother nature and God, we are one lucky fools on this unqiue planet, Earth.
Re:DNA in space? (Score:2, Interesting)
This is despite the vacuum and the exposure to extremes of temperature!
-Nivag
Re:Ingredients of Life Found Around Sun-Like Star (Score:2, Interesting)
It seems to be the same question as, "Where did did the inteligent designer come from?"
Re:DNA in space? (Score:4, Interesting)
Re:statistical black hole (Score:4, Interesting)
Life can start simple. A single molecule that reacts with other molecules around it and makes imperfect copies of itself is enough. Given time, all suitable molecules will be used and live, even if primitive, will be everywhere.
Since the copies are not perfect, mutation does happen and you will have a lot of different "copiers" in your soup, some better that the others, some building more complex structures that can, in turn, copy themselves.
I agree with you. Expecting cell based lifeforms in the first week of a biosphere is ludicrous, but you are wrong. Cells, nuclei and DNA are only one way of life to express itself. It happens to be the way we know because once a certain kind of life dominates, there is little space left for other forms. It happened here.
There are sure other forms of organization that happened all over the place. Remember: billions of places over billions of years make a lot of attemps on life.
Re:In other news (Score:4, Interesting)
First came RNA, which combines the catalytic properties of proteins and the hereditary properties of DNA in a single molecule. So RNA can provide a template for new RNA (by base complimentarity) and also catalyse the polymerization of RNA onto itself. The odds of randomly assembling such an RNA are of course excruciatingly low - but we have a hundred million years and many, many RNA polymers floating around during that period. Furthermore, if we were on a planet where this had never occurred - would we be here to talk about it?
RNA molecules form spontaneously in conditions like those on the early earth, given the right organic ingredients (i.e. in the presence of the molecules we see in that gas cloud, if they were on a planetary surface).
Phospholipids (or other molecules, with similar charge properties) also form spontaneously, and arrange spontaneously into lipid bilayers.
Since these lipid bilayers would have a strong tendency to concentrate whatever was in them when they floated away, the insides of these lipid bilayers would be ideal locations for these self-replicating RNA to congregate. I will refer to these proto-cells as "collectives of RNA molecules".
Over time, these RNA molecules evolve new catalytic activities. It has been well established - in experimental studies - that randomly varied RNA can, indeed, evolve new catalytic activities. It takes a while, but we've got an aeon to burn.
Three new RNA activities are key:
a) Creating a "template" version of themselves/eachother consisting of DNA, rather than RNA. This will eventually become the inherited genome - but originally, this would confer a selective advantage because DNA molecules are more stable than RNA. Even today, no organism can synthesize DNA without first synthesizing a little RNA as a "primer" to get synthesis started.
b) Making proteins as an aid to catalysis. The first proteins were probably non-informative polymers (like starch). Most likely, they served as bound cofactors (like heme iron in hemoglobin) and the like for RNA enzymes. Since proteins are almost universally superior catalysts to RNA, the first collective of RNA that had the ability to synthesize protein would have a great advantage. Even today, the fundamental reaction of protein synthesis is catalyzed by the RNA component of the Ribozome, although modern Ribozomes have a great many proteins that "help" the process.
c) Synthesising additional phospholipids to make more membrane. As time goes on and the amount of free phospholipid floating in the water declines, this becomes a great selective advantage to any proto-cell, since it can reproduce more proto-cells limited only by available energy and reduced carbon.
With these three - perfectly understandable - adaptations, you have evolved from a soap bubble full of RNA into a cell.
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Obviously, this story need not be true, and there are many details missing (or incorrect.) At the moment, however, it is the best explanation we have, and it is certainly possible.
Re:Ingredients of Life Found Around Sun-Like Star (Score:3, Interesting)
Therefore a deity could be an intelligent designer of the universe. I don't see any more or less proof for that then the big bang theory
Disclaimer: I do not believe in a supreme being.
Re:DNA in space? (Score:3, Interesting)
I agree that the anaerobic formation of life is a more plausible scenario, given how utterly caustic oxygen is (thanks to its valence electron configuration).
However, given the dependence of organic molecules on that particular atom with atomic weight sixteen, I think you'd be hard-pressed to claim that all oxygen is detrimenal to the formation of life; redox reactions, as basic as they are, are still essential in organic chemistry. So, while an oxygen atmosphere would have likely destroyed early self-replicating molecules, they would never have formed without access to oxidized compounds.
(As a footnote, I only *started* as a Chem major, and switched to Math, so my Organic is more than a little rusty).
adenine is not complex (Score:3, Interesting)
It isn't really the step from the simplest of molecules, like water, to slightly more complex molecules, like amino acids, which is the problem. Experiments starting with Stanley Miller's have shown this is an easy step.
Very likely the tricky step is forming an enclosed system in which information is passed back and forth from some information-storage molecule like DNA to some actuator molecules, like proteins. Not only have we never seen such a system, outside of life and deliberately-constructed life analogues, but we have no idea how it could even come about.
It's hard to even imagine a plausible evolutionary sequence that leads from random organic molecules to this kind of system. The problem is that the benefits of being "alive", in particular being able to reproduce yourself are clear, but it's hard to see any benefits to being "halfway alive", e.g. to having half of the necessary molecules for reproducing yourself. That makes it hard to imagine any intermediate steps between non-life and life that would be favored by natural selection. And if there aren't any good intermediate stages, then life has to originate all at once, zap, in some wildly unlikely coming together of an entire living system. This is almost equally hard to swallow (unless you want to invoke the hand of God).
A good analogy is with wings: how do wings evolve? The problem is that on first glance it doesn't seem useful to have only one wing, or wings too short to lift your mass. So how could a wingless creature evolve by small stages towards having wings? It would seem that wings would have to originate all at once, zap, in some wildly-unlikely set of mutations that would give a species wings in one generation.
However, I believe the current belief is that wings started off as cooling fins, or possibly steering vanes for animals that leaped through the air. In which case, of course small fins or vanes are useful, and one can see the intermediate stages that would allow full wings to evolve gradually. What's needed in evolutionary biology is some similar insight into how certain groupings of molecules well short of what we'd call a living system could, nevertheless, have an evolutionary advantage.
What's also needed is some idea of why we don't see this kind of process going on all the time on Earth. Why don't we see things halfway to living all the time in the muds and stagnant ponds of the Earth? One possible answer is that the best conditions for the evolution of life (e.g. no free oxygen) are no longer present.
Re:DNA in space? (Score:3, Interesting)
Re:adenine is not complex (Score:3, Interesting)
I'm not sure what half-way alive even means. If you start with the premise that you have some primitive self-replicator, then being "alive" (as we understand modern organisms to be) might not even apply. And, as with all physical processes, abiogenesis would not be a completely random series of events. Chemistry and the laws of physics would still apply, and thus, by the very nature of organic chemistry, some combinations are going to be more "favored" than others. You have to discard notions of what life has been for the last 3.5 to 3.8 billion years. Primitive self-replicators more than likely relied upon relatively simple interactions, and even such things as division could have been mechanical (ie. wave motion). We know many chemical processes that in some way or another resemble living systems; fire and crystal formation come to mind, and at the end of the day, life, no matter how simple or complex, works on the basic principle of converting chemical energy.
The point of all of this is that once you have the ball rolling, and you start having complex organic molecules capable of some form of replication, then the underlying assumption is a run-away effect, that these proto-replicating molecules will start competing for resources, and that certain molecules will have, due to imperfect replication (which is what evolution is all about at the heart of it), a greater ability to access resources.
This is, of course, always going to be speculative. The earliest self-replicators were not the kinds of entities that would ever leave direct fossil evidence, and the first organisms that did leave evidence (mainly by their waste; oxygen) were already pretty darned advanced. It's quite conceivable that there might be a number of ways to go from an organic chemical brew to living systems. Organic chemicals do all sorts of strange things when introduced to energy, and if there's one thing that the early Earth did not lack, it was sources of energy.
Comment removed (Score:3, Interesting)
Re:Ingredients of Life Found Around Sun-Like Star (Score:3, Interesting)
Why are some people incapable of believing that the universe could be infinite in both "directions" of time--that is, capable of always having existed--and then turn around and in the same breath be capable of believing that a noncorporeal, intelligent and benevolent entity could?
Not saying you are such a person. Just that this obvious disconnect of reason baffles me.