The NSF/NASA Center for Chemical Evolution at Georgia Tech has published some exciting news for origin of life studies in the April 25 'Nature Communications'. This relates to the 'RNA world' hypothesis, the widely shared idea that RNA preceeded DNA as a proto-biological chemical replicator and that the earliest evolution of the genetic code took place in RNA. Speculation these days is that RNA might have had its own chemical replicator precursers, that no longer exist in present-day biology. These are termed 'proto-RNA' and have similar but different nucleotides. The new development announced today involves barbituric acid and melamine in place of RNA's familiar adenine and uracil. Apparently it's believed that barbituric acid and melamine might have been abundant in the early prebiotic Earth. Experiment shows that barbituric acid and melamine combine with the sugar ribose very readily. Not only that, they pair with each other with hydrogen bonds to form something very similar to Watson and Crick base-pairs in a ladder structure. And perhaps most significantly, this proto-RNA polymerizes in water to form long chains. One of the biggest problems with the RNA-world origin-of-life theorizing is that regular RNA won't seem to polymerize in water. But here we have something that might be an RNA precurser that does. There are still big gaps in the story, most notably how and why adenine and uracil took the place of barbituric acid and melamine. But I think that this is a big step towards understanding how life might conceivably have orignated. http://phys.org/news/2016-04-links-brewed-primordial-puddles.html
No thing new melamine combines with aldehyde groups forms a resin , barbituric acid with 3 vulnerable keto groups there should not be any surprise .. Will you then get ribose from a comet ?
I believe Robeert Hazen demonstrated this in his Video "Chance, Necessity and the Origins of Life" https://www.youtube.com/watch?v=TlAQLgTwJ_A Any self replicating system which is able to use a variety of chemicals and therefore will show different *mutations* at such a basic level would account for the exquisite variety of life, just on earth alone. Then also the evolution of life on other planets acquires a greater probability.
I have watched this presentation the big emphasis was forming certain crystals. Lets assume naturally you formed some unique crystal . I would call it a catalyst, Then if you don't bring monomers to it the catalyst will be just there . To my mind as an example (Zigler Natta ) to polymerize propylene to produce polypropylene . This catalyst is effective to use only some particular monomers . When we talk in producing a protein you have a very complex catalyst, were an assembly plate is required such a Ribosome . Beside first you have to have a system that have to pump in energy so some action will take place and second you need some that will feed monomers.
Seems to me you missed the underlying point of the presentation which was "Chance, Necessity and the Origins of Life". Your objection is meaningless on a universal scale. The earth itself has undergone some 2 trillion, quadrillion, quadrilion, quadrillion chemical *experiments* during its relatively short existence. Try to multiply that number on a universal scale. I would agree with Hazen that the *probability* of forming biomolecules is on the high end of the scale. And all you saw was how crystals are formed? I would suggest to see Hazen's presentation again with a more *open* (attentive) mind.
I am not sure I need it . They can hand wave as much as they want and tell billions of year to make their point . In a bell shape of probability you have a front end and a lagging end. Basing an argument on such a long time I don't go for
So you want to prove it in a lab? And there is no Bell curve. There is only a range of probabilities and most of the probabilities of forming biomoecules lies within that range. But that range can only exist if you take the entire universe and chemical reactions taking place therein over a timespan of some 13 billion years. That was the whole point of the presentation. It is impossible to duplicate all the chemical reactions and required conditions for such possible chemical reactions. We haven't even discovered all the chemicals peculiar to the earth itself, let alone what goes on in a nebula. All we can hope for is to assemble a self replicating biomolecule of some sort. He did say that RNA was his personal preference, but did not rule out several other means of achieving a selfreplicating biomolecule . The rest is just mutation, natural selection, and time. Apparently the conditions on earth allowed the formation of biomolecules short of a billion years.
There are limits what can be done in a lab. Just look what time and investment it took to prove the *existence* of the Higgs boson, a single particle. That was the point of the presentation, the enormous scale and time available to the universe to *experiment* at near infinite numbers makes it highly probable that somewhere biomolecules come into existence. We have clear evidence one of those locations was earth. But earth is just an average rocky planet . There was nothing special in earth's formation and orbit. It was just right for us, but we have already discovered several solar systems with *cinderella planets*. Is there any reason why those planets could not produce life, given their size and time to perform natural *chemistry* experiments at unimaginably large numbers, similar to earth? When and where there is matter, there is chemistry.
No it isn't. There is plenty of good science done for which a laboratory is of very little use. Geology and astronomy are examples.
Nonsense! Geology is extremely well established and contains little speculation. Likewise most of astronomy. You may perhaps be thinking of cosmology but most astronomy is a lot more directly connected to observation. What about palaeonotology, too? Again largely field work and certainly no replication in a laboratory.
you are right I was thinking about cosmology, If you are thinking about rocks processing I am with you in other words Identify materials and mining them and so on, but about earthquake , identification a time period if deposition that is an ifi.
Earthquake prediction is very difficult but that does not mean the science of geology is speculative. We know very well why it is hard to predict earthquakes. The movement of tectonic plates is at a rate only a few cm/yr (we've measured it - not in a lab of course) and so these processes take place on a timescale of millions of years. Thus, it is hard to predict when an individual earthquake will occur on a human timescale. Nothing speculative about that, it seems to me.
Why is it even important to know when a tectonic event *will* occur? From the exposed strata today, we can pretty accurately guestimate when such an event happened in the past, even if this event was millions of years ago. We can know the age of trees by counting their rings, and similarly we can approximate the the age of large events by looking at the exposed strata (earth's geological rings) which was pushed up or was subducted. But long before an geological event (such as tectonic shifts) enormous pressures and heat build and many basic chemical reactions yield differentl results at different pressures and heat. From wiki; This process has been going on for millions of years and continues today.
It was timojin who raises the issue of earthquake prediction, not me. If it were possible it might save many lives, but this is drifting off-topic. Yes, indeed, carbon has an almost unique tendency, among all the elements, towards catenation, including the formation of polymers. We used to speculate at school about alternative life chemistry but tended to come back to carbon because of catenation. Si does it a bit, but not as much.
@ exchemist, Hazen mentioned that the human body consists of some 500 different molecules. Is there no way to identify these molecules? If we could, then it becomes just a puzzle with 500 pieces, which for a dedicated computer should be possible to solve, given enough time to test all possible configurations. I am sure it is more complicated than that, but what stands in the way of this approach? Turing solved the Enigma code. Of course that was just based on the 26 letters of the German alphabet and they did find a *key*, while with a living organism we are dealing with some 500 *letters*, exponentially raising all possible combinations, with perhaps several seperate keys involved. We have some keys,, such as the tetravalence of carbon and Im sure we know the valence of several other common biomolecules. If we could find the approximate location where life first appeared, would that not narrow down the conditions and available biomolecules at those locations, at the time life first appeared? Can you offer an insight into the fundamental obstacles to such analysis of possible chemical processes at specific locations. Hazen sounded optimistic, but from a skeptical viewpoint, do we know enough or do we need much more information?
