Posted: May 02, 2012 5:09 pm
No, they work from the assumptions made.
CharlieM wrote:Rumraket wrote:CharlieM wrote:Its too remote to do anything else
The conditions extant on the early earth has left evidence in ancient rocks, or specifically the crystals contained in them, like Zircons. That makes it at least partially observational. These observations can then be used as starting points when doing experiments.
In a ScienceDaily news item, Setting the Stage for Life: Scientists Make Key Discovery About the Atmosphere of Early Earth, they have this to say:For decades, scientists believed that the atmosphere of early Earth was highly reduced, meaning that oxygen was greatly limited. Such oxygen-poor conditions would have resulted in an atmosphere filled with noxious methane, carbon monoxide, hydrogen sulfide, and ammonia. To date, there remain widely held theories and studies of how life on Earth may have been built out of this deadly atmosphere cocktail.
Now, scientists at Rensselaer are turning these atmospheric assumptions on their heads with findings that prove the conditions on early Earth were simply not conducive to the formation of this type of atmosphere, but rather to an atmosphere dominated by the more oxygen-rich compounds found within our current atmosphere -- including water, carbon dioxide, and sulfur dioxide.
So scientists had made assumptions about the atmosphere on the early earth for decades. And they used these assumptions to set up their experiments. Now these assumptions have been turned on their heads. Until the next time when the new assumptions will no doubt be superceded.
Why should they? The strange thing is you seem to think life did actually originate in some way which I gather you think was extremely fortuitous and therefore "planned/primed", though not strictly interventional. Whether that's correct or not, why can't these latest findings you link actually constitute some of the relevant conditions that were extant on the early earth? Do you think finding out is impossible?
CharlieM wrote:Rumraket wrote:CharlieM wrote:The proposed RNA molecules would be delicate things, how long would they be able to remain in a dormant state?
I see you're arguing from a position of an RNA-first hypothesis. Even if we just run with that, they're still not assumed to be free living, bare molecules. They're envisioned to be enclosed in fatty acid vesicles which live inside precipitated mineral structures near hydrothermal vents. They don't get to survive leaving these conditions until the molecular machinery that allows this has evolved.
I am going with the RNA-first hypothesis because I thought that was the most popular hypothesis at the moment. I'm sure conditions inside these mineral structures would be vastly different from conditions outside in the wide ocean. So the proto-organisms must have fortuitously developed the ability to survive in these external conditions before they actually ventured out into them. They would have had to be pretty sophisticated to be able to survive in both of these diverse environments. After leaving the comfort of their mineral homes they would need energy to build the molecules they needed for survival. Assuming this energy come from chemical reactions there are a few questions I have. How did they convert it into energy they could use?
One hypothesis is that photosynthesis evolved very early(before life left it's mineral habitats, see This and This. ), providing the necessary energy to fuel metabolism. Some of the earliest evidence for life is of photosynthesizing life at >3.7 Ga.
http://isites.harvard.edu/fs/docs/icb.topic463355.files/Readings%20for%20Discussion%20Sept%2022/Rosing%20and%20Frei%202004.pdf
U-rich Archaean sea-£oor sediments from Greenland ^ indications of 3700 Ma oxygenic photosynthesis
Abstract
s3700 Ma metamorphosed pelagic shale from West Greenland contains up to 0.4 wt% reduced carbon with N13C
values down to 325.6x [PDB, PeeDee Belemnite]. The isotopic signature and mode of occurrence suggest that the
carbon derived from planktonic organisms. The Pb isotopic composition shows that the shale had high primary U/Th.
This indicates that organic debris produced a local reducing environment which precipitated U transported to the site
of sedimentation by oxidized ocean water. The existence of highly productive plankton that fractionated C isotopes
strongly and set up oxidation contrast in the environment suggests that oxygenic photosynthesis evolved before 3700
Ma.
Interestingly this evidence of life is older than how far back we can go with phylogenetic reconstruction. This indicates photosynthesis evolved at least as early as DNA, and possible as far back as the RNA-world itself.
CharlieM wrote:How did these early replicators distinguish between needed chemicals and harmful chemicals and to ingest just the beneficial ones?
Maybe they didn't initially. Maybe those that didn't died out. That's normally how evolution works. The question is which/how many "harmful chemicals" were present?
CharlieM wrote:Were there enough of these required chemicals around away from the original specialized environment? These questions may or may not have been reasonably answered. Either way I'd like to know what the answers are.
I can't give you a complete picture here, I'm not that familiar with the subject. I can point you to litterature that attempts to answer some of these questions though. But as before, they're speculations of course, or "assumptions". The question is whether they're unreasonable. Most OOL scenarios to build on knowledge of extant processes on earth, like the existence of chemical and thermal gradients, geochemical processes etc. etc.
I'm afraid that teleology is either entirely in your own head, or evolved instinctual behavior. It seems to me there's a qualitative difference between stating that some given chemical reaction or physical process has been infused with intentions, or to say that a wasp intends to build a nest. The wasp may in some sense know what it's doing, perhaps at an extrely primitive level, but I can't see how sperm entering an egg could ever be said to contain the same level of intentions except in the most allegorical/metaphorical sense.
That's like saying a boulder intends to roll downhill. Both of them have evolved by fitting together. This process doesn't require some overarching design or planning.
CharlieM wrote:Rumraket wrote:CharlieM wrote:Okay so they could synthesize ribose, but you have to assume that in the wider environment there were ample amino acids and phosphates too.
Why do I have to assume that? Why can't they have evolved the ability to synthesize these compounds themselves from the bottom-up, like chemoautotrophs do today near hydrothermal vents and in the earth's crust?
So, while still in their original environment, did they also evolve the necessary mechanisms to use chemicals other than they were used to dealing with?
I think there's a gradient in contemporary models, where organisms at the "root" of the origin are dependent on organics supplied by geochemical sythesis, and as they get further away in the network of mineral structures, they're gradually exposed to greater concentrations of external compounds and inversely, a drop in the amount of the original compounds, providing a gradual shift in the extant selective pressures.
In your posts. Unfortunately, in nature the teleology you apparently see is of your own making.
Wow, a PhD and all.
Seriously, all they did was ask the question if amino acids could have been supplied from space and then proceed to do some experiments with high-energy impacts. They haven't got a model for the origin of life in there, which means they aren't making assumptions of relevance to the specific models I have alluded to. Whether amino acids could have been delivered from space or not doesn't change anything with respect to the scenarios I have described. There's nothing that would prevent both processes from taking place. So amino-acids could have been delivered from space and produced in atmospheric and geochemical reactions. Turns out life is even more plausible then.
Blind assertion again. There's no reason to assume they were planned, and the process itself isn't evidence that the process was planned. You seem to have a hard time grasping this elementary concept. I can throw a rock over a wall and hit someone in the head without it ever having been my intention. This demonstrates how an event cannot in itself serve as evidence of any intentions behind the event. This should settle this matter to any rational person.
The event itself cannot serve as evidence that the event was intended.
The event itself cannot serve as evidence that the event was intended.
The event itself cannot serve as evidence that the event was intended.
The event itself cannot serve as evidence that the event was intended.
The event itself cannot serve as evidence that the event was intended.
Seriously, I can't emphasize this enough, because it's the one fundamental mistake you keep making.
CharlieM wrote:Rumraket wrote:
Your caricture doesn't mean it didn't happen, and the event itself isn't evidence that it was planned. It's a bit like the extremely improbable series of events required throughout the history of the planet that lead to the 2004 Indian Ocean earthquake and tsunami.
The only reason you happen to ascribe any meaning to the origin of life is because you supposedly resulted from it. It's a bit telling why you aren't all up in your arms about the very special conditions that, for example, produced the great red spot on jupiter. Was that intended too?
Speaking of Jupiter, here is someone who thinks its presence is necessary for life to develop on earth:Solar systems that lack a Jupiter-sized object that can perturb mineral-rich asteroids inward toward terrestrial planets also have dim prospects for developing life, Lauretta added.
Yes and as it turns out, plenty solar systems have Jupiter sized (or actually bigger) gas-giants. Check the masses on those motherfuckers.
CharlieM wrote:Rumraket wrote:
I think you'd be even more surprised if we found we were the product of events that couldn't lead to us. The realization that conditions that favored the origin of life, were extant at the origin of life really shouldn't surprise anyone. Ever heard of Douglas Adams puddle?
Its no surprise that Douglas Adams puddle fits so well into its environment. What it should ask itself is, "Why have I been given the ability to ponder my own existance?
No, because that would constitute an unwarranted loaded question. The first question should be "How did I come to ponder my own existence?". There's no reason to presuppose it was "given", or that it's a "why" question at all.
CharlieM wrote:After all I would fit in just as well whether I was aware of the fact or not. My existence does not depend on my awareness, so why do I have this ability?
And you would live equally well with a lot less sand under your toenails, yet there it is. That doesn't mean it was anythings intention.