It contains nucleobases. But does it contain ribose, or ribose linked to the nucleobases, or to phosphates? And more generally, does it also contain a grab bag of related chemicals that are not building blocks? The existence of such blocks as minor constituents of a soup of random chemicals doesn't mean much, especially as the concentration of any such constituent declines exponentially with its complexity.
One longstanding theory is that life first began on Earth when asteroids carrying fundamental elements crashed into our planet long ago.
I'm no expert but this sounds strange. Surely those fundamental elements would also form in vast quantities on their own on an entire planet with volcanoes and oceans? Wouldn't a couple asteroids be the literal drop in the ocean in comparison?
The missing part is how do they form self-replicating mechanisms capable of evolution. I doubt an asteroid with a bit of organic dust is enough for that. If such small amounts suffice we should see the formation of new life forms from scratch, today, left and right I think?
I agree. If we knew the mechanism for how life started we'd probably be doing the experiments to prove it. There are theories and experiments that suggest some life-like processes can happen with inorganic compounds, but they require a lot of squinting and a bit of imagination to connect with our own origins. And there's a big difference between experiment and nature. On the one hand, we have people trying to make it happen, while on the other hand, it apparently already happened once, without anyone even needing to be around.
> One longstanding theory is that life first began on Earth when asteroids carrying fundamental elements crashed into our planet long ago.
That theory is bullocks. When an asteroid enters the atmosphere and crashes as high speed on the surface, you get a huge amount of energy that creates an explosion and a destruction of most complex chemical material in the process. It's no mistake that these kind of impacts are counted in the same range as multiple atomic or hydrogen bombs.
I wonder how they prevent contamination of the containers used to collect and store samples.
I assume they have to be ultra clean in every sense of the word 'clean' with the cavity pulled to a vacuum. And also the equipment that collects the sample and puts it into the canister has to be clean as well.
Fascinating that all five nucleobases were found in Ryugu samples. The fact that these formed abiotically in an asteroid environment strengthens the case that the building blocks of life are common throughout the solar system. The amino acid findings from the same samples were already compelling, but having the complete nucleobase set is a different level of evidence.
Ryugu showed an estimated ~20,000 different organic molecules. It's not that surprising that the nucleobases would be among them, along with all sorts of chemicals not relevant to life.
In the reference from the link for this HN entry, we see the nucleobases were present at concentrations of about 1 nano-mole per gram (< 1 ppm). They are minor constituents present in a sea of mostly non-biologically relevant compounds.
Doesn't multi-world interpretation pretty much answer how life originated?
I mean, even if the starting state require to bootstrap life have impossibly low chance to happen random, multi-world interpretation implies that there will be some worlds where it happened, and observation of life is only possible in such worlds..
That's not really new. It seems as if some people try to project "there is life outside of planet Earth". Well, the thing is ... is this question important? You already have life here. Synthetic biology will also progress. So why is it important if life is anywhere else? I don't understand it.
There is nothing magic in RNA or DNA. Granted, right now we can not easily explain how life gets "bootstrapped", but recently there was a paper of self-propagating RNA even of a kind of semi-random sequence; this RNA can just amplify itself. I am sure you can find many more similar examples eventually as well as biochemical reaction processes that can be "bootstrapped" - and I am also sure none of these work on an asteroid. So why is there this strange focus on "life outside of planet Earth"? Some people want research money, that is clear now.
Ummm ... the "Victoria University of Wellington in Australia"? Please. Victoria University is located in Wellington, New Zealand [1]. Nothing to do with Australia. Dr. Morgan Cable is a Senior Lecturer in Space Science at Te Herenga Waka, Victoria University of Wellington in New Zealand [2]. Can't believe that phys.org would publish such an error.
I'm in the middle of reading Peter Brannen's The Story of CO2 Is the Story of Everything—it's excellent and goes deep into the (bio)geochemistry of Earth—and he presents a good case for a metabolism-first development of life, taking advantage of "a disequilibrium that needed to be relieved at the vents, an unending stream d free energy to dissipate," rather than the RNA information-first theories.
It fits his overall narrative but it was an interesting way to think about life "as a thermodynamically necessary mechanism to relieve the continuous production of free geochemical energy on Earth... more efficiently than abiotic processes could." (Brannen quoting complex-systems scientist Anne-Marie Grisogono) I highly recommend the book.
This is similar to Nick Lane's books, and the research he references as well. The necessity for disequilibrium, the emphasis on life as the movement of energy across a barrier, etc.
I'm no expert but it seems most reasonable to me. The continual talk about pre-biotic soups of ingredients seems profoundly misplaced.
I’ve wondered before if the idea that life originated on Earth might be the last geocentrism to fall.
Speculation of course, but it would fit a certain historical pattern.
Maybe life is all over the damn place, just a thing that happens under certain thermodynamic constraints, and it arrived on board comets or some similar mechanism.
Maybe space contains spores of minimal super simple organisms that can survive being vacuum freeze dried for incredibly long periods of time. When they land somewhere suitable they do stuff.
Maybe life originated long, long ago. The wildest speculation I have is that it originated shortly after the big bang during a brief period when the temperature of the universe was temperate, but that’s very far fetched for numerous reasons. More likely that it pops up from time to time and spreads over cosmic time scales.
But it only evolves to high levels of complexity in environments that are very friendly to a lot of life, have abundant energy, and are stable enough for a very long time. That may be the rare thing.
Or like some ancient alien species that travelled the stars but found it was alone, like in the ST:TNG episode[0]? No too.
Even if these ancient aliens thought it would be fun to spread their sperm all over asteroids and fling them out into the universe, there wouldn't be enough time for those rocks to get anywhere.
The more logical conclusion is that abiogenesis happens everywhere in the universe under the right conditions.
So what?! This does not prove anything! There are stones all around us, but they don't assemble themselves into beautiful, majestic stone buildings! All ingredients of concrete are around us, but we don't see them turning into concrete and pouring themselves into freeways, bridges, and all kinds of much less complex than living organisms!
The most important question we all want answered is just how rare life is in the Universe.
The fact that the building blocks are there just floating around on asteroids makes it that much more likely that its quite common.
If you look at the paper, the nucleobases were present at concentrations of about 1 nanomole per gram. So, maybe 200 ppb by mass for each. They are in a sea of other random organic stuff that is at best tangentially relevant to life as we know it.
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[ 3.5 ms ] story [ 29.6 ms ] threadThe missing part is how do they form self-replicating mechanisms capable of evolution. I doubt an asteroid with a bit of organic dust is enough for that. If such small amounts suffice we should see the formation of new life forms from scratch, today, left and right I think?
That theory is bullocks. When an asteroid enters the atmosphere and crashes as high speed on the surface, you get a huge amount of energy that creates an explosion and a destruction of most complex chemical material in the process. It's no mistake that these kind of impacts are counted in the same range as multiple atomic or hydrogen bombs.
I assume they have to be ultra clean in every sense of the word 'clean' with the cavity pulled to a vacuum. And also the equipment that collects the sample and puts it into the canister has to be clean as well.
The logistics aren't obvious to me at all
https://www.science.org/doi/10.1126/science.abn9033
In the reference from the link for this HN entry, we see the nucleobases were present at concentrations of about 1 nano-mole per gram (< 1 ppm). They are minor constituents present in a sea of mostly non-biologically relevant compounds.
I mean, even if the starting state require to bootstrap life have impossibly low chance to happen random, multi-world interpretation implies that there will be some worlds where it happened, and observation of life is only possible in such worlds..
There is nothing magic in RNA or DNA. Granted, right now we can not easily explain how life gets "bootstrapped", but recently there was a paper of self-propagating RNA even of a kind of semi-random sequence; this RNA can just amplify itself. I am sure you can find many more similar examples eventually as well as biochemical reaction processes that can be "bootstrapped" - and I am also sure none of these work on an asteroid. So why is there this strange focus on "life outside of planet Earth"? Some people want research money, that is clear now.
[1] https://www.wgtn.ac.nz/
[2] https://www.psi.edu/staff/profile/morgan-cable/
It fits his overall narrative but it was an interesting way to think about life "as a thermodynamically necessary mechanism to relieve the continuous production of free geochemical energy on Earth... more efficiently than abiotic processes could." (Brannen quoting complex-systems scientist Anne-Marie Grisogono) I highly recommend the book.
I'm no expert but it seems most reasonable to me. The continual talk about pre-biotic soups of ingredients seems profoundly misplaced.
Speculation of course, but it would fit a certain historical pattern.
Maybe life is all over the damn place, just a thing that happens under certain thermodynamic constraints, and it arrived on board comets or some similar mechanism.
Maybe space contains spores of minimal super simple organisms that can survive being vacuum freeze dried for incredibly long periods of time. When they land somewhere suitable they do stuff.
Maybe life originated long, long ago. The wildest speculation I have is that it originated shortly after the big bang during a brief period when the temperature of the universe was temperate, but that’s very far fetched for numerous reasons. More likely that it pops up from time to time and spreads over cosmic time scales.
But it only evolves to high levels of complexity in environments that are very friendly to a lot of life, have abundant energy, and are stable enough for a very long time. That may be the rare thing.
Or like some ancient alien species that travelled the stars but found it was alone, like in the ST:TNG episode[0]? No too.
Even if these ancient aliens thought it would be fun to spread their sperm all over asteroids and fling them out into the universe, there wouldn't be enough time for those rocks to get anywhere.
The more logical conclusion is that abiogenesis happens everywhere in the universe under the right conditions.
[0]: https://en.wikipedia.org/wiki/The_Chase_(Star_Trek:_The_Next...