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Ryugu asteroid samples contain all DNA and RNA building blocks

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Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#71

Post by pfdietz »

shevy-java wrote: post #66
0x000xca0xfe wrote: post #8

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 se…

Yep, you are 100% correct. In fact, it is much more likely they were originating on Earth itself than a random hobo asteroid. > The missing part is how do they form self-replicating mechanisms capable of evolution. Well, there are some missing parts, yes, but RNA can self-replicate already; at the least some RNA can. Ribosomes also contain RNA so its is a ribozyme.

RNA can replicate in highly artificial conditions that would seem to already require life to occur.

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#72

Post by pfdietz »

kjkjadksj wrote: post #63
0x000xca0xfe wrote: post #8

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 se…

The missing part has been conducted in other experiments. I don’t have time to give you some papers, but nucleic acids can self assemble into long chains under the right condutions. No polymerase enzyme is needed.

The conditions, while not requiring enzymes, are still highly artificial.

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#73

Post by pfdietz »

adrian_b wrote: post #62
0x000xca0xfe wrote: post #8

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 se…

There are 2 distinct kinds of claims made about the role of meteorites fallen on Earth whose origin is in such bodies like the Ryugu asteroid. One claim, which is likely to be true, is that in the beginning the Earth had a lower content of volatile elements, e.g. hydrogen, nitrogen, carbon, oxygen and sulfur, than today. The reason is that Earth has condensed at a high temperature, being close to the Sun, and those e…

> This second claim does not make sense. The meteorites rich in water and organic substances are extremely easily vaporized during atmospheric entry or during the impact with the surface and their content of organic substances would decompose.

Such meteorites fall to Earth even today. Their interiors are often ice cold.

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#74

Post by Amorymeltzer »

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.

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#75

Post by Refreeze5224 »

fusslo wrote: post #21
ceejayoz wrote: post #11

Earlier quoted context omitted.

They seem pretty confident. There's been some conflicting reporting on contamination of the Ryugu samples over time. https://phys.org/news/2024-11-ryugu-asteroid-sample-rapidly-... > Researchers from Imperial College London have discovered that a space-returned sample from asteroid Ryugu was rapidly colonized by terrestrial microorganisms, even under stringent contamination control measures. https://www.isas.jaxa.jp/…

ty ty! I usually just give a quick chatgpt buy my work blocked every ai but copilot

Please don't just post slop anyone else could have gotten from AI. It undermines the entire purpose of this site, and reduces the quality of discourse drastically.

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#76

Post by soco »

adrian_b wrote: post #58
BinaryAsteroid wrote: post #40

Earlier quoted context omitted.

The smaller rocks are composed of those materials in solid state (e.g., ice not water). They are less irradiated as they are further away from the Sun (think the asteroid belt and beyond). Atmospheric entry (if that's what you mean) is irrelevant. What matters here is the transport of materials from a place where they could have formed, to a place where they couldn't.

Atmospheric entry is completely relevant because some people have made the illogical claim that meteorites falling on Earth could have contributed with such complex organic substances, like the nucleobases, to the appearance of life on Earth. The icy bodies from the outer Solar System that contain such organic substances are very easily vaporized during entry in the atmosphere of the Earth, so only a negligible fract…

So we get organic vapors in the atmosphere right. Shouldn't that matter?

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#77

Post by adrian_b »

marcosdumay wrote: post #61
8bitsrule wrote: post #45

Earlier quoted context omitted.

The major flaw in Panspermia is that it all had to start somewhere without Panspermia. If it did that there, why not here?

We know 2 things that are apparently incoherent: 1 - Abiogenesis is incredibly rare. We don't know how much exactly, but it's a lot. 2 - Abiogenesis happened on Earth about as soon as it became possible. Where "as soon as" means within half a billion years, but it's still way quicker than its rarity implies. A lot of people think panspermia is what made those two happen. Life had about a full billion years to appear…

Life cannot appear in any of the small bodies that become meteors, because there is no source of energy for it.

Life can appear only on big planets or on big satellites, like the big satellites of Jupiter and Saturn, if they have a hot interior and volcanism.

Volcanism brings at the surface substances that are in chemical equilibrium at the high temperatures of the interior, but which are no longer at chemical equilibrium at the low temperatures of the surface, providing chemical energy that can be used to synthesize macromolecules.

Solar energy cannot be used for the appearance of life. Capturing light requires very complex structures that can be developed only after a very long evolution and which cannot form spontaneously in the absence of already existing living beings.

The only theory of panspermia that is somewhat plausible is that life could have appeared on Mars, which had habitable conditions earlier than Earth. Then, some impacts on Mars have ejected fragments that have fallen as meteorites on Earth and some remote ancestors of bacteria have survived this interplanetary trip.

There are many meteorites on Earth that have their origin in impacts from Mars, so at least this part is known as being possible.

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#78

Post by adrian_b »

soco wrote: post #76
adrian_b wrote: post #58

Earlier quoted context omitted.

Atmospheric entry is completely relevant because some people have made the illogical claim that meteorites falling on Earth could have contributed with such complex organic substances, like the nucleobases, to the appearance of life on Earth. The icy bodies from the outer Solar System that contain such organic substances are very easily vaporized during entry in the atmosphere of the Earth, so only a negligible fract…

So we get organic vapors in the atmosphere right. Shouldn't that matter?

One theory is that the primitive Earth contained much smaller quantities of the volatile chemical H, C, N, O and S, which are the main constituents of water and of organic substances.

Then Earth collided with a great number of small bodies formed in the outer Solar System, which were rich in water and organic substances. This has modified the composition of the Earth towards the current composition. (Later Earth has lost a part of its hydrogen; because hydrogen is very light, it is lost continuously from the upper atmosphere, after water is dissociated by ultraviolet light; thus now the Earth has less water than around the appearance of life.)

This theory is likely to be true, so meteorites probably have brought a good part of the chemical elements most needed by living beings.

However, most of the pre-existing organic substances from meteorites must have decomposed and whatever has been preserved of them could not have had any significant role in the appearance of life here, because any living being would have needed a continuous supply with any molecules that it needed, otherwise it would have died immediately. Such a continuous supply could have been ensured only for molecules that were synthesized continuously in the local environment here, not for molecules arriving sporadically in meteorites and which would have been diluted afterwards over enormous areas, down to negligible concentrations.

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#79

Post by majkinetor »

HarHarVeryFunny wrote: post #18
0x000xca0xfe wrote: post #8

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 se…

I guess it depends on how you define life, and whether we'd even recognize it when we see it, assuming we're looking in the right places. I'd also imagine that any type of chemistry that harvests energy from the environment is liable to find itself as a food source at the bottom of the food chain now that earth is teeming with life. I think that self-replication, and ability to harvest chemicals and energy from the e…

> I think that self-replication, and ability to harvest chemicals and energy from the environment to make more of what you're built of, is the point of complexification of chemistry that is best considered as the most primitive form of life

Once there are forms that harvest and self-replicate, however, its expectable that there will be forms that delegate those features to others, like viruses. Cellular machinery that is required to implement those feature is not free, so parasitic forms would have survival advantage.

Re: Ryugu asteroid samples contain all DNA and RNA building blocks

#80

Post by general_reveal »

lazide wrote: post #37
BinaryAsteroid wrote: post #32

Earlier quoted context omitted.

The timing of the delivery is what's important here. These building blocks, organic matter, and water would have been depleted in the proto-Earth due to Solar irradiation. There needs to be some mechanism that delivers these ingredients from the outer Solar System. Bombardment by smaller rocks makes the most sense, and was likely triggered by the migration of Giant Planets, leading to a period of heavy bombardment (o…

Huh? Those smaller rocks would be even more irradiated, as they have no atmosphere? They’d also have to contend with re-entry.

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