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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

#141

Post by beowulfey »

lazide wrote: post #124
Supermancho wrote: post #109

Earlier quoted context omitted.

> it seems implausible at first glance that these things would develop or survive in open space rather than here. I don't think "organics developed in the vacuum of space" is implied. Survived? Well we have samples now confirming, if I'm understanding the basis for the discussion (the article).

We have some organic ‘building block’ compounds confirmed frozen on some asteroids. But what we don’t have is any examples of them surviving re-entry. We also have a massive amount of those same compounds already here on the planet. Causality is… tenuous. But not impossible.

Causality was not the point. The point was to refute the seeding hypothesis, and because they found those molecules, the effort to falsify the hypothesis failed. Now we can move on to the next attempt to refute, which, as you say, might be to study whether molecules can survive conditions of reentry.

Experiments do not tell us that something IS a certain way; only the ways it is not.

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

#142

Post by XorNot »

adrian_b wrote: post #129
asdff wrote: post #111

Earlier quoted context omitted.

>However, any RNA-based catalyst could have appeared only at a later time after the establishment of RNA self-replication. RNA by virtue of its biochemistry is capable of self replication already. Sequence affinity alone is sufficient to drive structure formation. But without a template, structure can also form on its own (example of an open access paper exploring one such mechanism under certain conditions, 1). This…

Nope. RNA is not capable of self replication. RNA by virtue of its biochemistry is only capable to be used as a template for replication, but the copying of the template must be done by a different molecular machinery. If you put almost any RNA molecule in a jar together with monomers, you can wait until the end of time to see its replication. Normally, RNA can be replicated only by a special enzyme, a RNA-dependent…

> RNA is not capable of self replication. RNA by virtue of its biochemistry is only capable to be used as a template for replication

RNA molecules which can synthesize others have been produced in a lab.[1,2] Your claim is not only totally unsupported, it's been experimentally disproven.

Laboratory RNA production can be done with regular batch chemistry - no enzymes involved, so on a long enough time span heat and mixing would be able to polymerase candidates out of the primordial soup.

RNA self-affinity is well documented, double-stranded RNA viruses exist[2] so stable conformational arrangements of RNA are not only experimentally proven but so viable they exist in todays much more enzymatically hostile world.

The relative difficulty of the structure persisting is a point in favor it is as a replication medium, since if RNA could tightly bind RNA then templating new strands would inactivate it.

[1] https://www.science.org/doi/10.1126/science.1060786

[2] https://www.pnas.org/doi/full/10.1073/pnas.1610103113

[3] https://en.wikipedia.org/wiki/Double-stranded_RNA

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

#143

Post by jibal »

qsera wrote: post #99
kmaitreys wrote: post #52

Earlier quoted context omitted.

Multi-worlds is not really relevant here. You are just asking the question how the building blocks of life form in the Universe and how can they reach a planet like ours.

I mean, Multi worlds is the only way this impossibly random event can occur on its own.

Sorry, but nothing you have said here is true or makes sense. Multi worlds are universes, not worlds within our universe. The multiworld interpretation is one of several interpretations of quantum mechanics of the exact same evidence--one or the other interpretation being "true" has no empirical implications. And it is an interpretation of quantum mechanics, which has nothing to do with the distribution of nucleotides. And it's incoherent to call an observed event "impossible". You seem to mean that you think that it is highly unlikely, but offer no reason to think so ... nor for the bizarre claim that "Multi worlds is the only way". I suspect that you are mixing up a very confused understanding of "Multi worlds" with some version of the anthropic principle. But the anthropic principle is an a posteriori explanation of an a priori unlikely occurrence, it's not a "way" for something to happen.

I won't comment further unless you offer a convincing proof of your assertion.

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

#144

Post by XorNot »

twodave wrote: post #105
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 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…

Which is underplaying what "trying" means in this context: we live on a planet with a lot of life - life which by definition was a superior competitor to the much simpler life it supplanted. The world, even enzymes from our skin, are unimaginably hostile to most candidates for simpler primordial lifeforms.

The reason showing abiogenesis is hard is because (1) everything in the biosphere would kill and eat the result and (2) the one thing it had going for it was time - millions of years of random diffusion with nothing else busy executing a grey goo type attack on all the available resources.

Frankly if someone gets abiogenesis to work in a lab environment within a single human lifetime, it wouldn't just be evidence for how it might've happened in Earth's past it would more or less set the parameters for how much life there must be in the universe everywhere because a mere 50 to 100 years to kickstart anything would be insane.

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

#145

Post by Citizen_Lame »

stouset wrote: post #114
dylan604 wrote: post #98

Earlier quoted context omitted.

So you survived re-entry. Now, you get to survive impact. Seems like the energy released would also be damaging

Most asteroids have slowed to terminal velocity by the time they impact. It’s not nothing, but it’s mostly going to be relevant to physical processes and not chemical ones. You might consider that scientists advanced enough in their field to be launching missions to retrieve dust from asteroids are actually aware of basic facts relevant to their field of study.

Quality of comments massively dropped on the HN. It feels like Facebook now.

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

#147

Post by pfdietz »

asdff wrote: post #121
pfdietz wrote: post #71

Earlier quoted context omitted.

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

https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002...

That's not replication, that's polymerization. There's nothing template-directed about it, and as far as I can tell the experiment depends on pure initial conditions (the guanosine monophosphate is not mixed with a plethora of other chemicals that could copolymerize with it.)

That purity is the kind of artificiality I was talking about. A bad habit of OoL research is to show that some chemical shows up in trace amounts, then starting the next stage of experiments with a pure batch of that chemical. Robert Shapiro in his 1986 book "Origins" had some very biting things to say about this (the book is not nice to creationists either, btw.)

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

#148

Post by pfdietz »

adrian_b wrote: post #135
pfdietz wrote: post #112

Earlier quoted context omitted.

People make the inference that "early occurence of life" implies "life must be easy to start". But that inference requires the assumption that the chance of OoL (origin of life) remains mostly constant with time. An alternative would be that the conditions under which life could arise are transient, so life either starts early or not at all. We don't know enough about OoL to rule this out. Some chemicals that might b…

It is indeed possible that in the early Solar System, before the short-lived radioactive elements completely decayed, there were some asteroids with good conditions for the appearance of life. However, I would not describe those as small. The majority of the interplanetary bodies that orbit the Sun and which fall from time to time on Earth as meteorites are far too small to have ever had conditions for the appearance…

> However, I would not describe those as small. The majority of the interplanetary bodies that orbit the Sun and which fall from time to time on Earth as meteorites are far too small to have ever had conditions for the appearance of life.

So what? The meteorites that fall to Earth were not that size for their entire existence. They are fragments of larger bodies that have collided over the billions of years. Iron meteorites, for example, are remnants of the cores of larger bodies that were big enough to undergo melting and differentiation in the early solar system.

Moreover, "not all places are suitable for OoL, therefore no places are suitable for OoL" would be a non sequitur, so I don't see how what you're trying to say there leads anywhere useful.

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

#149

Post by kakacik »

pfdietz wrote: post #33
ceejayoz wrote: post #17

Earlier quoted context omitted.

> All it means is you can say "if life is rare, it's not because these specific small chemicals can't be produced". This is absolutely a good finding to have in your pocket.

"Good"? Ok, if it makes you feel better. But scientifically, it doesn't do much.

Whats your problem with this topic? Highly confronting posts about nothing. Iterative approach to science seems foreign here.

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

#150

Post by kakacik »

nikolay wrote: post #107

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!

So what? We are not really experienced in judging how chemical processes work across (a half of) billion year timespan. Or how can intense lighting and volcanic activity across similar timespans affect the probabilities of outcomes. And so on
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