Genetic Building Blocks Found In Meteorite

FiReaNGeL writes to tell us scientists have confirmed that the components of genetic material could have originated in a place other than Earth. A recently published report explains how uracil and xanthine, two basic biological compounds, were found within a meteorite that landed in Australia. From Imperial College London: "They tested the meteorite material to determine whether the molecules came from the solar system or were a result of contamination when the meteorite landed on Earth. The analysis shows that the nucleobases contain a heavy form of carbon which could only have been formed in space. Materials formed on Earth consist of a lighter variety of carbon."

Re:What does that mean?

[Psychotria]

Reading TA would not have helped... it is still a mystery. It can only mean an isotope. The funny thing is that this [nature.com] article in Nature refers to heavy carbon as well. Heavy carbon that occured on earth. So, TFA this slashdot story is talking about is very vague and raises more questions than it answers.

Re:What does that mean?

[Beryllium Sphere(tm)]

Exactly. The popular writeup was terrible, but the actual paper explains that the ratio of C-13 to C-12 was 44.5% higher than earth-normal for the uracil and 37.7% higher for the xanthine.

Let's go over the line...

[symbolset]

But thinking "ZOMG there were living cells in the meteorite!" is just crossing the line.

Of course that would be silly. The living cells trapped inside the meteorite would have been baked into the material these researchers found. It's the light fluffy life forms on the exterior of the meteorite that would have been brushed off the surface of the meteorite on first contact with the atmosphere and drift gently down to the nutrient rich sea that covers most of our planet. There these hypothetic organisms would breed and diversify until they filled every sea, covered every continent and dwelled deep within the crust.

Eventually a form would evolve, such as a lichen or mold, that bred with colonies so small and potentially electrostatically charged by sunlight that they might rise to the highest reaches of the atmosphere - to be scooped up by passing meteors on their way to the unknown depths of space. Perhaps they might by a fluke of trajectory be thrown clear of the solar system altogether. Frozen in the cold of space these breeding colonies might last millions of years. The vast majority of these would wander 'twixt the stars eternally, finding no place they might rest or fall on a hostile environment and die. Given enough of them, though -- perhaps millions an hour for a billion years -- some few might land someplace they can start anew.

It's called panspermia [wikipedia.org]

Re:What does that mean?

[Anonymous Coward]

I suggest very strongly you read Sagan's 'The Demon Haunted World'. This 'evidence' is easily explained without resorting to 'ET' intelligence.

Why not?

[Moraelin]

Actually, I'd argue that it's both rather expectable _and_ at the same time meaningless.

The basic nucleotides and aminoacids can be formed rather quickly even in a retort in the lab, given the right conditions (similar to those of primal Earth). But even that is somewhat misleading: really they just need a lot of energy. Carbon and nitrogen just tend to do that, and we're talking simple building blocks, not a whole ribosome.

What took an awfully long time is those actually becoming _life_. I.e., those assembling, by sheer chance, in a self-replicating configuration.

Really, there's nothing special about finding isolated aminoacids or nucleotides. They're not yet life, they're the Lego blocks that actual life is made of. Aminoacids are not a miracle by themselves, but in the fact that they can be assembled in proteins that can react with any chemical you wish. Or produce another chemical that reacts with it. Including assemble other proteins. Nucleotides are even more meaningless by themselves. They can form a RNA strand, which is what the first and simplest life used. But the RNA strand does nothing whatsoever by itself. It needs some proteins that (A) replicate it, and (B) translate it to other proteins, before it can count as life.

The "miracle" isn't when you have aminoacids and nucleotides. It's when you have at least some kind of RNA replicase and some kind of a ribosome.

So basically "ZOMG, we found a nucleotide on a meteorite" is simultaneously:

1. not that surprising, since really they form anywhere.

2. rather meaningless for life on Earth, in that we have plenty of proof that they formed withing minutes on Earth too, with the conditions back then. So a couple of those molecules maybe came on a meteorite too. Big deal, compared to the whole billions of tons of them forming right here.

3. rather unlikely as a source of life on Earth. Sooner or later those molecules break down. They don't last for ever. And we're not talking self-replicating life, but some building blocks which still needed to combine into a configuration that can be called "life", by sheer chance. That means lots and lots of them, and lots and lots of time. It's kinda absurd to assume that meteorites kept bringing billions of tons of them, for billions of years, until they finally recombined into some kind of ribosome.

4. it at best brings some extra insight into it all. If they're as easy to form as to even exist in meteorites, well, it just makes it easier to believe that we had a lot here too. In fact, maybe we had them earlier than we thought, as Earth itself formed out of dust which coalesced into meteorite, which coalesced into a planet. The last one captured was the one that ejected a chunk of Earth and created the Moon. So maybe we had some building blocks before Earth even formed. It also means we can expect almost any planet anywhere to have _some_ of the building blocks, and evolve life, if the conditions and timing are right.

But again, not an awful lot of insight that we didn't already have anyway.

Re:Logical conclusion?

[plasmacutter]

they don't have to prove evolution.

overwhelming evidence has already been recorded on the micro and macro level.

Ever the optimistic

[Tarlus]

...scientists have confirmed that the components of genetic material could have originated in a place other than Earth.

Let me fix that.

...scientists have confirmed that the components of genetic material could have existed in a place other than Earth.

Re:Wow.

[Anonymous Coward]

But "complex carbon compounds" would have formed naturally here on early earth anyway (this has been replicated in the lab by simulating those conditions). That part is inevitable.

The more interesting part is the emergence of circular chain reactions, self-replication and life.

Streptococcus on Surveyer accident

[wooferhound]

Streptococcus microbes found on the Surveyor was an accidental contamination after the parts were returned to the Earth.
http://www.kosmix.com/Health/Myth_of_Streptococcus_mitis_on_the_moon-Bacteria-Streptococcus_Pneumoniae-Bacteria-Streptococcus_Mitis/-od-definition_wiki_Myth__of__Streptococcus__mitis__on__the__moon-s [kosmix.com]
http://en.wikipedia.org/wiki/Myth_of_Streptococcus_mitis_on_the_moon [wikipedia.org]

Re:Ever the optimistic

[eclectic4]

No, it was right the first time. That is, unless, you are suggesting that this meteorite is made of Earth material, which would be a pretty neat trick considering "the nucleobases contain a heavy form of carbon which could only have been formed in space". Not to mention the whole "meteors usually not "originating" from Earth" thing...

Seriously, if you have further evidence, please expound. Otherwise your post makes no sense.

Re:Why not?

[Eternauta3k]

Nucleotides are even more meaningless by themselves. They can form a RNA strand, which is what the first and simplest life used. But the RNA strand does nothing whatsoever by itself.

Oh really? [wikipedia.org]

Re:Atmospheric properties

[RockDoctor]

We know that life is ridiculously flexible.

It's more flexible than most people think, but it does have real constraints. The presence of liquid water being one - even if under pressure ; moderate temperatures being another - unless the record has been raised in the last few years, the highest temperature at which an organism has been observed to reproduce is in the order of 120degC, and that hasn't changed greatly in the last decade. Getting up to 140 or even 150degC may be credible, but 200degC is being very optimistic - no complex molecules are known that are stable to such temperatures, particularly in wet conditions.

There are forms of life in volcanic vents on Earth that would find Venus a paradise beyond imagining.

I suspect that you refer to the organisms that inhabit "black smoker" hydrothermal vents. While these are associated with volcanic systems, and the imagery used on the likes of "Discovery Channel" implies that they're found with flowing lava, boiling lava fountains, etc, this impression is incorrect. The systems are called "hydrothermal" because they involve hot water, but the pressures involved prevent the water from boiling. Underground the water is often supercritical, but where the hydrothermal vent water mixes with seawater, the temperature plummets rapidly. This is the region where the interesting chemoautotrophic communities are found, powered by gradients of temperature, pH, redox potential, and (often) sulphide concentration. This is also where the interesting high-temperature bugs are found. And they don't seem able to get up above about 120degC, as noted above. with the 2black smoker" systems, you're back to needing the presence of liquid water.

The ppH2O (partial pressure of water) in the atmosphere of Venus is too low to permit it's presence on the surface of Venus. The pH is quite horrible too, but that's not likely to be unsurvivable.

In the past most of the planets in our solar system have been hospitable to some form of life found on our planet.

Earth is definitely hospitable, Mars possibly has been, Venus almost certainly never could have been, Mercury never; the gas giants have too different a chemistry to assess readily (is life possible based on liquid ammonia? You'd be hard put to find a chemist who'd say it was impossible, but we've no direct evidence of metabolism-like systems in liquid ammonia); interesting things may be possible in the satellites of the gas giants, and it's certainly worth investigating, but there's no hard data.