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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."
I think they mean the carbon 13 to carbon 12 ratio is not "earth normal".
Reading TA would not have helped... it is still a mystery. It can only mean an isotope. The funny thing is that this 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.
IANAB (I am not a biologist), but I think that when scientists talk about "life coming from space" they mean "complex carbon compounds that could, given the circumstances, combine into self-replicating structures that would, some time later, become living organisms". In other words, the secret ingredient needed for life to appear on Earth.
But thinking "ZOMG there were living cells in the meteorite!" is just crossing the line.
i know i sound like a jerk, but what else do you think they would be talking about?
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.
The X files wasn't a documentary.
http://michaelsmith.id.au
You don't mean skeptics here. They are the good guys and they should challenge the findings.
You mean fundamentalist nut jobs that ignore evidence and argue out of their nether regions
a meteorite that landed in Australia...
landed you say? fascinating indeed.
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
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Organic material coming here on comets and meteorites is perfectly plausible. But life coming from outside the solar system seems to be quite unlikely.
There was some paper released last year showing that gene degradation when exposed to cosmic rays happens at an astonishing rate. When compared to how long it would take a piece of rock to travel from even the nearest star, it just looks to be implausible at best. Not only that, it would assume that the life would be able to survive the impact and either be compatible, or adapt from the rock/ice quickly to the earth.
Even if panspermia was a viable idea, it would only say something about where life arose. It doesn't answer the question of how life arose. But if it arose here, then it would be easier to find the how. If life arose elsewhere, then we wouldn't know
To many people the term 'skeptic' has come to mean someone who disagrees, logic and training don't come into it. However skepticisim is an integral part of science and every scientist worth their salt practices skepticisim on their OWN ideas before using it to attack the ideas of others. The term the GP was looking for is 'psuedo-skeptics', ie: a person who fails to be skeptical of what they themselves 'know' and does not entertain criticisim. The worst kind of 'skeptic' is a denier, ie: someone who is willfully ignorant.
... when awesome technological powers are in the hands of a very few, and no one representing the public interest can even grasp the issues; when the people have lost the ability to set their own agendas or knowledgeably question those in authority; when clutching our crystals and nervously consulting our horoscopes, our critical faculties in decline, unable to distinguish between what feels good and what's true, we slide, almost without noticing, back into superstitions and darkness."
Personally I am skeptical that any individual fits neatly into one category althogh I do agree fundamentalist nut jobs are an 'edge case'.
Carl Sagan's book on the subject is a great read and can speak for itself...
"Science is more than a body of knowledge; it is a way of thinking. I have a foreboding of an America in my children's or grand children's time
OTOH, a skeptic might argue that Sagan's forboding is, and always has been, the status-quo.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
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.
A polar bear is a cartesian bear after a coordinate transform.
the so called hostile temperatures on earth are nothing compared to the hostility of the environment in space.
massive radiation, shockwaves, coronal mass ejections, MASSIVE extremes of heat and cold, and very importantly, the tendency for water to remain in a vaporous or solid form rather than liquid because of the lack of pressure.
Not to say the first dna fragments, amino acids, or single celled life forms could not have come from space, but they had to develop on some body with enough gravity and atmospheric pressure to host some liquid water water.
This characteristic need for liquid water is too fundamental to have simply arisen after this life came to earth.
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they don't have to prove evolution.
overwhelming evidence has already been recorded on the micro and macro level.
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Whole microbes surviving in an airless, nutrientless, radiation-saturated enviornment is not unprecedented. The Apollo 12 crew found scores of living streptococcus mitus doing just fine on the Surveyor probes on the moon, which had been there for three years. While its doubtful whole cells came here and populated the planet, it also seems unlikely that the Earth alone provided all the ingredients.
I find it really, really disturbing that people labeled "scientist" continue to have a go at the outer space theories. Out of all PhD:s in science I have met and the topic has been brought up I have never met anyone who believed in actual life coming from outer space, or that extraterrestrial material in fact would have been needed on a primordial Earth in order to create life. That a US president was blatantly fooled into promoting that childish Mars rock theory from a decade ago still hurts my mind. Think Occam's Razor. Dig where you stand. Don't overdo it, son.
"Honey....your 9th x 10e47 cousin from Rigel is here! He brought the wives and kids. You know they don't like my cooking, so bring home some KFC"
Blegh, can you imagine the politics?
"Remember not to get Taco Bell because Rigellians worship a taco-shaped diety and it would be highly offensive to them... and do remember they have the technology to vaporize this continent with their wristwatches "
Seven puppies were harmed during the making of this post.
I wonder how simple molecules these would be treated as by a chemist. That's the big question to me. Are they so simple that it's quite likely they'll both have appeared on Earth and in space? Because, in that case, this isn't really as impressive as it may seem. Just because they're used in DNA/RNA doesn't imply they're complex alone.
:)
Uracil: http://en.wikipedia.org/wiki/Uracil
Xanthine: http://en.wikipedia.org/wiki/Xanthine
As an amateur, they don't look too complex to me, but hey, what do I know...
Beware: In C++, your friends can see your privates!
Yeah, I tend to think that evidence like this of organic compounds in meteorites is looked at more as proof that they are formed (and distributed) routinely throughout the universe, rather than trying to say that this was the mechanism by which they arose on Earth. This has pretty serious implications for things like the Drake Equation, or at least the likelihood of planets with habitable climates having access to the materials necessary for life to come about.
Recursive: Adj. See Recursive.
The atmosphere of Venus is considerably more dense than Earth's. As is Saturn's, Jupiter's and Uranus'. The importance of the density of atmosphere is irrelevant. For every atmospheric density there is an insertion vector where a lifeform resident on a meteor could be brushed off and float gently down.
What's important is the hospitality to life and the flexibility of life. We know that life is ridiculously flexible. There are forms of life in volcanic vents on Earth that would find Venus a paradise beyond imagining. In the past most of the planets in our solar system have been hospitable to some form of life found on our planet. It's reasonable to expect that there is some form of life on Earth that might find the crushing pressures of a gas giant inviting. For all we know the Great Red Spots are actually a life form of some kind.
In short, "life finds a way." We can take it as a given that our solar system has been so thoroughly polluted by life that everywhere it could take root it did. It's an open question whether it first took root in our solar system on Earth or elsewhere. I'm for Mars, but that's just an opinion. We're infested with life and with this meteorite we have evidence we're not the only solar system to be so infested. It follows that life is as common elsewhere in our galaxy as it is here. That means that the panspermia theory is at least partly true -- in the one example that we know of it's possible that some form of life will cross the stars. In regards to life if it can be done, it will be done. Therefore all the planets in our galaxy that can support life similar to ours have life. This is a big discovery.
When we get to the planets around distant stars we will find life that we understand. Let's go!
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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
http://en.wikipedia.org/wiki/Myth_of_Streptococcus_mitis_on_the_moon
We are Dead Stars looking back Up at the Sky
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.
"The greatest obstacle to discovery is not ignorance - it is the illusion of knowledge." - Daniel Boorstin
Well, it would offer a solution to the Fermi Paradox, i.e. if even one civilization set out to colonize the galaxy they could do so in a surprisingly few millions of years - so where are they?
Answer: Aaahh-chooh!!! There's Waldo!
Unless someone finds an end-run around Relativity, interstellar travel is going to be slow, so the main motive behind colonization would be to spread your genome - and if you want self-replicating machines, why re-invent the wheel? (See Titan by Stephen Baxter).
Of course, the converse is that the Fermi Paradox arises from the false assumption that advanced civilizations would behave like "bacteria with spaceships" and "go exponential" (Greg Egan, Diaspora).
PS: its fun and stimulating to speculate about such things provided you don't get them confused with scientific truth. Hence I cite SF novels rather than papers in Nature!
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