Extraterrestrial Origins Of Life on Earth

The following was shown on UK national news yesterday evening.http://www.channel4.com/...+of+life+comes+from+stars/2286077(click on the 'Watch this report' link on the page to see the actual news broadcast)Claims very strong evidence for the extraterrestrial origins of life on Earth.Anybody have any more detail of the basis for this story?
Any thoughts?Edited by Straggler, : No reason given.Edited by Straggler, : No reason given.

Very interesting indeed.Along with Amino Acids forming in the interstellar medium we can now add nucleobases.I would offer caution, however, and not bow to the hyperbole the BBC seemed to be displaying.We’ve known for some time that organic molecules can spontaneously form and come to us from space. The addition of nucleobases to the list is interesting. It does not show strong evidence, however, of “extraterrestrial origins of life,” but of extraterrestrial origins of lifeless molecules. This lends nothing to the panspermia overtones in the BBC piece.I especially liked the “how did they get into the (meteor) in the first place” question posed at the end of the piece. Amino Acids in Space

Hi straggler.The Murchison meteorite and its chemistry are actually old news, but that doesn’t change its interesting features. It could have brought traces of life from Mars to Earth, but the evidence is slim and disputed.One point I wish to make that is relevant here concerns the necessity of a life-bearing planet to have an atmosphere. From what I know of such things, Mars does not have a life-bearing atmosphere because its magnetic properties were insufficient to make a shield against the solar winds, and any atmosphere it tried to form may have been blow away. Thomas Gold, a free-thinking astrophysicist, hypothesized that Earth may contain two biospheres: one at its surface, which includes our atmosphere, and one existing about 15 km below the surface. In his book, “The Deep Hot Biosphere,” he argues that life could exist in the crusts of planets even if they didn’t have atmospheres. The organisms surviving “the deep hot biosphere” would have adapted to tremendous heat and pressure. At first blush it seems ridiculous from what we know about organic molecules under sever heat and pressure, but Gold offers some interesting thoughts on the matter.My point here is that we assume that life popped out of some special organic soup on the surface of bio-friendly Earth. And we want so badly to believe that abiogenesis happened only here. But Gold offers fresh ideas on the matter that may be useful to those who think about alternative biospheres that have influenced the evolution of life on Earth.Thomas Gold's thinking suggests to me that an extraterrestrial origin of life is even more plausible. Humans are naturally geocentric about our planet's role in the universe, until some sort of Copernicus comes along to change our minds.”HM

I'd say that given the recent evidence on amino acids being formed in space, the chances that it was stardust that synthesized the amino acids that gave rise to life on earth is quite high.This model would help solve the problem of chirality very elegantly.

The trouble is that amino acids don't often survive impact. When Bada et al investigated this by studying the Tunguska impact site for alpha-amino-isobutyric acid - which is common in interstellar space but extremely rare on earth - they didn't find any. (Here, page 12 - couldn't find a link to the research itself, sorry).Some amino acids created in space probably do reach the Earth but it is extremely unlikely that they ever did so in anywhere near the concentrations that would be necessary to explain the origin of life.Edited by Mr Jack, : Correction

What makes you conclude this?BtW are you the same cat avatar Mr Jack I just saw on the RPGNet forums? If so I agree with you about supporting role playing in both systems, lol.

The link I gave in the post has some of it. I've just been studying this as part of an OU course. We can calculate reasonably well the mass of material that fell on the earth around 4.5-4 Ga ago, although the quantities of amino acids contained in this material is more open, it's certainly not large (or we'd be detecting it in modern meteorites in large amounts), and there is good reason to believe most of it is destroyed before reaching the Earth. The oceans on the other hand, are very large, sticking the numbers (some of them guessed at) together you find that the chances of just two amino acids coming into contact mean that it would happen once every 10,000 to 100,000 years. That's simply not enough to account for the origin of life.I find hydrothermal vents a much more likely source of organic compounds needed to form life; bubble theory also seems interesting. Aye, that's me.

I had to look up chirality.
Why is it a problem and how do non-terrestrial factors help solve this problem?

Actually not the BBC but Channel 4. Another of the main terrestrial channels here in the UK with generally highly regarded news and current affairs output.So how likley is it that life as we know it did originate in space?

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The trouble is that amino acids don't often survive impact. When Bada et al investigated this by studying the Tunguska impact site for alpha-amino-isobutyric acid - which is common in interstellar space but extremely rare on earth - they didn't find any. (Here, page 12 - couldn't find a link to the research itself, sorry).

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Some amino acids created in space probably do reach the Earth but it is extremely unlikely that they ever did so in anywhere near the concentrations that would be necessary to explain the origin of life.

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I was referring to interstellar dust, not to asteroids.

Chirality suggests to me a single origin of life, rather than a multi-regional outbreak. But it suggests nothing about where that single origin occurred. If it happened extra-terrestrially and migrated to Earth, then we are caught by Mr Jack's assertion that organic molecules with chirality couldn't survive a panspermatic impact.On the other hand, a rare survival can't be ruled out, given what little we know about abiogenesis.”HM

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Chirality suggests to me a single origin of life, rather than a multi-regional outbreak. But it suggests nothing about where that single origin occurred. If it happened extra-terrestrially and migrated to Earth, then we are caught by Mr Jack's assertion that organic molecules with chirality couldn't survive a panspermatic impact.

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On the other hand, a rare survival can't be ruled out, given what little we know about abiogenesis.

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”HM

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Life as we know it uses only left-handed amino acids. If you had a bunch of right-handed amino acids tossed into the mix it'd be much, much, much harder for proteins made from purely left-handed amino acids to arise. So a primordial earth couldn't have a collection of amino acids that was a decent mixture of left and right-handed amino acids.Also, why in the world are people bringing up asteroid impacts? Not everything that falls to the earth are large, solid masses. The most likely explanation is an accretion of interstellar dust earlier in Earth's history, when planets were still mopping up remaining residues.

Interstellar dust does not fall in sufficient quantities to create a high enough concentration to acount for the origin of life.

Doesn't Dawkins or didn't he speculate on alien seeding of earth as possibly legitimate?

You're probably thinking of the segment of "Expelled" where Dawkins discusses the possibility of extra-terrestrial origins as a hypothetical. It's speculation, but nothing that Dawkins takes seriously as a real possibility.

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Toward the end of his interview with me, Stein asked whether I could think of any circumstances whatsoever under which intelligent design might have occurred. It's the kind of challenge I relish, and I set myself the task of imagining the most plausible scenario I could. I wanted to give ID its best shot, however poor that best shot might be. I must have been feeling magnanimous that day, because I was aware that the leading advocates of Intelligent Design are very fond of protesting that they are not talking about God as the designer, but about some unnamed and unspecified intelligence, which might even be an alien from another planet. Indeed, this is the only way they differentiate themselves from fundamentalist creationists, and they do it only when they need to, in order to weasel their way around church/state separation laws. So, bending over backwards to accommodate the IDiots ("oh NOOOOO, of course we aren't talking about God, this is SCIENCE") and bending over backwards to make the best case I could for intelligent design, I constructed a science fiction scenario

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From here Page not found | Richard Dawkins Foundation for Reason and ScienceI don't think he gives any credence to the idea and Ben Stein and co. are not being particularly honest in presenting the clip as such.Edited by Granny Magda, : Added link to quote source.

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