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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 04/10/2009 : 05:46:14
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In the absence of actually having an alien in custody to experiment upon horribly, I can only ask, "Why not?"
The building blocks of life may be more than merely common in the cosmos. Humans and aliens could share a common genetic foundation.
That's the tantalizing implication of a pattern found in the formation of amino acids in meteorites, deep-sea hydrothermal vents, and simulations of primordial Earth. The pattern appears to follow basic thermodynamic laws, applicable throughout the known universe.
"This may implicate a universal structure of the first genetic codes anywhere," said astrophysicist Ralph Pudritz of McMaster University in Hamilton, Ontario.
There are exactly 20 standard amino acids — complex molecules that combine to form proteins, which carry out instructions specified by RNA and DNA, its double-stranded and self-replicating descendant.
Ten were synthesized in the famous 1953 Miller-Urey experiments, which modeled conditions believed to exist in Earth's early atmosphere and volcano-heated pools. Those 10 amino acids have also been found in meteorites, prompting debate over their role in sparking life on Earth and, perhaps, elsewhere.
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Interesting, no?
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist! 
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Edited by - filthy on 04/10/2009 05:47:18
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Simon
SFN Regular
USA
1992 Posts |
Posted - 04/10/2009 : 09:02:49 [Permalink]
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It is interesting but, really, panspermia theory has been around quite a while.
The reason why it is not the privileged theory is mostly that, as mentioned in the article, the same amino-acids would form readily under the primitive Earth condition. So they is little need for Panspermia.
The article does not mention nucleic acids which are currently considered a more likely candidate for the formation of prebiotic chemistry.
Nonetheless, it is always interesting and one of the reason why, when we discover alien life, I would not be excessively surprise if its biochemistry is relatively close from us... |
Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Carl Sagan - 1996 |
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Kil
Evil Skeptic
USA
13477 Posts |
Posted - 04/10/2009 : 09:53:08 [Permalink]
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Originally posted by Simon
It is interesting but, really, panspermia theory has been around quite a while.
The reason why it is not the privileged theory is mostly that, as mentioned in the article, the same amino-acids would form readily under the primitive Earth condition. So they is little need for Panspermia.
The article does not mention nucleic acids which are currently considered a more likely candidate for the formation of prebiotic chemistry.
Nonetheless, it is always interesting and one of the reason why, when we discover alien life, I would not be excessively surprise if its biochemistry is relatively close from us...
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Technicly, what's described in filthy's post is not really panspemia as I understand it. I thought that panspermia suggests that seeds of life, (and not simply the materials that comprise the building blocks of life) or bacteria some how made it to the Earth by means of comet or asteroid strikes or purposely "planted" by an alien intelligence.
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Uncertainty may make you uncomfortable. Certainty makes you ridiculous.
Why not question something for a change?
Genetic Literacy Project |
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Simon
SFN Regular
USA
1992 Posts |
Posted - 04/10/2009 : 10:06:57 [Permalink]
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| Well; the term panspermia refers to 'the seeds' of life. But you are right, as far as I know, these seeds could be living bacteria as well as prebiotic elements. |
Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Carl Sagan - 1996 |
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 04/10/2009 : 10:59:02 [Permalink]
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This is the hypothesis I've been entertaining ever since I took the Astrobiology class some eight years ago. Carbon being an abundant element, with such an astounding ability to form complex molecues, is the natural choice for life.
While silicon also shares a similar chemical property (the number of electrons in the outer shell being very important in what kind of molecues it can form) to carbon, the physical restraints placed upon it by the fact that the nucleus is more than twice its weight compared to carbon makes it unable to form the kind of "amino acids" as carbon can. The molecues gets unstable at so much lower temperatues it wouldn't function as a building block for life. |
Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3
"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse
Support American Troops in Iraq:
Send them unarmed civilians for target practice..
Collateralmurder. |
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 04/10/2009 : 11:30:04 [Permalink]
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What I got out of the article was not support for panspermia but rather a natural conformation of Miller/Urey. The amino acids they they synthesized in the lab are evidently quite common, leaving the others to come about under extraordinary circumstances. I speculate that those circumstances might be found in various volcanic events such as the mentioned hydrothermal vents and perhaps even in such places as the hot, acidic pools of Yellowstone, wherein bacteria already thrive.
Can't rule panspermia out, but I find it unlikely. I think that anywhere the right conditions exist, abiogenesis will occur. We are not yet sure of what those conditions are, but Darwin's "warm, little pond" was, I think, most likely a steaming hell-hole that only an extremophile could survive. If so, our earliest ancestors were noble indeed.
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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BigPapaSmurf
SFN Die Hard
3192 Posts |
Posted - 04/10/2009 : 11:52:56 [Permalink]
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| Panspermia is a natural seeding, Exogenesis is when its intentionally seeded by an intelligence. |
"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History
"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini |
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 04/10/2009 : 13:34:07 [Permalink]
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Earthly DNA is made up of just four nucleotides: Adenine, cytosine, guanine and thymine. Terrestrial RNA is also made of four nucleotides: Adenine, cytosine, guanine and uracil.
We don't -- at this point -- have any reason to think that an extraterrestrial DNA or RNA would use those same nucleotides. Other molecules could probably be substituted.
If, when we first find extraterrestrial life, we find it uses ACGT DNA and/or ACGU RNA, I think that would make it likely that either panspermia is pervasive in the Galaxy, or that there are underlying chemical reasons that those chemistries are superior for genetics.
Personally, I'd guess that neither DNA or RNA is going to be the only genetic material out there, but that when we do find DNA and RNA, they will use a different nucleotide mix more often than not.
That ten amino acids have been found in space, and that these ten are building blocks of life, doesn't amount to panspermia. In fact, I suspect that we'll be finding that those molecules can arise just about anywhere, and aren't much of a bottleneck problem for abiogenesis. Instead, their abundance is simply good indirect evidence that life can arise all over the place.
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
| Edited by - HalfMooner on 04/10/2009 15:19:12 |
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Machi4velli
SFN Regular
USA
854 Posts |
Posted - 04/10/2009 : 23:21:31 [Permalink]
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I was trying to reaffirm how carbon is formed and ran across this gem of science:
http://designanduniverse.com/articles/carbon.php |
"Truth does not change because it is, or is not, believed by a majority of the people."
-Giordano Bruno
"The greatest enemy of knowledge is not ignorance, but the illusion of knowledge."
-Stephen Hawking
"Seeking what is true is not seeking what is desirable"
-Albert Camus |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 04/10/2009 : 23:46:41 [Permalink]
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| Geeez, give a guy a little more warning! It's near-impossible to read the sarcasm with which you wrote the word "gem." I almost puked with the materialism-vs-miracles crap on that page. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Machi4velli
SFN Regular
USA
854 Posts |
Posted - 04/11/2009 : 00:55:13 [Permalink]
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| Almost conjures a gag reflex huh... The worst thing is that you can tell it is intentionally misleading. What other purpose could there possibly be for not using scientific notation in that context? |
"Truth does not change because it is, or is not, believed by a majority of the people."
-Giordano Bruno
"The greatest enemy of knowledge is not ignorance, but the illusion of knowledge."
-Stephen Hawking
"Seeking what is true is not seeking what is desirable"
-Albert Camus |
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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 04/11/2009 : 02:25:08 [Permalink]
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Same ol' thing writ large: Argumentum ad ignorantiam. He sees something that cannot be brewed up in his kitchen nor bought in a can from the supermarket and assigns it miracle status. Miracles by their very nature, are non-falsifiable and therefore unworthy of consideration until every other avenue if inquiry is exhausted including the examination of outright lies. A "gem" indeed of typical creationist drivel.
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 04/11/2009 : 23:10:15 [Permalink]
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Here's the paper, "A thermodynamic basis for prebiotic amino acid synthesis and the nature of the first genetic code" (PDF format) which is referenced by the OP.
Reading this really helped me to understand the argument, essentially that ten amino acids (the building blocks of proteins) are found pretty much universally, and in very predictable proportions which are based upon thermodynamics. Other amino acids, which do not occur in non-biotic situations, are believed to have been synthesized by life. The first life was probably made up of the "original" ten amino acids, and later evolved to make the others.
I missed the point somewhat in my earlier post. This paper really makes a substantial point that, wherever abiogenesis happens, the first genetic molecules probably were made up from these ten universally and thermodynamically determined amino acids. That may have set life everywhere on an early path based upon a similar basic biochemistry. It seems to me that since the first replicating molecules (perhaps something less than "life" and something more than simple biochemistry) logically were the simplest self-replicating molecules possible, the same molecules are likely to have arisen as the basis of life everywhere life "abiogenned."
Maybe we'll be able to barbecue and eat the first ET we find!
Here's the Abstract:| Of the twenty amino acids used in proteins, ten were formed in Miller's atmospheric discharge experiments. The two other major proposed sources of prebiotic amino acid synthesis include formation in hydrothermal vents and delivery to Earth via meteorites. We combine observational and experimental data of amino acid frequencies formed by these diverse mechanisms and show that, regardless of the source, these ten early amino acids can be ranked in order of decreasing abundance in prebiotic contexts. This order can be predicted by thermodynamics. The relative abundances of the early amino acids were most likely reflected in the composition of the first proteins at the time the genetic code originated. The remaining amino acids were incorporated into proteins after pathways for their biochemical synthesis evolved. This is consistent with theories of the evolution of the genetic code by stepwise addition of new amino acids. These are hints that key aspects of early biochemistry may be universal. |
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
| Edited by - HalfMooner on 04/11/2009 23:11:05 |
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 04/12/2009 : 04:28:52 [Permalink]
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Then, as though to deliberately baffle me, there's this article at Science Daily, "Cool Stars Have Different Mix Of Life-Forming Chemicals": ScienceDaily (Apr. 10, 2009) — Life on Earth is thought to have arisen from a hot soup of chemicals. Does this same soup exist on planets around other stars? A new study from NASA's Spitzer Space Telescope hints that planets around stars cooler than our sun might possess a different mix of potentially life-forming, or "prebiotic," chemicals.
Astronomers used Spitzer to look for a prebiotic chemical, called hydrogen cyanide, in the planet-forming material swirling around different types of stars. Hydrogen cyanide is a component of adenine, which is a basic element of DNA. DNA can be found in every living organism on Earth.
The researchers detected hydrogen cyanide molecules in disks circling yellow stars like our sun -- but found none around cooler and smaller stars, such as the reddish-colored "M-dwarfs" and "brown dwarfs" common throughout the universe.
"Prebiotic chemistry may unfold differently on planets around cool stars," said Ilaria Pascucci, lead author of the new study from Johns Hopkins University, Baltimore, Md. The study will appear in the April 10 issue of the Astrophysical Journal.
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[My emphasis.]
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
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Simon
SFN Regular
USA
1992 Posts |
Posted - 04/12/2009 : 08:06:03 [Permalink]
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| Fuck! Fuck! Fuck! That's cool! Skeeeeeee! |
Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Carl Sagan - 1996 |
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 04/12/2009 : 16:27:20 [Permalink]
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Here's the NASA/JPL article on the "cool stars, different mix" thing I mentioned in my last post.
Along with much the same wording as quoted above, the JPL article says: | They found that the cool stars, both the M-dwarf stars and brown dwarfs, showed no hydrogen cyanide at all, while 30 percent of the sun-like stars did. "Perhaps ultraviolet light, which is much stronger around the sun-like stars, may drive a higher production of the hydrogen cyanide," said Pascucci. |
Acetylene and hydrogen cyanide detected near cool vs. sun-like stars
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
| Edited by - HalfMooner on 04/12/2009 17:02:36 |
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Humans and aliens share DNA roots?
