NASA finds proof that amino acid components in meteorites originate in space.
This is exciting news. NASA-funded researchers have evidence that some building blocks of DNA, the molecule that carries the genetic instructions for life, found in meteorites were likely created in space. The research gives support to the theory that a “kit” of ready-made parts created in space and delivered to Earth by meteorite and comet impacts assisted the origin of life. We may all be immigrants on Earth.
By Bill Steigerwald
NASA’s Goddard Space Flight Center, Greenbelt, Md.
NASA-funded researchers have evidence that some building blocks of DNA, the molecule that carries the genetic instructions for life, found in meteorites were likely created in space. The research gives support to the theory that a “kit” of ready-made parts created in space and delivered to Earth by meteorite and comet impacts assisted the origin of life.
“People have been discovering components of DNA in meteorites since the 1960’s, but researchers were unsure whether they were really created in space or if instead they came from contamination by terrestrial life,” said Dr. Michael Callahan of NASA’s Goddard Space Flight Center, Greenbelt, Md. “For the first time, we have three lines of evidence that together give us confidence these DNA building blocks actually were created in space.” Callahan is lead author of a paper on the discovery appearing in Proceedings of the National Academy of Sciences of the United States of America.
The discovery adds to a growing body of evidence that the chemistry inside asteroids and comets is capable of making building blocks of essential biological molecules.
For example, previously, these scientists at the Goddard Astrobiology Analytical Laboratory have found amino acids in samples of comet Wild 2 from NASA’s Stardust mission, and in various carbon-rich meteorites. Amino acids are used to make proteins, the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions.
In the new work, the Goddard team ground up samples of twelve carbon-rich meteorites, nine of which were recovered from Antarctica. They extracted each sample with a solution of formic acid and ran them through a liquid chromatograph, an instrument that separates a mixture of compounds. They further analyzed the samples with a mass spectrometer, which helps determine the chemical structure of compounds.
The team found adenine and guanine, which are components of DNA called nucleobases, as well as hypoxanthine and xanthine. DNA resembles a spiral ladder; adenine and guanine connect with two other nucleobases to form the rungs of the ladder. They are part of the code that tells the cellular machinery which proteins to make. Hypoxanthine and xanthine are not found in DNA, but are used in other biological processes.
Also, in two of the meteorites, the team discovered for the first time trace amounts of three molecules related to nucleobases: purine, 2,6-diaminopurine, and 6,8-diaminopurine; the latter two almost never used in biology. These compounds have the same core molecule as nucleobases but with a structure added or removed.
It’s these nucleobase-related molecules, called nucleobase analogs, which provide the first piece of evidence that the compounds in the meteorites came from space and not terrestrial contamination. “You would not expect to see these nucleobase analogs if contamination from terrestrial life was the source, because they’re not used in biology, aside from one report of 2,6-diaminopurine occurring in a virus (cyanophage S-2L),” said Callahan. “However, if asteroids are behaving like chemical ‘factories’ cranking out prebiotic material, you would expect them to produce many variants of nucleobases, not just the biological ones, due to the wide variety of ingredients and conditions in each asteroid.”
The second piece of evidence involved research to further rule out the possibility of terrestrial contamination as a source of these molecules. The team also analyzed an eight-kilogram (17.64-pound) sample of ice from Antarctica, where most of the meteorites in the study were found, with the same methods used on the meteorites. The amounts of the two nucleobases, plus hypoxanthine and xanthine, found in the ice were much lower — parts per trillion — than in the meteorites, where they were generally present at several parts per billion. More significantly, none of the nucleobase analogs were detected in the ice sample. One of the meteorites with nucleobase analog molecules fell in Australia, and the team also analyzed a soil sample collected near the fall site. As with the ice sample, the soil sample had none of the nucleobase analog molecules present in the meteorite.
Thirdly, the team found these nucleobases — both the biological and non-biological ones — were produced in a completely non-biological reaction. “In the lab, an identical suite of nucleobases and nucleobase analogs were generated in non-biological chemical reactions containing hydrogen cyanide, ammonia, and water. This provides a plausible mechanism for their synthesis in the asteroid parent bodies, and supports the notion that they are extraterrestrial,” says Callahan.
“In fact, there seems to be a ‘goldilocks’ class of meteorite, the so-called CM2 meteorites, where conditions are just right to make more of these molecules,” adds Callahan.
The team includes Callahan and Drs. Jennifer C. Stern, Daniel P. Glavin, and Jason P. Dworkin of NASA Goddard’s Astrobiology Analytical Laboratory; Ms. Karen E. Smith and Dr. Christopher H. House of Pennsylvania State University, University Park, Pa.; Dr. H. James Cleaves II of the Carnegie Institution of Washington, Washington, DC; and Dr. Josef Ruzicka of Thermo Fisher Scientific, Somerset, N.J. The research was funded by the NASA Astrobiology Institute, the Goddard Center for Astrobiology, the NASA Astrobiology: Exobiology and Evolutionary Biology Program, and the NASA Postdoctoral Program.
Related Link
› Related videos from NASA Goddard’s Scientific Visualization Studio
George E Smith writes:
“Well ‘The Big Bang’ is simply a possible model that appears to explain certain Astronomical observations. The “evidence” supporting such a model supports nothing additional; especially some ‘big banger’, which is every bit as conjectural as is ‘The Big Bang.’”
George, I encourage you to read the book “God and the Astronomers” by Robert Jastrow, the first head of Goddard Institute for Space Studies and a brilliant astronomer. The book describes not just the rise of the theory of the Big Bang but also observations which led to the theory being confirmed. Jastrow, an agnostic, also discusses very briefly the meaning of mass and energy coming into existence which did not exist before.
The following is a quote from Catholic Reverend Bill Zink: “Jastrow was not alone in evoking the supernatural to explain the beginning. Athough he found it personally ‘repugnant,’ General Relativity expert Arthur Eddington admitted the same when he said, ‘The beginning seems to present insuperable difficulties unless we agree to look on it as frankly supernatural.'” See http://frbill.stmarysmarne.org/2011/06/big-bang-theory.html
If you do not have ready access to the book, the website above does provide some interesting insights into Jastrow’s thought and conclusions.
I propose the WESTHAVER equation…
Unity = N = R* . fp . ne . fl . fi . fc . L . (fa . fb … . fn)
where:
N = the number of civilizations in our galaxy with which communication might be possible;
and
R* = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fℓ = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space.
and
(fa . fb … .fn) all number of special circumstantial variables which = sufficient a small enough number to offset the enormity of the universe to yield one special case for life, and all of which we have yet to discover their importance.
All evidence shows that human life is unique.
At 6:29 PM on 10 August, Gary Hladik had written:
Nope. It’s going to be:
“All right, Obama – or whatever in hell your name really is – you and your little ACORN buddies are all under arrest.”
God lives in space. So sure we were seeded with life from space.
TMJ says:
August 10, 2011 at 1:23 am
I can’t wait to see what Amino Acids in Meteorites has to say about this 🙂
LOL!
What do I have to say? Well, it’s about time NASA catches up with the rest of the science world that has known about this for years. Now if they can just get caught up with the real science of global warming……..
Reading this thread on what is purportedly a science blog, it is amusing how quickly the modest discovery of a few nucleobases in meteorites explodes into the realm of Belief—whether belief in natural, undirected origins or extra-natural directed ones. But Belief is really antithetical to Science, which is all about speculation, supposition, enquiry, hypothesis, theory—but never the rock-solid certainty that Belief implies. It is odd how uncomfortable people are with the simple assertion that, “We don’t know.”
But that’s the impetus behind the whole endeavor of Science: we don’t know, so let’s try to find out. The proper attitude of the scientist is one of Wonder, not Belief, wonder at the all-eveloping mystery that surrounds us, despite all that we have learned in recent years, wonder at how little we really do know, wonder at the immensity of our ignorance itself.
Those little nucleobases are just a bit of a clue, another tiny piece of the gigantic picture-puzzle we face, in contemplating the nature and origin of the universe, of life, of ourselves. Almost all of the puzzle is blank. We don’t even know what the picture is supposed to look like. But it’s wonderful when we find another piece.
/Mr Lynn
Perseid meteor shower due tonight. Go outside. Look up.
Tucci78,
Thank you for the link to the article by Dr. Jeff Glassman. It was an interesting read, even if I do not agree with all of it.
I like this part:
3. A theory is a hypothesis with at least one nontrivial validating datum. Candidates:
• Relativity.
• Big Bang cosmology.
• Evolution.
However, he continues in a way which indicates he is not familiar with intelligent design. He writes:
Some familiar models fail even to be ranked because they are beyond science, usually for want of facts. Candidates:
• Creation science or notions of “intelligent design.”
• Astrology.
• Parapsychology.
• UFO-ology.
The problem, of course, is that intelligent design is very much aligned with Big Bang cosmology. In other words, it is grounded in science. Intelligent design does not lack for facts. Instead it has adequate facts to show the universe cannot have come existence with a Big Banger. In a similar fashion, life cannot have come into existence without a life-giver. Life simply does not come from non-life. It is beyond the realm of science to make any proclamations that it can. Life from non-life has never been observed. To believe that life can come from non-life is an act of faith which has never and will never be confirmed by observation. Such a belief is strictly non-scientific.
Oops. One line should have read:
“Instead it has adequate facts to show the universe cannot have come into existence without a Big Banger.”
If you have to resort to the supernatural (e.g. “god”) it simply means you don’t have enough information.
It means everything that happens in the middle is totally meaningless.
By that logic, there can’t have been a “life-giver”, for two reasons, 1) who gave that life-giver life? 2) the life-giver can’t make like from non-life (e.g. a man from clay, or out of thin air).
Again, if you have to resort to the supernatural, it means you don’t have enough information. How did life originate? I don’t know, and neither do you. But we can keep trying to find out instead of attributing it to an invisible sky daddy.
Jeff,
You write: “If you have to resort to the supernatural (e.g. “god”) it simply means you don’t have enough information.”
I disagree. In some cases one must resort to the supernatural simply because natural processes are not up to the task. The Big Bang is one example. Again, please read God and the Astronomers by Robert Jastrow. It is a fascinating story of an important episode in the history of science and the ending may be a bit of a surprise for you.
Isn’t it funny how we want to use the physical to determine the presence (or absence) of the spiritual. The physical (by definition) can be measured using physical instrumentation, whereas (of course) the spiritual can only be sensed spiritually. We may choose to infer the the spiritual from the physical, but we can never prove it. Pretty much why half the people in this blog want to use this to prove the presence of God and the other half want to do the opposite.
I would be very interested to know by what mechanism these chemicals formed and whether it is possible they could form without invoking life elsewhere – presumably goes to the question of whether they are left, right or both handed.
I think it is interesting to see some of the quotes by non-Christian and agnostic scientists regarding the Big Bang.
“Now we see how the astronomical evidence leads to a biblical view of the origin of the world. The details differ, but the essential elements in the astronomical and biblical accounts of Genesis are the same: the chain of events leading to man commenced sharply and suddenly at a definite moment in time, in a flash of light and energy” (Robert Jastrow, God and the Astronomers, p. 14).
Scientist George Smoot (who was the scientist who lead the team of scientists who first measured ripples in the cosmic background radiation) says: “There is no doubt that a parallel exists between the big bang as an event and the Christian notion of creation from nothing”. (quoted in Fred Heeren, Show me God, p. 139.)
Agnostic (or Atheist) non-Christian scientist Arthur Eddington states: “The beginning seems to present insuperable difficulties unless we agree to look on it as frankly supernatural”. (Arthur Eddington, The Expanding Universe, p. 178)
Speaking of the big bang, agnostic astronomer Robert Jastrow states: “That there are what I or anyone would call supernatural forces at work is now, I think, a scientifically proven fact.” (A scientist caught between two faiths: Interview with Robert Jastrow, Christianity Today, August 6, 1982).
Lots of other interesting quotes on origins can be found at http://www.veritas-ucsb.org/library/origins/quotes/universe.html
When you read these quotes, it seems all of the great scientists would not be shocked by the basic tenets of Intelligent Design. One has to wonder how Intelligent Design came to have a bad name when so many Nobel Prize winners have spoken in this way.
I disagree, Ron. If it seems like natural processes aren’t up to the task, then it means we don’t know enough about them, or there are some we haven’t discovered. We know from experimentation and observation that rain occurs not because we’ve satisfied the gods, but due to natural processes.
Jeff Alberts,
“If you have to resort to the supernatural (e.g. “god”) it simply means you don’t have enough information.”
Ya think??
So, tell me exactly how we have the information on how mass, energy, gravity, and all their properties came into being again? OK, tell us how the singularity got there and decided to expand really fast/explode??
OK. God it is.
George E. Smith
August 10, 2011 at 4:25 pm
###
I think you need to ask Dr. Drake regarding his equation and why he formulated it. There is no problem with it. It show just what it was intended to show, the futility of it all. The 10^-20, Is a number I pulled from a very dark place, that was tiny, yet larger then the actual number. That is why I said LESS THEN. As it is, 10^-20 is incredibly small. Do you have any idea how small it is? Its small enough to be zero.
George E. Smith
August 10, 2011 at 4:25 pm
###
And furthermore, depending on what you are doing, zero*inf is equal to some real number.
John B says:
August 10, 2011 at 3:33 pm
The bases are planar, there is no chirality. Double bonds take it out.
Good grief! Did some of you guys do anything useful today?
Jeff Alberts: “By that logic, there can’t have been a “life-giver”, for two reasons, 1) who gave that life-giver life? 2) the life-giver can’t make life from non-life (e.g. a man from clay, or out of thin air).”
Several issues with your comments, but the above one jumped out at me, because it is a non-sequitur. Are you saying that it is not possible life could be created in the lab one day? Or are you just having fun with Ron Cram’s words — perhaps he didn’t phrase it quite right, but I read his statement about life not coming from non-life as referring to a strictly naturalistic scenario.
Jeff Alberts says:
August 10, 2011 at 9:13 pm
It means everything that happens in the middle is totally meaningless.
Lol, Nietzsche would be proud! Indeed, let’s analyze the universe without a context of actual meaning. No wait, let’s not. It’s not really that important anyway, is it? Is there a lazier intellectual/logical position to hold?
Well let me keep a bit to more to the science. How exactly do we think was the first living cell formed? What came first, the chicken or the egg? This actually is a relevant scientific question. Scientists have been able to do modifications on existing cells and seeds by genetic engineering but no scientist has ever been able to produce a living cell or seed out of the (dead) atoms and molecules that they consist of. Namely, if you mix all the atoms and molecules that make up the first living biological cell or seed together, and you have the right conditions of temperature, light, concentration, electrical charge, radiation etc, then apparently you would still have to wait for millions and millions of years for a “chance reaction” to take place that would produce the first living cell. So, in fact no one has ever been able to make a “living” cell or seed synthetically from the dead molecules and atoms…
What I find interesting is that when man starts throwing nuclear bombs or plays around with nuclear energy the next generation (eggs) is misformed. yet when human life started, they all came perfect out of the formed eggs. I wonder, but seems to me Someone has the right formula to make (human) life.
That same Someone claims that there is yet a final big river to cross to get to eternal youth and eternal life and that only He can pass it (John 13&14) He promised to leave a simple bridge for us, it is called faith. It is your free ticket to Heaven. He gives it for free. I am puzzled why anyone would not hold on to that ticket – seeing that it costs you absolutely nothing…
The funny thing is, once you sign that ticket and hold on to it somehow it does start changing your life. Better be ready for a few unexpected adventures.
Tucci78 @11:50 a.m.
Interesting quotes. Unfortunately, the primary thing they demonstrate is that Ronald Bailey doesn’t know what he is talking about when it comes to the design argument. Kenneth Miller should know better, but he continues to obfuscate and misrepresent the design argument, even though he knows he is putting up a strawman.
BTW, just as a general comment on this thread, whether there are nucleotides (or amino acids for that matter) in meteorites is completely irrelevant to the question of whether life arose naturally or was designed.
We will likely not find out precisely how life began here on Earth. That would require building a time machine. However, inquiries into the origin of life are important because to make any progress and headway, we must challenge many of our long held, cherished assumptions and biases. By doing so, we will come to a deeper understanding of the world around us.
Nature is always more interesting than you can imagine. Our imagination is partly constrained by what we have discovered in our inquiries, imagination in a straitjacket. There are several currently unavoidable limitations that we have concerning the origin of life. The first is that we have the n=1 problem: we only have one example. The second is that life here is abundant. Life has transformed Earth so much that the primordial conditions from which life arose no longer exist. Nevertheless, we can build plausible models from studies in geology and astronomy. These models will change over time as we find out more of what is possible by observing what has happened in the distant past (geology) and what has happened elsewhere (astronomy/space exploration).
In recent years, several discoveries have loosened our imaginative straitjacket. Organisms have been found living in environments few thought could have supported life. Bacteria and Archaea have been found living in the rocks of the deepest, darkest mines; living in the rocks in Death Valley; living in the rocks of the walls of the dry valleys in Antarctica with other bacteria on the valley floor feeding off the organic material contained within those rocks that fall to the valley floor; living in the glaciers of Antartica and Greenland; living in the hydrothermal vents deep in the ocean; and living in the hot springs of places like Yellowstone. Even though these studies have openned our eyes to a new range of possibilities, all of these organisms are related, genetically and biochemically, to organisms that are more familiar to us: cute, two-eyed mesofauna.
One common approach to uncovering life’s origin has been to examine the workings of the cell and extrapolate backwards in time to present plausible scenarios as to how they might have arisen. This is molecular archaeology. With the development of DNA sequence technology and other biochemical and biophysical techniques, we can trace our genetic history back a long way. Such an approach has led to the popular notion of a Last Universal Common Ancestor (LUCA). However, defining the genetic makeup of LUCA has been difficult. While sequences of many individual genes can be assembled into consistent phylogenetic trees, any collection of genes cannot be assembled into a self consistent tree at the deepest branches. In other words, the history of some gene pairs is consistent with having a common ancestor but the history other gene pairs seem to be consistent with a different common ancestor. This begs the question of whether there was a unique LUCA or whether our current extant organisms condensed out of a community whose genetic makeup was fluid. Rather than a community of organisms, early life could have been communities of genes living within cells with the genes capable of moving from one community to another. One important thing to understand is that these are not cells in the way that you have learned in biology class. Rather they are membraneous enclosures containing genes and enzymes that catalyze each other’s synthesis. Physical isolation would lead to ever increasing incompatibility between communities due to genetic drift and stochastic fixation of alleles. Eventually, genes in the different communities could only exist within their community of origin or close relatives, eventually leading to the three known domains of life: Bacteria, Archaea and Eukaryotes. The Tree of Life may be more like a mangrove forest than an isolated live oak.
Such a process is still at work today. Genes in bacteria are on the move, a process called horizontal transfer. Indeed, applying the terms genus and species to bacteria today is problematic. The E. coli that colonize your gut are related to the E. coli that will make you sick, but the E. coli that will make you sick has ~25 % more genes than the ones in your gut.
So far, genetics can take us back to the time of genes, but how did these arise? We now get into a murky world of theory for which experimental constraints and results leave few clues to build upon. This is somewhat analogous to the surface/time of last scattering that leads to the cosmic microwave background and sets a limit on the what we can see with light. To delve into this murky world, we have to look at the basic biochemistry of nucleic acids, proteins, and membranes. These are all macromolecular structures made up of individual building blocks: nucleotides, amino acids and fatty acids, respectively. Each macromolecule participates in the synthesis of the others: proteins synthesize the nucleotides and the nucleic acids, which in turn synthesize proteins, which synthesize membranes that function with proteins to capture energy to drive the synthesis of the building blocks and macromolecules, etc., etc.
The first important advance was in the recognition that proteins can act as catalysts, i.e. enzymes. Moreover, enzymes act with amazing specificity, making organic chemists jealous. Their specificity is due to their amino acid sequence and structure, folding in such a way to bring together particular amino acids (and cofactors) in such a 3D arrangement to specifically bind its preferred substrates and facilitate a chemical reaction. Early on with respect to origin of life theory, it became evident that enzymes could not directly synthesize other enzymes since each peptide bond would require an enzyme for its catalysis, which would in turn require different enzymes to catalyze their synthesis: an infinite regression…major problem.
RNA to the rescue? The discovery of the structure of DNA and the subsequent elucidation of mechanisms of replication, transcription and translation removed the infinite regress problem for protein synthesis. Moreover, RNA was found to have catalytic potential of its own: it could catalyze the cleavage and rejoining of RNA molecules, and more importantly, rRNA catalyzes the formation of peptide bonds in the ribosome, carries the amino acids on tRNA to the ribosome, and through the interaction of the tRNA with the mRNA decodes the sequence of the message. Thus, a sequence of nucleic acid could specify the sequence of a protein. Given that RNA replication is template directed along with the expanded catalytic potential, it took only a small logical leap to propose what has become the RNA World hypothesis: RNAs could drive their own synthesis as well as several other reactions.
There is much going for this hypothesis. For me, some version of the RNA world existed prior to the RNA directed protein synthesis, the RNP world. However for me, there are a few nagging questions and a few thermodynamic bridges to cross. The basic one is how were the first nucleosides and nucleotides synthesized? Was it merely random chemistry, or were there pre-existing self-sustaining and perhaps replicating metabolisms that predated the rise of the RNA world?
A metabolism first perspective, my personal bias, is motivated by what is perhaps the weakest link in the RNA world scenario: the concentration problem. How could you accumulate a high enough concentration of building blocks to kick start the RNA world? Sure, chemistries on Earth, in comets, in meteors, in molecular clouds, and on other worlds produce amino acids, nucleic acids, sugars, etc., but the problem is one of dilution. If the primordial soup is too dilute, nothing will happen.
To begin to address this obstacle, we again must examine current organisms for hints. Some of the most deeply branching known organisms are the methanogens and acetogens (makers of methane and acetic acid) that fix CO2, supplying all of their carbon needs by using H2 and other reduced compounds as electron donors to reduce CO2 and generate ATP. More importantly, the core of the process in these organisms involves the citric acid cycle (TCA cycle, Kreb’s cycle). If you have taken any biology, you were likely forced to memorize the cycle and usually in one direction, from citric acid to oxaloacetate. But in these chemoautotrophs (organisms that fix CO2 using non-organic chemical energy) the TCA cycle runs in reverse, incorporating CO2 at the steps that release CO2 when run in the familiar forward direction. Since forward and reverse are somewhat arbitrary, it is better to talk of the oxidative (forward) and reductive (reverse). There are a few extra steps that connect to the rTCA cycle that I won’t get into, but I just point out that each of the compounds is required for the cycle and is generated by the cycle. In other words, the compounds are autocatalytic. To put things in terms more familiar to the oxidative TCA cycle, one can call oxaloacetate a catalyst since it emerges unchanged in one turn of the cycle.
Interestingly, many of the enzymatic reactions of this cycle are catalyzed by enzymes that have iron-sulfur compounds at their catalytic core. These sorts of transition metal-sulfur compound natually occur at hydrothermal vents and form structures with micro compartments, potentially an ideal environment providing the energy and raw material for the catalysis and concentration of compounds required to get a more robust metabolism started leading to the origin of life.
Certainly, there are huge gaps in knowledge both in our understanding of our current world and of the deep past. At its core, science is an inquiry into the unknown, imagination in a straitjacket.