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Primordial Soup: Interview with Stanley Miller
An anonymous reader writes "Stanley Miller's classic 'primordial soup' experiments showed that 13 of the 21 amino acids necessary for life could be made in a glass flask. For its fifty-year commemoration, Miller is interviewed today and reflects on what Carl Sagan
called 'the single most significant step in convincing many scientists that life is likely to be abundant in the cosmos.'"
showed that 13 of the 21 amino acids necessary for life could be made in a glass flask
:-)
Of course, certain products of his experiments often indicate that not all of them are necessary. These products are, of course, "intellectual property lawyers."
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Primordial Recipe: Spark and Stir
Date Wednesday, May 14 @ 00:48:06
Topic Extrasolar Life
No single experiment, according to Carl Sagan, has done more to convince scientists that life is 'likely abundant in the cosmos' than the work fifty years ago by then graduate student, Stanley Miller. This week celebrates his milestone publication, and Astrobiology Magazine interviewed him about his work and reflections today.
Primordial Recipe: Spark and Stir
by Astrobiology Magazine staffwriter
Fifty years ago on May 15, 1953, a University of Chicago graduate student, Stanley Miller, published a landmark two-page paper in Science magazine. He considered if amino acids could be made from what was known about the early Earth's atmosphere. Could the building blocks of life be cooked up?
"... some warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity etc...", Charles Darwin, on the origins of life in tidal pools
Credit:Smithsonian
Miller began his paper:
"The idea that the organic compounds that serve as the basis of life were formed when the earth had an atmosphere of methane, ammonia, water and hydrogen instead of carbon dioxide, nitrogen, oxygen and water was suggested by Oparin and has been given emphasis by Urey and Bernal. In order to test this hypothesis..."
When Miller first presented his experimental findings to a large seminar, it is reported that at one point, Enrico Fermi politely asked if it was known whether this kind of process could have actually taken place on the primitive Earth. Harold Urey, Stanley's research advisor, immediately replied, saying 'If God did not do it this way, then he missed a good bet'. The seminar ended amid the laughter and, as the attendees filed out, some congratulated Stanley on his results.
Although Miller had submitted his paper in mid-December 1952, one reviewer did not believe the results and delayed its publication until May 15th. Later Carl Sagan would do many experiments varying the chemical percentages, but described the Miller-Urey experiments as "the single most significant step in convincing many scientists that life is likely to be abundant in the cosmos."
Early Earth: Flash in a Flask
Even today, only a few definitive things are known about what the Earth might have been like four billion years ago. It is thought that the early sun radiated only 70 percent of its modern power. No free oxygen could be found in Earth's atmosphere. The rocky wasteland lacked life. Absent were viruses, bacteria, plants and animals. Even the temperature itself is uncertain, since three schools of thought today maintain that the Earth could have been alternatively frozen, temperate or steamy.
Charles Darwin imagined life springing from a temperate world, with small ponds or runoff channels. Compared to diluted chemistry in a vast ocean, repeated evaporation and refilling have possible advantages, to find just the right concentrations somewhere so that biochemistry could begin. Glaciers, volcanoes, geysers and cometary debris potentially resupplied this primordial pond with both energy and more complex organic compounds. That is a scenario requiring relatively temperate starting conditions, and more extreme possibilities are also in the mix.
If the early Earth was a cauldron of volcanic activity, then seepage of acidic gases and heating might have circulated vital compounds to the surface. These vents may have been underwater, and precursors to biochemistry like acetic acid may have become reactive in combination with carbon monoxide. Alternatively, if the early Earth lacked any greenhouse of blanketing carbon dioxide, life could still have begun in a ball of ice. When combined with water, even a thin atmosphere of organics (formaldehyde, cyanide and ammonia) can create some building blocks of life (such as the amino acid, glycine). Thawing this 'snowball Earth' could then be triggered by a chance collision with large comets or meteors.
Terrestrial options for ea
I stopped eating primordial soup because the amino acids keep giving me heartburn.
All your base are belong to us!
from October 1996: Exobiology interview
On a related note: exobiology vs astrobiology? which do people prefer? (The definitions are in the links)
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For two years, I bugged my Biology teachers to let my try the Miller experiment with the school's equipment. (Of course, I was the same one who wanted them to let me make a gauss rifle, a betatron, and potato gun...)
I remember being fascinated when I first heard of the experiment. It seemed so 'important,' despite the fact that they brushed right over it and no one else in my classes understood or cared.
Of course, now I'm in college, and I can try all of these things with my own equipment.
GeekNights!
Late Night Radio for Geeks!
You're whining that the odds are too big, but it's guys like Stanley Miller that are trying to figure out exactly how big those odds are.
You might want to actually provide some facts as to why Carl Sagan was wrong, rather than make an ad hominem attack. Most truly academic scientists generally take a bit more convincing than just being told that, "The guy was an asshole, so he must be wrong."
Education should provoke thought. Just training kids to pass tests is of no value. What you did, analysing your results and thinking about _why_ you got them shows far more 'talent' than someone who just repeated an experiment that is guaranteed to give good results.
Sigh! Rant over. It is just crushing to see very little evidence of people designing their science lessons to impart the ability to think, like the guy who wrote Clouds in a Glass of Beer did.
Help children born unable to swallow - www.tofs.org.uk
The significant thing is that Miller was able to produce amino acids in the first place. leonbrooks is using the classic fundamentalist creationist tactic of taking a scientific success and portraying it as a failure because the experiment did not meet 100% of the artificial requirements that he has generated for it.
:-)
This is the same thought process that causes them to say "Evolution can't possibly be true because there is a missing link between species A and species C," and then when species B is discovered, they say "Aha! Now you have even bigger problems, because there is no link between A and B, and B and C!"
"Contact" [geocities.com] gave him a little recognition only because the movie was made believable (and bias I might add)
What? Are you suggesting that the movie Contact, which was a fun movie, but also new age UFO-cult pop drivel, led to Carl Sagan being more respected among SCIENTISTS?
Contact was BIASED? It's a work of fiction! What shortcomings of impartiality did you detect?
Most TRUELY academic scientists will tell you there seems to be "some" evidence of a creator
Well, Carl Sagan, it is true, is not as highly regarded for his own, unique, scientific contributions as one might believe watching PBS.
However, he had mountains of respect compared to anyone who pointed to anything specific and said it was evidence for the existence of a creator. It is perfectly well regarded in respected circles to quote Einstein "I believe in Spinoza's God who reveals himself in the orderly harmony of what exists", particularly if you are being harassed by religious nuts about your own beliefs - volunteering such sentiments in a TRUELY ACADEMIC setting is the mark of a crackpot, however.
To say that any particular observed phenomenon is evidence, however indirect or minor, of some sort of supernatural providence which exceeds our capacity to understand is the mark of a TRUELY desperate religious nut - not a TRUELY academic scientist.
Lottery = your chances in getting picked out the pool may be one in a million, but your chances of picking the right number on the right day and being that one in a million are impossible odds.
I'm a bioinformatician - you may be attempting to communicate something valid, but what you say is nonsense. If your odds of getting picked in a lotterry are one in a million, and you enter the loterry once, you have a one in a million chance of winning the loterry. If you have to enter the single, right loterry, and there are a million of them, the odds are one in a trillion (a million squared.) In any case, not "incalculable."
If you enter the loterry every day for a billion years and have a chance of winning each time, even vanishingly small odds
Furthermore, while it is true that the odds of life arising around any given star may be extremely small, even over a billion year timespan - Sagan's point remains valid, there are about a SEXTILLION (that's ten ^ 21) stars in known universe.
The reason that we don't have enough information to calculate the odds of life arising on an earth-like planet is because we don't have enough information. The one earth-like planet we observe, the Earth, has life on it, but we're here, so our single observation is hopelessly biased.
On the other hand - unless they are "TRUELY academic" - most scientists feel that life arose as a purely chemical process, from chemical laws which were the same at that time as they are today.
Now, we don't yet know all of the steps that need to occur in order for life to arise. However, even given our broad ignorance, we can conclude that you need organic monomers of some kind (assuming organic life such as ours - an entirely seperate question) is Step 1.
Whatever the probability of success of steps 2...n, the more likely you are to succeed at Step 1, the more likely the entire process is to succeed.
Stanley Miller showed that there conditions, conditions not inconceivable on a young, earthlike planet, under which the formation of these molecular monomers is highly likely.
Therefore, the entire series of steps becomes more likely. Groundbreaking work.
Not a single scientists has been able to prove 100% that life exists elsewhere, only propoganda and conjecture.
Entirely true. We may very well be alone in the universe. However, our best estimate is that we are not. Conjecture, yes, propoganda - only in so far as all scientific endeavor is propoganda against superstitious beliefs.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
The production of amino acids on the early earth is neccessary for spontaneous generation, but amino acids are extremely simple compared to proteins and cellular structures. One would expect amino acids whether the spontaneous generation of life happened or not.
Saying that the existance of amino acids on an early earth proves spontaneous generation is almost like saying the existance of carbon and water on a planet proves the existance of life on that planet. Inconclusive!
David Pesta
B.S. Biochemistry
So, the chances are actually incalculable. Lottery = your chances in getting picked out the pool may be one in a million, but your chances of picking the right number on the right day and being that one in a million are impossible odds. Then you have the odds of actually claiming your prize and meeting the eligibility/legitimacy of the prize.
;)
Odd. I could swear that there are people who've actually won the lottery... a couple hundred in America, I wager, which puts them at just about 1 in a million.
Statistic impossibilities mean "don't plan on it happening to you," not "it'll never happen to anyone."
Racemic mixtures are not decompsed anything. They are mixtures of "mirror-image" molecules. A completely racemized mixture is one with equal numbers of "left" and "right" members. Presence of both will not prevent you from using one or the other.
Look at you set of hands, one is racemic "left" and the other is racemic "right". You have a completely racemized mixture of hands. This does not deny you use of your left hand.
If amino acid procduction is industrial, usually you get (depending on the process) a mixture of the two racimic (D and L) formations that an amino acid can take. They are mirror images of each other.
Why is this important, well on planet Earth, almost all amino acids involed in life are of type L. (Metorites and non-living processes contribute the majority, if not all, of the D racemes discovered today)
Why only L-amino acids? Today we do not "know" with 100% certainty, but the theory is a living system, for whatever reason, started producing L-amino acids, which unbalanced the ratio. Other living systems (or perhaps the same one) which harvestd these L-amino acids survived and thrived in this L-amino acid rich environment while those that required D-amino acids may have never existed or may have died out due to competition.
Okay then, please set out the creationist position in terms we simple atheists can understand. please try and avoid circular arguments.
I used to have a better sig than this, but I got tired of it
Replies to several different posts (sorry for the lack of attribution): /Ah, but does he mention that his amino acids... /broke down as fast as they were made (in a /carefully customised device, not in the wild), /and were completely racemised at formation? Or /that no evidence of a reducing atmosphere exists?
/Also Miller had to create a "trap" to collect the /amino acids being formed to protect them from /breaking down again. What would the comparable /"natural" trap be?
/As a student of Biological Anthropology, I have /had the oppertunity to take a history of /biological anthropology in which Miller was /mentioned. Interesting guy, but the theory is not /supported any more except by the few staunchest /researchers. In other words, this is pop science. /It survives in text books (like many other /evolutionary inaccuracies that nobody seems to be /willing to update). In truth, the experiment did /not conclude much. In short, the amino acid /theory in reality did not produce very much at /all
Amino acids tend not to break down much. They are exceedingly stable once made. Those that happened to wander back into the electric current might have suffered, but the majority would have stayed safely in solution. The chemical reaction was proceeding in the gas phase; the products were sequestered in the water.
The products are racemic amino acids. Several plausible hypotheses have been put as to how it happened that the L amino acids became predominate: circular dichroism in natural radiation, preferential decompostion of D 14C labeled amino acids, etc.
We don't know all that much about the exact composition of the atmosphere at every time in the earth's history, but the fact that high-energy processes can give amino acids from simple precursors trumps all nit-picking.
The natural trap would be water. High energy events are always happening in the atmosphere (lightning, UV rays, cosmic rays). Lighting blasts convert nitrogen to nitrates. Roughly 10% of the nitrate in soil comes from nitrogen transformed by lightning, and the nitrates are trapped by water. The point to take home from the Miller experiment is that the small, high-energy intermediates formed by these processes can combine to form biologially complex building blocks.
This is just wrong. The conclusion drawn from the results of the experiment was revolutionary. It is of at least on the scale of Wohler's synthesis of urea, a biochemical, from "dead" cyanogen and ammonia.
If Slashdot were chemistry it would look like this:Cadaverine
> From what I recall (and a quick Google search), there is a big problem with Miller's experiment: the "environment" that Miller created was nothing like the environment of pre-biotic earth, becaus Miller's "atmosphere" was oxygen free, but geological evidence indicates that free oxygen has always been present on earth.
No, the existence of iron ore shows otherwise. It precipitated out of the seas when oxygen started building up in the atmosphere; in an oxydizing atmosphere there could never have been enough iron in the oceans to for the massive deposits we actually find.
BTW, I learned this a while back by spending a very little time with google. Make sure you're not getting all your "facts" from creationist Web sites.
> Also Miller had to create a "trap" to collect the amino acids being formed to protect them from breaking down again. What would the comparable "natural" trap be?
Out of my league, so I'll let someone else answer.
Though of course an obvious 'trap' is "life", e.g. if some of the AAs were incorporated into some kind of primitive self-replicator.
> Finally, the mix of both D and L aminos in Miller's soup presents a major problem. Living cells only use L amino acids. D aminos and proteins are toxic.
One hypothesis is that the earliest life formed by polymerization on a quasi-crystaline base such as clay, which could show a preference to one orientation over the other.
Another hypothesis is that both orientations were once used by life forms, but that the luck of the draw meant one crowded the other out. (You get that kind of thing in hereditary systems; a long time ago Scientific American had an interesting article about how surnames dissappear from populations over time due to differential breeding rates and essentially random factors.)
> So it seems to me that what Miller demonstrated is that creating amino acids requires an intelligent mind controlling the process.
Ignoring the problems with the claims you base that conclusion on, that is a major non sequitur. It is tantamount to saying "I rolled my car over yesterday, proving that cars can't be rolled over due to natural causes."
Sheesh, evil *and* a jerk. -- Jade
For more information on Miller and prebiotic Earth, here is a quotation from an Angew. Chem. review article by Kay Severin called Hot Stones or Cold Soup? New Investigations on the Endogenous Origin of Organic Compounds on Earth (Angew. Chem. Int. Ed 2000, 39, No. 20). It pretty much sums up the Miller reactions, why they're wrong, and what people think now:
... was carried out almost fifty years ago by Stanley L. Miller, at that time a PhD student in the group of Harold Urey in Chicago. Miller was able to show that electric discharges in an atmosphere of methane, ammonia, hydrogen, and water led to the formation of significant amounts of various amino acids. Experiments of this kind were repeated in numerous variants. If reducing gases were employed mixtures of organic compounds of low molecular weight could be detected in many cases. This has led to the popular idea that the primordial ocean resembled a nutritious soup.
"The most famous experiment
"But the possibility that earth once had a reducing atmosphere is questioned. A well known argument against it is the high photolability of methane and ammonia. Because a shielding layer of ozone was missing a high concentration of these gases is believed to be unlikely. Furthermore, several other results point to a neutral atmosphere of CO2 and N2. Given the fact that the atmosphere was based on an unproductive mixture of CO2 and N2 the nutritional value of the primordial ocean drops significantly.
"An alternative scenario has been propagated for several years by [Gunter] Wachterhauser. Instead of a primordial soup he favors hot minerals as the place where organic molecules were initially built as life subsequently emerged. Especially sulfur-containing minerals like pyrite are proposed to have acted as an energy source and catalyst both under the extreme conditions found in hydrothermal or volcanic vents."
Basically, primordial soup syntheses (like Miller's reactions) are out and hot rock syntheses are in. These hot rock procedures have much much much lower yields, but people are slowly figuring out how to build amino acids through them. For instance, people, headed by Wachterhauser, have figured out how to carbon fixate (condense) carbon monoxide and carbon dioxide into organic building blocks for amino acids. For instance, in early 2000, Chen and Bahnemann were able to convert CO2 and water to small organics (acetaldehyde, ethanol, acetic acid) at high pressures and temperatures. Similarly, people have figured out how to take amino acids and convert them into peptides under high temperature and pressure situations.
However, to date no one has been able to actually make an amino acid through these techniques. As a result, the proof that amino acids were delivered by comets or meteorites (true fact, this is not an x-file) and now space dust, becomes much more appealing. Once the building blocks arrived on Earth, these hot rock syntheses could have taken over.
This is true. and no one is saying that amino acids jumped up and formed life the second there were enough to matter. Life took time to form, a LOT of time.
I am still baffled by those who think that life just happens.
Life doesn't "just happen". It takes the right ingredients, energy and time. Possibly millions of years of time.
The Earth's atmosphere today is much more hospitable to life
No, it's not. Oxygen is a poison. Life has adapted to the presense of oxygen in the atmosphere. Oxygen activley destroys the basic building blocks of life when not protected.
but we still do not see amino acids coming together and organizing into complex proteins or anything resembling life.
And we never will on Earth. The atmosphere is all wrong for it. And we will have to wait a long time to see it. It's not like waiting for your cheese to get moldy.
This can't even be done in the laboratory.
For the reasons listed above. And creating life is a hell of a lot more complex than just creating amino acids. In the steps to creating life, this is on the same level as buying one adjustable wrench in the construction of the Empire State Building.
It is contrary to the 2nd law of thrmodynamics.
Really? How? Life is not a closed system. It requires energy from an outside source. The Sun provides the power that lets life go on.
I don't believe in spontaneous generation. The odds of it happening are beyond astronomical.
All you need is a positive non-zero probablity for something to eventually happen. We have no idea how amny times life almost formed and then died before it finally succeeded. Even with one chance in one-hundred million, if you have millions, and maybe billions of years for something to happen, it just might. And it only has to succede once.
Boobies never hurt anyone. - Sherry Glaser.