We all know the story of the Miller-Urey experiment. In 1953, a young graduate student named Stanley Miller ran an off-the-wall experiment: he ran water, methane, ammonia, and hydrogen in a sealed flask with a pair of electrodes to produce a spark, and from those simple building blocks discovered that more complex compounds, such as amino acids, were spontaneously produced. Stanley Miller died in 2007, and in going through his effects, the original apparatus was discovered, and in addition, several small sealed vials containing the sludge produced in the original experiment were also found.
This isn't too surprising. I've gone through a few old scientists' labs, and you'd be surprised at all the antiquities they preserved, all with notes documenting exactly what they are. It's habit to keep this stuff.
Now the cool part, though: the scientists who unearthed the old samples ran them through modern analysis techniques, which are a bit more sensitive than the tools they had in the 1950s. In 1953, Miller reported the recovery of five amino acids from his experiment. The reanalysis found twenty two amino acids and five amines in the vials. He was more successful than he knew!
Yes, I know that Miller's reducing atmosphere is no longer considered to be an accurate representation of the ancient earth's atmosphere. However, the experiment still supported a key idea: that the synthesis of these organic compounds did not require any kind of guiding hand, but would naturally emerge from unassisted chemical reactions. Furthermore, the authors of this paper argue that while it was not a good model of the global atmosphere, it might still model local conditions in isolated areas.
Geoscientists today doubt that the primitive atmosphere had the highly reducing composition Miller used. However, the volcanic apparatus experiment suggests that, even if the overall atmosphere was not reducing, localized prebiotic synthesis could have been effective. Reduced gases and lightning associated with volcanic eruptions in hot spots or island arc-type systems could have been prevalent on the early Earth before extensive continents formed. In these volcanic plumes, HCN, aldehydes, and ketones may have been produced, which, after washing out of the atmosphere, could have become involved in the synthesis of organic molecules. Amino acids formed in volcanic island systems could have accumulated in tidal areas, where they could be polymerized by carbonyl sulfide, a simple volcanic gas that has been shown to form peptides under mild conditions.
So good work, Dr Miller!
Johnson AP, Cleaves HJ, Dworkin JP, Glavin DP, Lazcano A, Bada JL (2008) The Miller Volcanic Spark Discharge Experiment. Science 322(5900):404.
16 Comments
GvlGeologist, FCD · 17 October 2008
Fantastic!
Is there any possibility that continuing reactions in the sealed vials, long after the end of the 1950s spark experiments, may have contributed to the formation of some of the additional amino acids, or did their synthesis require the extra energy in the sparks?
Abiogenesis, after all, would most likely be a series of processes that would have taken long time periods (despite the suggestions by creationists).
IANAchemist.
Kurt Hollocher · 17 October 2008
Although the general concensus is that Earth's early atmosphere was relatively oxidizing and dominated by N2 and CO2, that interpretation is not easily reconciles with several pieces of evidence from Archean rocks. Science marches on and there are alternative models that might fit the complete set of evidence better. To those who are interested I suggest looking up: Shaw, 2008, Earth's atmosphere-Hadean to early Proterozoic, Chemie der Erde, v. 68, p. 235-264.
fnxtr · 17 October 2008
I was just reading about early organic chemistry last night, and wondering why the reality-deniers don't use terms like 'Woehlerist' in a derogatory fashion, to paint modern chemistry as a cult of personality for those who deny the existence of elan vital.
Tracy P. Hamilton · 17 October 2008
Kurt,
There was also the paper that said the earth atmosphere was more reducing than generally thought because outgassing of reducing gases kept atmospheric levels high.
http://solarsystem.wustl.edu/our%20reprints/2005/dps%20abstracts/Early%20Earth%20abstract.pdf#search=%22Fegley%20schaefer%20reducing%22
A reducing atmosphere from out-gassing of the early Earth
Laura Schaefer and Bruce Fegley, Jr.
Earth’s present atmosphere originated from out-gassing of volatile-bearing grains. We
calculated the composition of volatiles out-gassed from chondritic planetary bodies. We
present results for average CI, CM, CV, H, L, and EH chondrites, which are the building
blocks of the Earth. From the oxygen-isotope mixing (OIM) model, we calculated a
composition of 70% EH, 21% H, 5% CV, and 4% CI chondritic matter for the early
Earth. The major out-gassed volatiles for these starting compositions are CH4, N2, NH3,
H2, and H2O. The Miller-Urey experiment demonstrated that a reducing atmosphere like
this generates amino acids and other organic compounds that are essential for the
formation of life. This work is supported by the NASA Astrobiology Program.
SteveF · 17 October 2008
Mike Elzinga · 17 October 2008
GvlGeologist, FCD · 17 October 2008
Ravilyn Sanders · 17 October 2008
Any one continuing the experiment? Using more modern apparatus, updated consensus about the early atmosphere etc?
SteveF · 17 October 2008
SteveF · 17 October 2008
I should add that Cleaves et al is Stanley Miller's final paper.
a lurker · 17 October 2008
Well a bunch of graduate students have a project: Redo decades of abiogenesis experiments with modern analytical equipment to see what was missed the first time.
I would be interested to know if the result was just stuff that the technology that Miller had could not detect, the sample slowly reacting over the decades in the fridge, or both?
rimpal · 17 October 2008
I am waiting for a reaction from the world-famous biologist and neo-creationist, author of "Tales from One Big Bluffer" aka "The Pathetically Ignorant Guide to biology" - Jonathan Wells
snaxalotl · 18 October 2008
"the experiment still supported a key idea: that the synthesis of these organic compounds did not require any kind of guiding hand"
this is the entire point as far as addressing creationists. it's easy to take your gloating 20-20 hindsight and imagine that this experiment was a "failed proof that life arose from ancient conditions" ... but what makes it so amazing is the context at the time, that amino acids were invariably markers of biochemistry (or systematic attempts to construct amino acids). To suddenly find that amino acids could pop out of something relatively unsophisticated was the point at which amino acids turned out to be not so special. This seems to be a point that creationists aren't being hit over the head with nearly enough.
Torbjörn Larsson, OMa · 18 October 2008
Sprocket · 20 October 2008
But perhaps God's guiding hand appears whenever a life- creating event takes place.
We could test this by having a control in which God is excluded by surrounding the reaction vessel with satanic regalia, pentagrams etc. We could also see if reaction rates are increased in the presence of a crucifix or a bible.
It would be a dangerous experiment, as it's possible that maximum abiogenetic rates could be achieved in the presence of, say, the Amduat, thus proving that the abandonment of pyramid building was a mistake.
Veridoktoru · 21 October 2008
"AAAC ExoPlanet Task Force outlines a 15-year strategy “to identify earth-like planets in the habitable zones of bright, nearby stars”.
That's really exciting news.