Old scientists never clean out their refrigerators

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Blogging on Peer-Reviewed Research

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!

miller.jpg

Moles (relative to glycine = 1) of the various amino acids detected in the volcanic apparatus vials. Amino acids underlined have not been previously reported in spark discharge experiments. Values for amines are minimum values because of loss due to their volatility during workup.

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

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.

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.

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.

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%20[…]t.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.

Kurt,

Kurt Hollocher said:

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.

It’s not my area of expertise by any stretch of the imagination, but I thought the evidence was for a weakly reducing or possibly neutral atmosphere during the relevant period. For example, Kasting and Catlin (Ann Rev Astron Astrophys, 41, 429-463, 2003) talk about “the entire period (4.5–2.3 Ga) when the atmosphere remained reduced.” Or from Kasting and Howard (Phil Trans B, 361, 1733–1742, 2006) we have “the present wisdom is that highly reduced CH4–NH3 atmospheres are unlikely, while weakly reduced CO2–N2 atmospheres with small amounts of H2 (approx. 0.1%) are likely”.

It’s worth pointing out that amino acid synthesis doesn’t just occur in highly reducing atmosphere. It could take place in a neutral atmosphere as demonstrated in:

Cleaves, H.J. et al. (2008) A reassessment of prebiotic organic synthesis in neutral planetary atmospheres. Origin of Life and Evolutution of the Biosphere, 38, 105-115.

and in weakly reducing atmospheres, particularly if there is an appropriate ratio of hydrogen to carbon. It’s recently been shown that hydrogen concentrations probably were quite high (although this work remains controversial):

Tian, F. et al. (2005) A Hydrogen Rich Early Earth Atmosphere. Science, 308, 1014-1017.

GvlGeologist, FCD said:

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.

It is indeed possible. Just from the physics alone we know that some reactions can’t take place until the average energy levels are reduced so that certain bonds can pop into place.

In many kinds of reactions, one has to “pump” them to higher levels and then let them relax into lower levels that are less likely to be reached from the ground state or are constantly broken up again by the exchanges of energy in the system. In the case of chemical reactions, yes, many of these are much faster than the many years that these vials were stored, but once some compounds are formed, they become the catalysts for slower reactions that occur over much longer periods of time.

Mike Elzinga said: It is indeed possible.…

Thanks!

Any one continuing the experiment? Using more modern apparatus, updated consensus about the early atmosphere etc?

Ravilyn Sanders said:

Any one continuing the experiment? Using more modern apparatus, updated consensus about the early atmosphere etc?

Yep, see:

Cleaves, H.J. et al. (2008) A reassessment of prebiotic organic synthesis in neutral planetary atmospheres. Origin of Life and Evolutution of the Biosphere, 38, 105-115.

I should add that Cleaves et al is Stanley Miller’s final paper.

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?

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

“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.

snaxalotl said:

This seems to be a point that creationists aren’t being hit over the head with nearly enough.

Yes, well, as long as creationists attack tested science like evolution the answers will be skewed. But one of their purposes in doing that is preemptive, so it is indeed pertinent to not let them follow their strategy unchallenged.

And in the near future this will likely be tested. I hear from the Division of Planetary Sciences (DPS) of the American Astronomical Society annual meeting that the AAAC ExoPlanet Task Force outlines a 15-year strategy “to identify earth-like planets in the habitable zones of bright, nearby stars”. If recent statistics bears out AFAIU from their report the planets that can be spectroscopically investigated for life (say, by displaying oxidative-reductive imbalances such as concurrent oxygen/ozone and methane) can be numbered in the hundreds, already by todays technical knowhow!

The odds that we could have statistics on time dependent characteristics of biospheres in our lifetimes may be high. We may not know if that life builds on amino acids, but we may know characteristics of other markers of biochemistry such as photosynthetic systems well. We may also find that abiogenesis is not so special.

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.

“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.

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This page contains a single entry by PZ Myers published on October 17, 2008 6:45 AM.

Dr. Randy Moore receives 2008 Evolution Education Award was the previous entry in this blog.

Will the availability of C-sections give humans bigger brains? is the next entry in this blog.

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