The Miller–Urey experiment revisited
Published: 15 March 2015 (GMT+10)
This feedback answers Aleksey K. of Ukraine, who asked about revisitation of the iconic Miller Urey experiment. The media claimed that it could have produced many more amino acids than previously thought. This is followed by a box about the nature of Earth’s early oxidizing atmosphere, which falsifies one of the important premises behind the experiment.
This article1 says that the new analysis of the old products received by Miller and Urey in their experiment, made by Miller’s student, Jeffrey Bada in 2008, found 23 different amino acids. So can we still argue that the Miller–Urey experiment found only few of the amino acids and didn’t find some specific ones, critically important for life? The Evolution’s Achilles Heels film also makes this statement.
I understand that there are many other, more important insurmountables for the origin of life, but maybe we shouldn’t use arguments that are disproved, like this one?
Thank you for your answer in advance.
Aleksey K., Ukraine
Dr Jonathan Sarfati responds.
Dear Mr K.
Thank you for writing to CMI.
We were long aware of this re-analysis, and remain singularly unimpressed. Long before this, in my own organic chemistry classes, the professor (top ranking lecturer in the New Zealand and UK system) of organic chemistry, and himself a believer in chemical evolution, pointed out that the original Miller experiment was so influential because of the new analytical techniques of the day. This enabled trace molecules to be detected from the tarry mess. So the yields of even the simple glycine were very low, to say nothing of most other amino acids that are in far lower quantities. Bada’s new experiment used even more refined techniques such as HPLC and liquid chromatography–time of flight mass spectrometry, to separate compounds that are very similar chemically.
The original paper by Bada and his team has closed access,2 but his more recent paper in PNAS (2011) is open.3 Studying Table 2 in this paper showed that the 23 amino acids are not all relevant, since most life uses only 20. The detected amino acids include β-alanine, α-aminoisobutyric acid, the α-, β-, and γ-aminobutyric acid isomers, isoserine, ethionine, which are not found in proteins. And they failed to detect the proteinaceous amino acids phenylalanine, proline, histidine, tyrosine, lysine, asparagine, arginine, or glutamine.
It’s notable that some of the proteinaceous amino acids are destroyed by the very conditions that produce them (and this ignores the unjustifiable investigator interference of a trap to isolate the products before the energy source can destroy them), or are readily oxidized (see below for recent evidence for an early oxidizing atmosphere).
It is important to note that cysteine was not detected in the samples analyzed here. However, many samples did contain cysteamine and homocysteic acid, which are degradation products of cysteine and homocysteine, respectively. The presence of these sulfur compounds suggests that cysteine was initially present in the samples, but over time the cysteine was degraded by oxidation, among other mechanisms, because these samples were not stored under anoxic conditions.
Also, since any further steps, such as making proteins from them, require highly concentrated amino acids, finding tiny trace amounts is worthless. What they did find is four amines, which would act as chain terminators as explained in Origin of life: the polymerization problem. It’s also notable that they could conclude that the products were not contaminants precisely because they were racemic, an equal mixture of ‘left-handed’ and ‘right-handed’ forms. This presents another intractable problem for chemical evolution, because life requires exclusively one-handed amino acids and sugars.
So in conclusion, I think that the argument in the EAH film is still sound. We indeed keep a page, Arguments we think creationists should NOT use, a widely accessed page with which even Richard Dawkins, the Apostle of Atheopathy, praised. However, we don’t think that we need to add this to the list.
Was earth’s atmosphere really reducing as Miller and Urey thought?
For the last six decades, it has been a widely believed myth that life on Earth evolved in a primordial soup. The basic chemicals in the soup were allegedly generated by ultraviolet radiation and lightning in a primordial atmosphere unlike the present one. It was allegedly ‘reducing’, meaning it contained hydrogen-rich compounds like methane (CH4) and ammonia (NH3) and lacked oxygen. Our current ‘oxidizing’ atmosphere would be hopeless, because oxygen would destroy the so-called building blocks, and indeed prevent their formation in the first place.
It surprises many to realize that this theory is not driven by evidence but by the dogma that life evolved by spontaneous generation—no intelligence allowed, by decree. For example, a primordial soup would have left traces of nitrogen-rich compounds, but they have never been found anywhere on Earth. Also, the methane-ammonia atmosphere has largely been discarded, and there is much evidence that oxygen existed from a very early time, even according to evolutionary ‘dating’.
A final blow was dealt late last year. Scientists in the New York Center for Astrobiology at Rensselaer Polytechnic Institute analyzed what they called the oldest minerals on Earth: zircons, ‘dated’ at 4.35 billion years old.4,5 These contain a rare-earth metal called cerium. The more oxidizing, the more cerium will be found in the highly oxidized form (Ce4+), and less at the more reduced form (Ce3+).
The conclusion? A report said, “The calibrations reveal an atmosphere with an oxidation state closer to present-day conditions.” Thus Earth was never good for chemical evolution. But since the researchers were unwilling to abandon their dogma, they resorted to the desperate measure of panspermia: the building blocks came from outer space. This of course just shifts the many other intractable problems with chemical evolution elsewhere, beyond the scope of science, and creates other problems (see Panspermia theory burned to a crisp: bacteria couldn’t survive on meteorite [also Sugars from space? Do they prove evolution? and Nucleic acid bases in Murchison meteorite? Ed.]).
References and notes
- Parry, W., Possible key to life’s chemistry revealed in 50-year-old Experiment, livescience.com, 21 March 2011. Return to text.
- Johnson, A.P., The Miller Volcanic Spark Discharge Experiment, Science 322(5900):404, 17 October 2008 | doi:10.1126/science.1161527. Return to text.
- Parker, E.T. et al., Primordial synthesis of amines and amino acids in a 1958 Miller H2S-rich spark discharge experiment, Proceedings of the National Academy of Sciences 108(14):5526–5531, 5 April 2011 | doi:10.1073/pnas.1019191108. Return to text.
- Trail, D. et al., The oxidation state of Hadean magmas and implications for early Earth’s atmosphere, Nature 480:79–82, 01 December 2011 | doi:10.1038/nature10655. Return to text.
- Setting the stage for life: Scientists make key discovery about the atmosphere of early earth, sciencedaily.com, 30 November 2011. Return to text.
Forgive my ignorance, but If the experiments were supposed to show that life could evolve from one compound into these amino acids. Why didn't they just leave the hydrogen on its own and let evolution take over? If life started out in this scenario surely it would happen under observation without any interference. I realize that the scientists were trying to reCREATE the conditions they presumed were present on the early earth. But in the act of controlling and initiating the experiment aren't they just becoming a Creator rather than an observer?
That's a fair question. The answer likes in how much investigator interference is justifiable in a genuine evolutionary simulation. See discussion in When is “Intelligent intervention” acceptable?
While it is far fetched to hope that abiogenesis occurred (750,000 years after earth's formation), let's say for a moment that it did. In order for it to proliferate, the informational programming would also have had to spontaneously arisen and inserted itself into the newly contrived cell. It seems to me that this is much less likely than the chemicals managing to arrange themselves into the correct pattern in the first place.
I heard Carl Sagan in his illustrious Cosmos series allude to the notion that some organic matter managed to form itself into some primitive cell that could make "crude" copies of itself. And not only did it happen here (on earth) but must also have happened all over the universe. Even when I believed in evolution, I couldn't bring myself to imagine it could happen twice in one universe.