Theoretical origin of life: Miller-Urey all wrong (Introduction)

by David Turell @, Tuesday, November 23, 2021, 18:09 (11 days ago) @ David Turell

Further repeat studies with new findings:

https://www.realclearscience.com/2021/11/23/what_the_famous_miller-urey_experiment_got_...

"The experiment mixed water and simple gases — methane, ammonia, and hydrogen — and shocked them with artificial lightning within a sealed glass apparatus. Within days, a thick colored substance built up at the bottom of the apparatus. This detritus contained five of the basic molecules common to living creatures. Revising this experiment over the years, Miller claimed to find as many as 11 amino acids. Subsequent work varying the electrical spark, the gases, and the apparatus itself created another dozen or so. After Miller’s death in 2007, the remains of his original experiments were re-examined by his former student. There may have been as many as 20-25 amino acids created even in that primitive original experiment.

"The Miller-Urey experiment is a daring example of testing a complex hypothesis. It is also a lesson in drawing more than the most cautious and limited conclusions from it.

"In the years following the original work, several limitations curbed excitement over its result. The simple amino acids did not combine to form more complex proteins or anything resembling primitive life. Further, the exact composition of the young Earth did not match Miller’s conditions. And small details of the setup appear to have affected the results. A new study published last month in Scientific Reports investigates one of those nagging details. It finds that the precise composition of the apparatus housing the experiment is crucial to amino acid formation.

***

"One of the elements of art in science is to divine which of innumerable complexities matter and which do not. Which variables can be accounted for or understood without testing, and which ones can be cleverly elided by experimental design? This is a borderland between hard science and intuitive art. It is certainly not obvious that glass would play a role in the outcome, but it apparently does.

***

"The authors of the new work performed just such a single-variable test. They ran the entire Miller-Urey experiment multiple times, varying only the presence of silicate glass. The runs performed in as glass vessel produced one set of results, while those using a Teflon apparatus produced another.

"Systematically marching through each potential variable, one at a time, might be called “brute force.” But there is art here too, namely, in deciding which single variable out of many possibilities to test and in what way. In this case, we learned that glass silicates played an important role in the Miller-Urey experiment. Perhaps this means that silicate rock formations on the early Earth were necessary to produce life. Maybe."

Comment: a brilliant experiment for its time, but concludes nothing. The author forgets to note that the amino acids produced were both right and left handed, and proteins for life are left handed.


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