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Researchers Overlook Toxic Products in Origin-of-Life Experiments

Photo credit: Beth Jnr via Unsplash.

A natural process to explain the origin of life must begin with production of its basic building blocks: amino acids, nucleotides, carbohydrates, and lipids. A new and humorous animated video, “Long Story Short, The Origin of Life; Part 1: The Basic Building Blocks,” emphasizes three ways that origin-of-life researchers dismiss reality when claiming that the building blocks of life can be produced by natural causes. I wrote about the video here last week when it premiered, reviewing the first of those ways. Now I will turn to the second. 

Production of Interfering or Toxic Products

Origin-of-life researchers stop their reactions at optimal times, and scan through the products of their reactions with sensitive high-tech equipment to find trace amounts of the product they seek. When the product is located, they claim success, publish a paper, and move on. But what about the other products of the reaction? And what if the reaction was not artificially stopped, but was allowed naturally to continue?

Agnieszka Wołos and colleagues built a computer simulation called “Allchemy” to simulate chemical reactions in a prebiotic world. They started with just six pure ingredients (H2O, N2, HCN, NH3, CH4, and H2S). After only seven rounds of chemical reactions among the reagents, the simulation produced 36,603 different molecules that are not found in living organisms and only 82 different molecules that are found in living organisms. Thus, 99.776 percent of the molecules that they produced were not biotic. This is not only a problem of dilution of the desired (biotic) molecules, but many of the undesired molecules will cross-react, block, or otherwise destroy the molecules that are desired for life. Imagine if a concrete mixer contained only 0.224 percent of the items needed to make concrete (limestone, clay, gypsum, gravel, sand, and water) and 99.776 percent random items that are not found in concrete (e.g., toothbrushes, basketballs, Cheetos, cockroaches, and some random items that are detrimental to concrete production: sugar and sulfuric acid). In the Wołos study, this very unfavorable ratio of non-biotic to biotic molecules occurred, as I said, after only seven rounds of chemical reactions to produce rather simple molecules. With more rounds of reactions and the addition of other biologically relevant starting molecules such as phosphate, the situation grows exponentially worse. As stated by the authors:

[B]ecause the masses of molecules like ATP, ADP or dinucleotides are high (above 400 g/mol), creating them from very basic substrates (HCN, H2O, CH4, N2, H3PO4) takes 9-13 synthetic generations within which extremely large numbers of other, not-very-interesting molecules are created…

A. Wołos et al., “Synthetic connectivity, emergence, and self-regeneration in the network of prebiotic chemistry,” Science (2020) 

Only a Computer Simulation?

Some may be thinking that this is only a computer simulation, not reality. However, as a general principle, prebiotic processes will always produce vast arrays of molecules that fill the chemical “space” of all possible molecular configurations, whereas life is built upon a relatively small set of very select molecules. The chemical constituents of carbonaceous chondrite meteorites provide a confirmatory reality check. These meteorites contain organic compounds produced by purely natural processes in outer space. The Murchison meteorite contained 

tens of thousands of different molecular compositions, and likely millions of diverse structures…[which] suggests that the extraterrestrial chemodiversity is high compared to terrestrial relevant biological and biogeochemical-driven chemical space

Schmitt-Kopplin, P., et al., “High molecular diversity of extraterrestrial organic matter in Murchison meteorite revealed forty years after its fall,” Proc Natl Acad Sci U S A, 2010. 107(7): 2763–2768

Origin-of-life researchers conveniently overlook this unpleasant reality. They artificially stop reactions when production of the desired product is maximized and they maintain laser-focus on detecting only their desired product while ignoring the implications of the vastly predominant undesired molecules that they produced.

For those who want to learn more, my recent book, The Stairway to Life, gives a list of 12 required steps to advance from chemistry to the simplest forms of life. The production and concentration of the basic building blocks is only the first of the 12 required steps.