For a naturalistic explanation for the origin of life to become a possibility, some nonbiological source of five-carbon sugars must be found
Compulsory features for the replicating molecules of life (DNA and RNA) include five-carbon sugars, namely deoxyribose for DNA and ribose for RNA. These sugars form the backbone of DNA and RNA. Thus, for a naturalistic explanation for the origin of life to become a possibility, some nonbiological source of five-carbon sugars must be found.
For several decades scientists have scoured both the Earth and the universe in a fruitless search for natural five-carbon sugars. The closest they have come is the discovery of a trace amount of a two-carbon sugar (glycolaldehyde) in just one dense interstellar molecular cloud near the center of the Milky Way Galaxy.1 The fractional abundance compared to the most common interstellar molecule (H2) was only 5.9 x 10-11.
Meanwhile, under controlled laboratory conditions biochemists have successfully synthesized small amounts of ribose through what is called the “formose reaction.” The problem is that none of these laboratory synthesis experiments correspond to conditions found in nature.
In a recently published paper in Astrobiology a team of Mexican and American astronomers for the first time made a “sugar” under conditions known to exist in the dense interstellar molecular cloud that resides at the galactic center.2 The sugar they manufactured was the simplest possible sugar, namely, glycolaldehyde. The method of manufacture was the formose reaction and their results are consistent with the extremely tiny amount of glycolaldehyde astronomers found in the molecular cloud at the galactic center.2
Thus, any remaining hope for finding a natural source of five-carbon sugars, at least at an abundance level that would have some significance for the origin of life, is even more firmly dashed than it was before. With no natural chemical pathway for making adequate and stable enough amounts of the necessary sugars, a supernatural explanation for life’s origin must be considered.
- J. M. Hollis et al., “The Spatial Scale of Glycolaldehyde in the Galactic Center,” Astrophysical Journal Letters 554 (June 10, 2001): L81-L85; D. Halten et al., “A Systematic Study of Glycolaldehyde in Sgr B2(N) at 2 and 3 Millimeters: Criteria for Detecting Large Interstellar Molecules,” Astrophysical Journal 639 (March 1, 2006): 237-45.
- Abraham F. Jalbout et al., “Sugar Synthesis from a Gas-Phase Formose Reaction,” Astrobiology (June, 2007): 433-42.