Is Homochirality a Problem for the Origin of Life?
Question of the Week: Atheists keep telling me that homochirality is not a problem for naturalistic models for life’s origin. How do you respond?
My Answer: All living cells contain proteins, DNA, and RNA. Without proteins, DNA, and RNA physical life is not possible. Proteins are long chains of amino acids and DNA and RNA molecules are long chains of nucleobases. Ribose sugars are required to link together the nucleobases.
Proteins cannot be assembled unless all the amino acids are either 100% left-handed or 100% right-handed. Similarly, RNA and DNA molecules cannot be assembled unless all the ribose sugars are either 100% left-handed or 100% right-handed. Homochirality is where all the chiral molecules in a sample manifest a single-handed configuration.
At the 2017 ISSOL (International Society for the Study of the Origin of Life) conference at the University of California San Diego, which both Fazale Rana and I attended, it was acknowledged by all speakers who addressed homochirality that it was a huge problem for the origin of life. Under highly controlled laboratory conditions, as opposed to real-life naturalistic conditions, biochemists are able to preferentially destroy right-handed amino acids at a faster rate than left-handed amino acids. By this means, in a few of the many experiments conducted, samples that were 80% left-handed were achieved. However, when the biochemists extrapolated their results, they discovered that 100% of the amino acid samples would be destroyed long before homochirality would ever be achieved.
• For more on the homochirality problem see the book by Fazale Rana and me, Origins of Life
• Also, see these free online articles: “Homochirality: A Big Challenge for the Naturalistic Origin of Life,” and “Natural Source of Life’s Homochiral Molecules?”