How did life on Earth begin? Does an experimenter’s intervention reveal the “hand” that made life?
Fuz Rana and I attended the 2002 International Society for the Study of the Origin of Life (ISSOL) Conference held June 30–July 5 in Oaxaca, Mexico. There we heard the atheist/agnostic chemist Robert Shapiro publicly comment on the laboratory simulation of one of the more complex chemical reactions known to be critical for any origin-of-life model. Shapiro complemented the scientific team for their brilliant lecture and amazing achievement, but pointed out how much intelligent intervention and design were needed to produce their outcome. He added that if his peers could not produce chemical outcomes known to be vital for any conceivable origin-of-life model without far less experimenter interference then they simply were proving that the origin of life required an intelligent designer. Fuz and I heard a whole row of origin-of-life chemists behind us loudly whisper, “Heaven forbid.”
Sixteen years later chemist Clemens Richert published an article in Nature Communications in which he more fully articulated Shapiro’s point.1 He began by explaining that the reputed goal of experimental biochemists doing origin-of-life research is “to re-enact what may have happened when life arose from inanimate material.”2 Richert pointed out, though, that such reenactments are unrealistic if one or more human interventions are required.
Reproducibility and Intervention
One such intervention that inevitably occurs arises from the experimenters’ desires that their results be reproducible by other biochemists. If their results cannot be reproduced, there is little, if any, likelihood that they will be published in any reputable science journal. This need for reproducibility forces the biochemists to begin with known quantities of pure chemicals. However, such fixed, pure quantities are unrealistic in any conceivable natural prebiotic scenario. The second law of thermodynamics inevitably introduces mixtures of structurally related but chemically interfering molecular aggregates.
Furthermore, to be relevant to any conceivable natural origin-of-life scenario the experiment must not involve any human intervention after the start of a reaction. There cannot be any addition or subtraction of chemicals during the reaction. The reaction must be allowed to unfold and samples drawn only after the reaction is completely finished.
Even when these strictures are rigorously obeyed not-so-subtle human interferences can and do occur. For example, in the famous Miller-Urey experiment3 where researchers claimed to synthesize amino acids from sparking a mixture of water, ammonia, methane, and hydrogen in an enclosed flask, the experiment was performed about 200 times. In only one of those 200 trials were five amino acids generated, at a total concentration of two percent where nearly all of that two percent was glycine, the simplest amino acid. Moreover, the starting conditions were irrelevant. In any natural scenario, there would either be oxygen or ultraviolet radiation present and either would have halted the reaction. Also, the concentration of ammonia in any natural scenario would be far lower than what was present in the flask and inevitably there would be many more chemicals present than just water, ammonia, methane, and hydrogen.
The Miller-Urey experiment is a classic example of multiple human interventions where the experimenters thought there were none. Today, the Miller-Urey experiment and many others like it are widely recognized as irrelevant to the origin-of-life on Earth or on any other planetary body.
Intervention Required for Amino Acid Joining
For more complex reactions than the Miller-Urey experiment, such as the joining together of bioactive amino acids to construct short protein segments, repeated interventions by the experimentalists have proved necessary. Each step needs a specific chemical environment or set of conditions to occur at high yields. Often, a subtraction reaction needs to occur simultaneously with an addition reaction where both must occur at specified rates.
In the case of joining together amino acids, the amino acids must all be homochiral (all left-handed in their molecular configuration). In the naturally occurring random mixture of left-handed and right-handed amino acids no such joining together occurs. A similar chirality limitation occurs for joining together nucleobases to make short strands of RNA or DNA. To join nucleobases together requires ribose sugars as chemical bridges and the ribose sugars must all be right-handed in their configuration. Outside of laboratories and living systems or the decay products of living systems, ribose is extremely rare, almost always undetectable, and always results as random mixtures of left- and right-handed configurations.
In living cells, biochemical synthesis usually occurs through catalyzed reactions by different enzymes where each enzyme requires a distinct, specified microenvironment at its active site for the reaction to run. In simulating an enzyme-free prebiotic scenario, experimenters find that they must employ multiple, highly ordered chemical steps that involve precipitation, crystallization, purification, and drastic changes in the chemical conditions from one synthesis step to the next. Even then, success rarely occurs.
Toward the end of his article Richert takes to task the now popular experiments of unending cycles of hydration and dehydration and/or cooling and heating. Richert points out, for example, that for cooling and heating cycles to be productive requires repeated specified transitions in a single locale from arctic to volcanic conditions then back to arctic within just hours or a few days. Such requirements, he understates, seem unrealistic for natural scenarios.
Intervention and the Hand of God
In his article, Richert coined a phrase for the experimenter intervention. He called it “the Hand of God dilemma.” His point is that experimenter intervention is akin to claiming that God did it. In saying this, he admits that “most of us [origin-of-life researchers] are not comfortable with the idea of divine intervention in this context.”3
Richert, nevertheless, makes a strong appeal to his fellow origin-of-life researchers. So as not to deceive researchers in other disciplines, and especially the lay public, or to exaggerate their successes to their research peers, Richert recommends that his peers reveal the level of experimenter intervention. In their publications, they should state as accurately as possible how many times and exactly when and where in their experiments they commit the Hand of God dilemma.
Having been to several origin-of-life conferences and having read hundreds of origin-of-life research papers, I think if Richert and his peers followed through on his recommendation, the number count of how many times the Hand of God dilemma has been committed per published origin-of-life experiment easily would exceed an average of a dozen times. If that’s the case, then the lay public, scientists in other disciplines, and maybe even origin-of-life researchers themselves will recognize and acknowledge that God, not a set of unguided natural processes, created the first life on Earth.