Is Adenine Additive?
A paper in PNAS argues that adenine can form in plausible prebiotic conditions.1 Does this add to the story of chemical evolution leading to life on Earth?
Some chemists at the University of Georgia explored the chemical steps necessary to form adenine (one of the bases used in DNA). Adenine has been found in extraterrestrial environments. They found that ammonia or water can act as a catalyst to get the incipient molecule past some of the energy hurdles of ring formation. After describing their investigation in detail, they remarked, “Finding a viable, thermodynamically feasible, step-by-step mechanism that can account for the formation of adenine did not prove to be easy.” Nevertheless, they felt that their success will motivate others to find how the remaining DNA bases could have formed naturally.
The authors went far beyond merely elucidating the mechanism behind the formation of adenine in meteorites or interstellar space. They explicitly claimed that it contributes to understanding how life originated:
Our report provides a more detailed understanding of some of the chemical processes involved in chemical evolution, and a partial answer to the fundamental question of molecular biogenesis. Our investigation should trigger similar explorations of the detailed mechanisms of the abiotic formation of the remaining nucleic acid bases and other biologically relevant molecules.
In fact, the first line in the paper is, “How did life begin? The presence of biomolecules was a prerequisite, but the origin of even the simplest of these remains a fascinating but unsolved puzzle.” Understanding the origin of adenine, to them, thus would constitute progress in the story of life’s origin.
1. Roy, Najafian and Schleyer, “Chemical evolution: The mechanism of the formation of adenine under prebiotic conditions,” Proceedings of the National Academy of Sciences USA, published online before print October 19, 2007; 10.1073/pnas.0708434104.
Did you notice the logical trick? It is one question to account for the observed extraterrestrial formation of a chemical, but quite another to suggest it is relevant to the origin of life. This presupposes naturalism—the very question that ought to be up for debate.
If that is what they wanted to do (prove naturalism) they should have stated their presuppositions and goals objectively, but they didn’t. They snuck their presuppositions into the paper as if nobody would notice or care. Well, we care. We are not going to let them suggest that explaining adenine has anything to do with supporting philosophical naturalism, any more than would explaining water, dust, plasma or the laws of nature. This is like a Democrat claiming, “We explained the mechanism of voting machines, therefore President Bush stole the election.” Voters used voting machines, but that has no bearing on the very different question of how they were used. They might as well explain the chemical pathway of a component of a computer chip as support for the belief that computer software wrote itself. Adenine is a substrate used in life for coded messages. Just like understanding the chemistry of paper and ink says nothing about the origin of the message in a book, understanding the chemistry of adenine says nothing about the genetic code. Is a cathode-ray tube aware that Survivorman is playing through its electrons? Did the CRT organize itself for this purpose? Neither does adenine form for the purpose of self-organizing into a living system.
We must not allow materialists to invoke the chemistry lab as support for their philosophy. That is called begging the question. Only by assuming that life is no more than chemistry can they make that connection.