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HOME > PAST ISSUE > March-April 2009 > Article Detail

FEATURE ARTICLE

The Origin of Life

A case is made for the descent of electrons

James Trefil, Harold J. Morowitz, Eric Smith

Figure 1. Prebiotic Soup canClick to Enlarge ImageAs the frontiers of knowledge have advanced, scientists have resolved one creation question after another. We now have a pretty good understanding of the origin of the Sun and the Earth, and cosmologists can take us to within a fraction of a second of the beginning of the universe itself. We know how life, once it began, was able to proliferate and diversify until it filled (and in many cases created) every niche on the planet. Yet one of the most obvious big questions—how did life arise from inorganic matter?—remains a great unknown.

Our progress on this question has been impeded by a formidable cognitive barrier. Because we perceive a deep gap when we think about the difference between inorganic matter and life, we feel that nature must have made a big leap to cross that gap. This point of view has led to searches for ways large and complex molecules could have formed early in Earth’s history, a daunting task. The essential problem is that in modern living systems, chemical reactions in cells are mediated by protein catalysts called enzymes. The information encoded in the nucleic acids DNA and RNA is required to make the proteins; yet the proteins are required to make the nucleic acids. Furthermore, both proteins and nucleic acids are large molecules consisting of strings of small component molecules whose synthesis is supervised by proteins and nucleic acids. We have two chickens, two eggs, and no answer to the old problem of which came first.

In this article we present a view gaining attention in the origin-of-life community that takes the question out of the hatchery and places it squarely in the realm of accessible, plausible chemistry. As we see it, the early steps on the way to life are an inevitable, incremental result of the operation of the laws of chemistry and physics operating under the conditions that existed on the early Earth, a result that can be understood in terms of known (or at least knowable) laws of nature. As such, the early stages in the emergence of life are no more surprising, no more accidental, than water flowing downhill.

The new approach requires that we adopt new ways of looking at two important fields of science. As we will see below, we will have to adjust our view of both cellular biochemistry and thermodynamics. Before we talk about these new ideas, however, it will be useful to place them in context by outlining a little of the history of research on the origin of life.





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