17 Nature Is Cleverer Than We Are

An Oxford-educated chemist who worked on the origins of life, Leslie Orgel (figure 17.1, right) was a colleague at the Salk Institute for many years and one of the smartest scientists I have ever met. Discussions with him at faculty lunch on Fridays were always fascinating. The origin of life goes back billions of years to a time when the earth was so different from today that it would not support life as we know it. Conditions were harsh, and there was little oxygen in the atmosphere. Bacteria were preceded on the earth by archaea, but what came before archaea? DNA is common to all cells today, but what came before DNA? In 1968, Leslie Orgel and Francis Crick speculated that RNA, which is derived from DNA in cells, might have been the precursor, but this would require RNA to self-replicate. Evidence for this possibility was found in the form of ribozymes, RNA-based enzymes that can catalyze RNA reactions,
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and today most researchers in the field believe it is quite possible that all life descended from an earlier “RNA world.”
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But where did RNA come from? Unfortunately, we have little evidence from that period to go on.