Molecule sparks origin-of-life debate
By John Travis
What were the first genes made of? Many investigators believe that life’s initial genetic material was ribonucleic acid (RNA) instead of its current choice, deoxyribonucleic acid (DNA) (SN: 5/6/95, p. 279). While evidence for this RNA-world hypothesis has grown, some scientists have questioned whether nucleic acids with a backbone of ribose, or any other sugar molecule, would be stable enough to survive the harsh conditions of early Earth.
Noted origin-of-life investigator Stanley L. Miller of the University of California, San Diego and two colleagues have now offered evidence that peptide nucleic acid (PNA), a more stable alternative to RNA, may have existed during the world’s primordial days. In the early 1990s, scientists created this DNA mimic by combining nucleic acids with a protein backbone. Not long after, Peter E. Nielsen of the University of Copenhagen suggested that PNA might have preceded its less stable relative, RNA, as life evolved.