The RNA World Theory of Life's Origin Is Running Into Trouble
Did Life Begin in an RNA World?
The RNA world hypothesis holds that life began with self-copying RNA molecules that could mutate and evolve, solving the chicken-and-egg problem of DNA and proteins. But Gerald Joyce's lab found that mutations in evolving ribozymes tend to destroy their catalytic ability, and spontaneous assembly has only produced tiny fragments of 10 to 15 nucleotides. Philipp Holliger's QT45, a 45-nucleotide self-copying RNA, offers some hope, yet questions remain about whether such a world could ever be truly alive.
It's not clear that an RNA world would be truly alive. Life isn't just about self-replicating carriers of genetic information — it takes more ingredients, in particular the existence of some form of metabolism to harvest energy from the environment and use it to make useful molecules.