How did you start thinking about this fundamental question at the heart of the discovery of microRNA, about how cells get the instructions to do what they do?

The paper that described this discovery was published in 1993. In the late 1980s, we were working in the field of developmental biology, studying C. elegans as a model organism for animal development. We were using genetic approaches, where mutations that caused developmental abnormalities were then followed up to try to understand what the gene was that was mutated and what the gene product was.