How to beat the United States in gene editing? A research team from Peking University and the Chinese Academy of Sciences had struggled with this question for three years, with no results. Then they decided to draw inspiration from an ancient woodwork tradition and cut DNA like wood. It led to a gene-editing tool with unprecedented efficiency. In the Chinese mortise-and-tenon joint technique known as sunmao, no nails or glue are used. Instead, a protruding “tenon” on one piece fits securely into...