This paper, coauthored with a young physicist named Kalin Vetsigian, appeared in 2006, bringing forward the subject with which Woese had grappled in his 1967 book. It offered the radical proposition that the universality of the code—all creatures using the same three-letter DNA combinations to call in the same amino acids—reflects a dynamic evolutionary process during the early history of life, not a “frozen accident” traceable to happenstance in one small population of universal ancestors,
