Woese

Carl R. Woese was an American microbiologist and biophysicist whose use of molecular sequence data transformed the study of evolutionary relationships among living organisms. He pioneered the use of ribosomal RNA sequences, particularly the small subunit (16S/18S) rRNA, as a basis for constructing the tree of life, arguing that genetic data provide a more objective framework for taxonomy than traditional, phenotype-based methods.

In 1977, Woese and his collaborators identified a distinct group of microorganisms based on their rRNA sequences, which did not fit within the then-recognized Bacteria. He and colleagues proposed the existence of a separate primary group, later named Archaea. This lineage, often initially described as Archaebacteria, revealed a fundamentally different kind of prokaryote that inhabited a wide range of environments and displayed unique molecular features.

In 1990, Woese and colleagues proposed the three-domain system, organizing all cellular life into Archaea, Bacteria, and Eukarya. This framework refocused the study of evolution, highlighting deep divisions in life’s history and guiding subsequent research in microbiology, comparative genomics, and evolutionary biology.

Woese spent much of his career at the University of Illinois at Urbana-Champaign, where his pioneering work on molecular phylogenetics influenced modern biology. He was elected to the National Academy of Sciences and received several honors, including the National Medal of Science. His work remains foundational to our understanding of microbial diversity and the early evolution of life. He passed away in 2012, leaving a lasting impact on biology.