What evidence led scientists to develop the three domain system?

The development of the three-domain system was primarily based on molecular evidence, particularly the analysis of ribosomal RNA (rRNA) sequences. In 1977, Carl Woese and his colleagues discovered significant differences in the 16S rRNA sequences between certain prokaryotes, leading to the identification of Archaea as a distinct group separate from Bacteria. This molecular data revealed that the genetic differences between Archaea and Bacteria were as significant as those between Bacteria and Eukarya, prompting the reclassification of life into three domains: Archaea, Bacteria, and Eukarya.