E-Mail Credit: The University of Queensland Scientists now better understand early bacterial evolution, thanks to new research featuring University of Queensland researchers. Bacteria comprise a very diverse domain of single-celled organisms that are thought to have evolved from a common ancestor that lived more than three billion years ago. Professor Phil Hugenholtz, from the Australian Centre for Ecogenomics in UQ's School of Chemistry and Molecular Biosciences, said the root of the bacterial tree, which would reveal the nature of the last common ancestor, is not agreed upon. "There's great debate about the root of this bacterial tree of life and indeed whether bacterial evolution should even be described as a tree has been contested," Professor Hugenholtz said.