Research conducted by the CBA group is deeply rooted in the biology of Archaea, which are microorganisms discovered in 1977 by Carl Woese. In the tree of life, the Archaea constitute a new domain in its own right, next to the Eukarya domain and the Bacteria domain. A key feature of these Archaea consists of their particular natural environments which often includes one or more condition(s): temperature, pH, salinity, anaerobic and barometric pressure. Archaea therefore extend life in environments where no other organism is capable of surviving. To better understand the evolutionary mechanisms that led to the existence of Archaea, we use a multidisciplinary approach involving genetics, genomics, bioinformatics and biochemistry. Three main topics are currently being pursued: the evolution and genome dynamics in the Archaea Thermococcales; the characterization of the KEOPS complex and prokaryotic genomes bioinformatics.