So, archaea are apparently the topic of the week. While I wrote here about the pathogenic potential of some species of these organisms, a new essay in Nature and a new review in Science focus more on their evolution (and the evolution of the other two domains of life) than any health application.
In the essay mentioned, Norman Pace discusses the eukaryote/prokaryote dichotomy. Currently the archaea are classified as prokaryotes since they, like bacteria, lack a true nucleus. However, molecular sequence analysis has shown that the archaea and eukaryotes are actually more closely related to each other than either group is to bacteria (see figure, from Pace’s Nature essay). As such, nomenclature that places the bacteria and archaea together into a group is misleading.
(Continued at Aetiology)