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Chapter 1 : The Archaea: an Invitation to Evolution †
The discovery of the archaebacteria was serendipitous, but not unexpected. In the late 1960s, the author had begun assembling the program for inferring (organismal) genealogical relationships through rRNA sequence comparisons, as the structure of the universal phylogenetic tree was yet to be determined. Molecular evolution had been on the scene for the better part of a decade, and a universal framework within which to study evolution from the molecules on up was needed. The objective in establishing the phylogenetic program, however, was not to refine bacterial taxonomy per se, but to restore an evolutionary perspective/spirit to biology. This time the focus would be on the evolution of the cell itself, in particular, the evolution of its translation mechanism. The walls of the would-be archaeabacteria were not the most important clue, however, for they would turn out to be nonhomologous among themselves. Not only were the phenotypically diverged cousins of the methanogens beginning to show up, but so were the traits common to all archaebacteria. Though reluctant at first, microbiology did eventually come around to accepting the archaea. Molecular reductionism is now spent as a conceptual force and has settled into being a most useful body of technology. Microbial biology in the meanwhile has undergone a conceptual and methodological revolution of its own, freeing itself from its self-inflicted intellectual confinement. The future of biology lies in microbial ecology. Molecular biology is moving in an evolutionary direction-compelled by its own technology.