Carl Woese Born 15 Jul 1928
American microbiologist who recognized the existence of the organisms Archaea as a third domain of life, distinct from the previously recognized two domains of bacteria, and life other than bacteria. On 2 Nov 1977, his identification of methanogens, a form of life dating back some 3.5 billion years, was reported from the University of Illinois. Woese had long studied the evolutionary track of DNA and RNA. In 1976, he was approached by his colleague Ralph Wolfe, who presented a group of methane producing organisms. Woese studied their RNA and recognized their lack of the entire oligonucleotide sequences. Methanogens are found in oxygen-deficient environments, and mostly obtain their energy by reducing CO2 and oxidizing hydrogen, and releasing methane.
(From today in Science History)
See his paper On the Evolution of Cells (2002) for an overview of how life may have developed before natural selection could take place, and how
“…there would come a stage in the evolution of cellular organization where the organismal genealogical trace (recorded in common histories of the genes of an organism) goes from being completely ephemeral to being increasingly permanent. This point in evolution, this transition, is appropriately called the ‘‘Darwinian Threshold.’’ On the far side of that Threshold ‘‘species’’ as we know them cannot exist. Once it is crossed, however, speciation becomes possible. The Darwinian Threshold truly represents the Origin of Species, in that it represents the origin of speciation as we know it.“