Notable quotes from this article published in Scientific American 4/97
" In the summer of 1996 a large collaboration of scientists deciphered the full sequence of units, or nucleotides, in every gene of Methanococcus jannaschii--a methane-producing extremophile that thrives at temperatures near 85 degrees Celsius. The results strikingly confirmed the once ridiculed proposal that life consists of three major evolutionary lineages, not the two that have been routinely described in textbooks"...
..."That M. jannaschii has characteristics of bacteria and eukarya but also has marked differences suggests that archaea and the other two lineages have a common distant ancestor. Partly because many archaea and some bacteria are adapted to the conditions widely believed to have existed on the early earth--especially high heat and little or no oxygen--a majority of investigators suspect that those two groups appeared first, diverging from a common ancestor relatively soon after life began. Later, the eukarya split off from the archaea. Further support for this scenario can be seen in the evolutionary tree itself:"