TITLE:  Triumph of the Archaea
      AUTHOR:  ZIMMER, CARL
     JOURNAL:  Discover
    CITATION:  February, 1995, 16: 30-31.
        YEAR:  1995
    PUB TYPE:  Article
 IDENTIFIERS:  BACTERIA; PROKARYOTES; DNA; EUKARYOTES; NUCLEUS; WOESE/CARL; 
               ARCHAEA
    ABSTRACT:       Before 1977, life was basically divided into two 
               categories: bacteria and everything else. The bacteria, also 
               known as prokaryotes, had DNA that floated free in the cell, 
               whereas the eukaryotes--such as fungi, plants and animals--
               had their DNA in a nucleus. In 1977, Carl Woese, a 
               microbiologist at the University of Illinois, showed that 
               there was actually a third type of life: a group of 
               prokaryotes he called the archaea. Not only are the archaea 
               genetically distinct from the other prokaryotes--which Woese 
               renamed eubacteria or "true" bacteria--they are more closely 
               related to humans than they are to E. coli, and other 
               bacteria.
                    It is now believed that the archaea and eubacteria 
               diverged from a common ancestor nearly 4 billion years ago, 
               soon after the origin of life. Only much later on, did the 
               ancestors of today's eukaryotes split off from the archaea. 
               Recently, Hot Springs in Yellowstone National Park have 
               revealed very high levels of archaea diversity, including a 
               pair of organisms that are the most primitive forms of life 
               alive today. Meanwhile, other strains of archaea have been 
               discovered leading perfectly contented lives in the cool, 
               oxygen-rich ocean, in such incredible numbers that they must 
               play an important ecological role. Researchers will now have 
               to prove whether or not archaea are the most common organisms 
               on Earth.