| A New Domain : In the late 1970s, Dr. Carl Woese spearheaded a study of evolutionary relationships among prokaryotes. Instead of physical characters, he relied on RNA sequences to determine how closely related these microbes were. He discovered that the prokaryotes were actually composed of two very different groups -- the Bacteria and a newly recognized group that he called Archaea. Each of these groups is as different from the other as they are from eukaryotes. These three groups are now recognized as three distinct domains of life. Credits: Berkeley |
