The scientists were astonished, and quickly turned their attention to other methanogens. The genetic pattern held: The rRNA signatures of the methanogens were distinct from those of eukaryotes and bacteria. Woese concluded that the methanogens were not bacteria.
Wolfe recalled, When Carl said they werent bacteria, I said: Of course they are bacteria! They look like bacteria! They have this prokaryotic morphology and cell structure.
But when Wolfe saw how the sequence data fell into discrete groups, with all the methanogens in a category of their own, I became a believer, he said.
Their findings were published in the Proceedings of the National Academy of Sciences in October 1977. The papers three-sentence abstract stated simply that the methanogens constitute a distinct phylogenetic group only distantly related to bacteria.
A second PNAS paper, published the following month by Woese and Fox, outlined the evidence that there were three rather than two superkingdoms, or domains, of life.
There was general amazement and feeling that something great had been discovered among the physical scientists, Woese said.
Many microbiologists and other life scientists were unwilling to accept the new classification scheme, however. They continued to see the archaea as a highly differentiated offshoot of the bacterial line.
In 2003, Woese won the $500,000 Crafoord Prize in Biosciences for his discovery of this third domain of life. The prize, given by the Royal Swedish Academy of Sciences, marks accomplishments in scientific fields not covered by the Nobel Prizes in sciences, which the academy also selects.
Controversy over the work continued, however. Some scientists described the 1977 announcement of a third domain as an achievement comparable to that of the discovery of a new continent. Others discounted the idea as a fantastic hypothesis based on a limited and unreliable
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign