Scientist of the Day - Carl Woese

The place of Archaea in the tree of life, detail of first page of “Interpreting the universal phylogenetic tree," by Carl R. Woese, Proceedings of the National Academy of Sciences, vol. 97(15), p. 8392, 2000 (Linda Hall Library)

Carl R. Woese, an American microbiologist, was born July 15, 1928, in Syracuse, New York. He attended Deerfield Academy, Amherst College, and Yale University, an impressive pedigree for a northeastern lad, and interestingly, never studied microbiology. His PhD was in biophysics, which is quite a different subject; his postdoc was in biophysics; he worked as a biophysicist for General Electric Labs through 1963; and then he was suddenly asked to join the department of microbiology at the University of Illinois, where he began in 1964 and remained for the rest of his career. Clearly somebody saw something, and that somebody had a discerning eye, as Woese would make a fundamental discovery that would revolutionize evolutionary biology.

Carl R. Woese, photograph by Charlie Vossbrinck, 1982, New Yok Times Magazine, Aug. 13, 2018 (nytimes.com)

Most microbiologists and molecular biologists in the late 1960s were trying to figure out how DNA coding works, and especially how the ribosomes in cells go about building proteins using the blueprints carried by messenger RNA. Ribosomes in fact have their own kind of RNA, called rRNA for short, which is non-coding, and this is what Woese chose to study. Every organism has rRNA, and although it differs slightly from species to species, it has great evolutionary stability, meaning it doesn't change much, even over hundreds of millions of years. Woese thought that a tree of life based on variations in rRNA might shed light on the evolution of life in its earliest stages.

At the time Woese began his work, two basic kingdoms of life were recognized: the prokaryotes, which are one-called organisms with no nucleus, basically bacteria; and the eukaryotes, those organisms, both unicellular and multicellular, with nucleated cells. Since bacteria seem simpler, and thus older, Woese studied bacteria. In particular, he chose to study a molecule from bacterial ribosomes that was not too short to be useful or too long to be manageable. It was called 16S ribosomal RNA. He developed techniques, using radioactive markers and electrophoresis, to break up ribosomal RNA and stretch it out into blobs, which he learned how to read, taking many years to learn the language (fifth image).

First paragraph, “Phylogenetic structure of the prokaryotic domain: The primary kingdoms,” by Carl R. Woese and George E. Fox, Proceedings of the National Academy of Sciences, vol. 74(11), p. 5088, 1977 (Linda Hall Library)

One day in June of 1976, Woese was examining the rRNA from what he thought was a methane-producing bacteria, when he realized that the rRNA was all wrong. This wasn't a bacterium – this was something brand new – a new kingdom of life. He found more and more examples over the next year, and he named this new kingdom: Archaebacteria.

Woese announced his discovery of a new kingdom of life in a paper that appeared in late November of 1977 in the Proceedings of the National Academy of Sciences (NAS) (third image). It was noticed, because Woese unwisely allowed NASA and NSF, the supporters of his research, to issue a press release on the day of publication, which was properly interpreted and announced on the front page by the New York Times, but garbled by most of the other newspapers that carried the story. At the time (and perhaps still), it was considered bad form to announce a major discovery by press release, and most of the potential readers of Woese's paper resented that, and consequently took a dim view of Woese's proposal of a third kingdom of life. Giants in the field like Salvador Luria rejected the idea out of hand, and many others did so as well. It took a full 10 years for the idea to begin to find support.

First paragraph, "Towards a natural system of organisms: Proposal for the domains Archaea, Bacteria, Eucarya," by Carl R. Woese, Otto Kandler, and Mark L. Wheelis, Proceedings of the National Academy of Sciences, vol. 87(12), p. 4576, 1990 (Linda Hall Library)

It did not help that Woese was generally disliked by his peers, except for a few close colleagues, and that he lacked communication skills, being unable to explain his ideas to reporters or anyone else. But there was nothing wrong with his evidence – the ribosomal RNA did not lie – and eventually the tide turned. It helped that Woese quit talking about a third kingdom and introduced the word “domain,” as a higher taxon than kingdom. And it also helped that Woese abandoned his original name for the new form of life - Archaebacteria. That was an ill-chosen term, for the whole point was that these were NOT bacteria, but a different and far older form of life. By 1990, in another major paper in the Proceedings of the NAS, the title set things straight: “Towards a natural system of organisms: Proposal for the domains Archaea, Bacteria, Eucarya" (we would now write Eukarya) (fourth image).

An older Carl R. Woese at his light table, with prints of electrophoretic separations of fragments of 16S ribosomal RNA, with which he discovered the existence of the Archaea domain, undated photograph, Carl R. Woese Institute for Genomic Biology, University of Illinois (www.igb.illinois.edu)

Woese never received the Nobel Prize for his discovery of Archaea. It was certainly a prize-worthy achievement, but he made it late in life – he was 49 when his 1977 paper appeared – and he just didn't live long enough, even though he made it to age 84, passing away in 1912. But on any list of scientists who should have been awarded a Nobel Prize, Woese is right at the top. David Quammen, in his wonderful book, The Tangled Tree: A Radical New History of Life (Simon & Schuster, 2018) called Woese: “the most important biologist of the 20th century that you’ve never heard of,” and I think he was right in that assessment. I highly recommend Quammen’s book if you would like to know more about Woese and the search for the molecular origin of life.

First paragraph, “Interpreting the universal phylogenetic tree," by Carl R. Woese, Proceedings of the National Academy of Sciences, vol. 97(15), p. 8392, 2000 (Linda Hall Library)

Woese’s principal memorial is the new "tree of life" diagram that is now ubiquitous in textbooks and on Wikipedia. No longer recognizable as a tree, it resembles a bramble, with the archaea, bacteria, and eukaryotes emanating from a central point. We show you Woese’s own drawing of the tree of life, as it appeared in a third paper in the Proceedings of the NAS in 2000, both as a detail (first image) and in context (last image).

William B. Ashworth, Jr., Consultant for the History of Science, Linda Hall Library and Associate Professor emeritus, Department of History, University of Missouri-Kansas City. Comments or corrections are welcome; please direct to ashworthw@umkc.edu.