Field of Science

Banning the word "prokaryote"

Here I am at the the American Society for Microbiology annual meeting which is being held in Toronto. As Larry Moran has already pointed out, there are a few of us bloggers that are getting together with him while we are here. This should be great.

My first day (actually, part day) was capped off with a really fun, but in many ways maddening, lecture from Norman Pace. Norm was on my PhD committee, and it was the first time I had seen him for 12 years. The talk was wonderfully vintage Norm—even some of the phrases were the same as I remembered. That's not to say that the talk was at all tired. Norm is so fun to see in the spotlight; in this case, he had a big and well-deserved stage on which to perform! As an historical aside, Norm's class on the biochemistry of nucleic acids at Indiana University was the only biochemistry course that I ever took that started by reference to a rRNA tree of life. Norm has been ahead of the curve for a long time...

A major—and provocative—theme of Norm's talk is that we microbiologists should strike the word "procaryote" (or prokaryote, as I prefer to spell it) from our vocabulary. This is not a trivial matter for the microbiologists in attendance, both from practical and intellectual points of view. This part of his talk followed directly from his recently published piece in Nature entitled "Time for a change." (2006) 441:289. I happen to strongly disagree with Norm on this point and am much more aligned with the views subsequently published by Martin & Koonin entitled "A positive definition of prokaryotes" in Nature (2006) 442: 868. Although I'm too short on energy to do so now, I'll try to decipher my notes and give a more clear account of what Norm said (and my reactions to it) in the coming days.


  1. I was burned out today before Pace's talk; too bad I missed it, sounds like a good one. I wrote a bit about his paper here and wanted to hear him expand upon it, too, but after about 9-10 hours even I need a break from micro.

  2. Although I'm too short on energy to do so now, I'll try to decipher my notes and give a more clear account of what Norm said (and my reactions to it) in the coming days.

    Please do. For us non-micros that's an interesting question/issue and I'd like to learn more about it.

  3. In addition to Tara's previous post on this topic (above), Elio over at Small Things Considered also previously posted on this.

  4. I missed the talk as well. I remember reading the views of Woese a few years ago in this artice. I like Elio's position in the post you linked to especially in the light of the Martin and Koonin argument for a positive definition.

  5. Hi John, First, my apologies for not attending the bloggers' dinner in Toronto. I am about to post a Talmudic Question that asks: "What if there were more than three domains of life?" One of the implications is that if the new ones consisted of anucleated organisms, we would have to refer to them by a list of names.

    I greatly admire your blog.

  6. I used to hang around Carl Woese a lot, so this argument is not new to me. It is easy to get so caught up in the semantic arguments that you miss the point.I think that the key point is understanding the differences (and similarities) between the three domains of life. The concept of a nuclear membrane (or not) is important, but not MORE important than other properties of cells. Hence, if people simply used the term "prokaryote" to refer to the lack of a nuclear membrane, it wouldn't be an issue. The problem is that the word prokaryote carries such historical baggage that people make inappropriate inferences about organisms from this term.

  7. I greatly enjoyed Norm's talk. Sitting there with John listening to Norm reminded me of our student days at Indiana University and the excellent faculty we had.

    I do not like the term prokaryotes, and avoid using it myself because:
    1. I find little usefulness in discussing the bacteria and archaea as a single group. Do we need a special term for archaea plus eukaryotes and for eukaryotes plus bacteria?
    2. The term prokaryotes confuses my students. I am invariably asked if it includes both the bacteria and the archaea and students then assume that archaea are essentially like bacteria. This leads to great confusion, particularly when discussing gene expression where archaea are more like eukaryotes than prokaryotes.

  8. If one is explicit that the term indicates a structural grade rather than a phylogenetic clade (but I repeat myself), then the term "prokaryote" is still very useful, especially in teaching. Similar terms include algae, bryophytes, fishes, reptiles, pseudocoelomates, etc.

  9. Does Norm propose banning the word "tag"? I hope not - because I hereby tag you.


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