Saturday, September 12, 2009

Butterfly Sex and Wild Science: The Curious Tale of Caterpillars and Velvet Worms

Lots of people have peculiar ideas. For example, belief in the Loch Ness monster, alien abduction, and the chupacabra, are widespread. However, most rational scientists don’t expect that their as yet unsupported wild notion will find its way into the pages of a highly prestigious international scientific journal. In fact, many of us are conscious or unconscious adherents to the concept (popularized by Carl Sagan, but perhaps traceable to something called ‘Hume’s maxim’) that “Extraordinary claims require extraordinary evidence.” Or if not extraordinary evidence, at least some evidence. . . . right?

Not so in the pages of the latest issue of the Proceedings of the National Academy of Sciences (PNAS) in which Donald Williamson has recently published his notion that the larval stage of lepidopterans (known to most of us as the caterpillar), arose as a consequence of hybridization between insects and the Burgess Shale living fossil onychophorans (aka. velvet worms, see previous blog post). Although this hypothesis would be very interesting if found to be true, the author provides us with absolutely no evidence to support his claim (aside from observing the superficial similarity between adult velvet worms and larval moths and butterflies, which he illustrates in some very poorly reproduced line drawings that really need to be seen to be believed).

Discussed extensively by Jerry Coyne in his blog post entitled “Worst paper of the year?”, this article has already received more press attention (most of it, unfortunately, negative) than many of us will receive in our lifetimes. Of particular note was a lengthy article on the paper published in “Scientific American” which unflatteringly likens PNAS to the “National Enquirer,” although the analogy might be better suited to the “Weekly World News,” a more frequent purveyor of stories on strange hybrids (such as this gem on a purported goldfish–piranha cross). Much of both Coyne’s blog entry and Scientific American article focus on the very undemocratic review process in place at PNAS that is unique among high-tiered scientific journals in the U. S. At PNAS, candidate articles can be submitted to the journal directly and subject to normal scientific peer review (a process known as “direct submission”), or they can be “communicated” by a National Academy member. In the case of communicated submissions, the communicating member selects referees to review the submitted manuscript. For Williamson’s paper the communicating NAS member was Lynn Margulis, most famous for her revolutionary but now widely accepted theory for the endosymbiotic origin of mitochondria in eukaryotes. (As a point of irony with regard to the Sagan quote, above, Margulis is also a former wife of Carl Sagan.) Margulis admits in the “Scientific American” article that it took six or seven reviews to find the “‘2 or 3’ necessary to make a case for its publication” and is described as having a “fondness for weird theories.”

Scorn has been ladled on a review process that is designed this way (notably, here), but does it also have some merit if it allows the seasoned and respected scientists that mostly compose the National Academy a means of facilitating the publication of potentially revolutionary ideas that might otherwise never land in such a prestigious journal? The Williamson article seems to provide evidence that this merit comes at a cost, but then there’s no such thing as a free lunch is there?


Susan Perkins said...

I just love the notion of a butterfly "mistakenly mating with a velvet worm"...was the butterfly sipping the nectar of the bertam palm? (Note the citation of another PNAS article, albeit a direct submission.)

Matt Brandley said...

"Fortunately, this situation is changing, and soon PNAS manuscripts will receive the same rigorous review as regular journals offer"

Does anyone have more info on this? I.e., is this really going to happen?

It's always bothered me that there is a two-class system in PNAS.

Luke said...

@Matt Brandley

I don't know any more about that quote, but I think it raises a really interesting question: How often do members communicate papers that end up having a major impact on a field, but that wouldn't have otherwise gotten published in a top journal (or any journal!).

For example, can anyone think of any citation classics that were published in PNAS via this method of submission?

I think that communicated papers might potentially serve an important role in pushing radically new perspectives or "outside of the box" ideas that would inevitably get hung up in the review process (as Liam pointed out).

But this is testable! Perhaps it's time that someone takes a critical (and quantitative) look at just how beneficial this avenue really is. Is it worth the high cost?

fdelsuc said...

More information on the change in PNAS publication policy from the ScienceInsider.

Joe Felsenstein said...

Yes, it's true, Track I (a member sponsoring papers by someone else) is going away next year. It can't be too soon for me. One gets whined at by acquaintances to please get their papers in, and is tempted to accede to the first two such requests of the year, just to get it over with.

Now if we could only persuade European universities and institutes that publication in PNAS is not the only criterion for whether someone is worth appointing, we could reduce the number of papers coming in and have some of them go to other good journals.

People who send in papers to Track III (the ordinary review of papers by outside authors) should expect a highly random result. PNAS is under pressure to reject most papers, otherwise soon a single issue would be enormous. Papers are quickly screened without full review and many are rejected at that stage, often without anyone in that field even having seen them. So after you experience this, don't get mad, just send it somewhere else.

Frank Anderson said...

This is nothing new for Williamson, but PNAS...hoo boy. Williamson argued about twenty years or so ago that many marine invertebrate larvae (which often look quite different from the adult forms) are the results of hybridization events between echinoderms, bryozoans, etc. with long-extinct Cambrian (or earlier) species that...well, looked like the larvae. Incredibly, this butterfly/onychophoran idea is even fruitier than his earlier conjectures...

Dan Warren said...

There's an interesting new article on Higher Ed about this, called A Journal's Second Thoughts.

James MacAllister said...

The article above has perpetuated a myth that " Margulis admits in the “Scientific American” article that it took six or seven reviews to find the “‘2 or 3’ necessary to make a case for its publication” and is described as having a “fondness for weird theories.” The only quotes by Margulis in Scientific American are "6 or 7" and "2 or 3" the rest of the sentence is an invention of the reporter. One might ask why the reporter who obviously thought he heard something juicy a la National Enquirer did not bother to clarify what was being said. Controversy sells journals too. One of Williamson's main critics accuse him of publishing science fiction, but as Williamson points out, this critics "proof" has been shown to be science fiction by more competent molecular phylogenic technicians.