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?