Gene Likens (Wikipedia link, naturally) is an ecologist who set up a longterm study of a forest in New Hampshire. That study found that the water entering the ecosystem was unusually acidic, a finding that was eventually tied back to pollution. This turned out to be one of the earliest indications of acid rain.

Likens might be expected to be satisfied with seeing his findings become widely accepted and eventually serve as the basis for national policy. But any satisfaction he felt almost certainly took a hit because he made a terrible mistake: he tried to make sure the Wikipedia entry on acid rain was accurate. In a new paper, Likens says "we noticed that some corrections we or others made on the acid rain article had been changed by major edits to introduce (or re-introduce) balderdash and factual errors into the content."

Looking more closely, Likens found that, even though the page typically had protected status, edits came fast and furious:

At 10:20am, an anonymous editor (identified only by an IP address), removed the introductory paragraph which defined acid rain and replaced it with a statement calling acid rain “a load of bullshit.” This change was quickly reverted, but the next day the paragraph was again deleted and replaced by “Acid rain is a popular term referring to the deposition of wet poo and cats.” Five minutes later this edit was reverted and repeated again, and then reverted again. The following day (December 2, 2011) another sentence was changed from “During the 1990s, research continued.” to “During the 1990s, research on elfs continued [emphasis added],” which remained for over seven hours. Later that day the sentence "AciD Rain [sic] killed bugs bunny” was briefly added. Fifteen minutes later the section title “Chemistry in cloud droplets” was changed to “Blowjobs.”

Undeterred, Likens got together with another faculty member (Adam Wilson) to look into whether acid rain was unusual in terms of scientific topics becoming an edit war zone. The two figured it was probably a result of the topic's role as a political controversy. So they decided to look at two other controversial topics: climate change and evolution. For controls, they chose heliocentrism, general relativity, continental drift, and the Standard Model of physics. They then downloaded the entire edit history between June of 2003 (when someone decided that heliocentrism merited its own entry) through July of 2012.

(All the data and the code used for analysis have been posted at Figshare.)

For the non-controversial topics, edits were typically made every few days, and they tended to be short, with a mean of less than 20 words changed per day. General Relativity had the highest peak edits per day, at 37; the rest were 25 or less.

Acid rain was ever so slightly worse. It averaged an edit every other day, with a mean of 36 words changed each day. Evolution was a bigger battle ground, but global warming was where the right fight took place. It saw 231 edits on a single day and had a mean of two edits every day throughout the entire period. A mean of 111 words were changed every day (second to evolution's 142 words).

Part of this may simply be prominence. There appears to be a rough correlation between the mean page views and some of these values, but with only five examples, it's hard to determine if it's significant. And this wouldn't necessarily contravene the authors' hypothesis, given that page views may be a product of social controversy.

Wilson and Likens note that some of this could easily have been averted. Software could easily have caught edits like "blow job" before they made it to the live version of the site. But some of the other edits simply introduced subtle errors (like reversing the meaning of a single sentence). For these cases, the authors can do little more than suggest the obvious: caution. "Two students could obtain, within seconds, diametrically different information on a controversial scientific topic," they write. "Educators should ensure that students understand the limitations and appropriate uses of Wikipedia, especially for controversial scientific issues."

PLoS ONE, 2015. DOI: 10.1371/journal.pone.0134454 (About DOIs).