It's Not Just Colons?

I've blogged at length about titular colonicity, most recently here.  The idea is simple: as an academic discipline "matures" you find more and more journal article titles with a colon.  Yeah, people study this stuff.  And now I've stumbled across a similar study, this one about question marks.  The article title? 

Scholarly communication in transition: The use of question marks in the titles of scientific articles in medicine, life sciences and physics 1966–2005

Which is odd, because the title has a colon, not a question mark.  I'm very confused.  As the abstract explains:

We examined nearly 20 million scientific articles and recorded the development of articles with a question mark at the end of their titles over the last 40 years. Our study was confined to the disciplines of physics, life sciences and medicine, where we found a significant increase from 50% to more than 200% in the number of articles with question-mark titles.

A couple of points.  First, I'd kill myself before I every conducted a content analysis of a bejillion articles in a search for question marks.  Second, I'd kill myself again, just to be sure I did it right.  And third -- this kinda matters.  Not me killing myself, though some might cheer the notion, but rather it's interesting how academic fields ripen and mature and seek out ways to make themselves seem more -- er -- academic. 
 
I should point out that one of the most popular terms people search for, and end up here, is titular colonicity.  The other popular one is cognitive mobilization.