Should academic papers necessarily carry a sober tone? I was reading this paper titled "Optimal Symmetric Rendezvous Search on Three Locations." While talking about the history of search problems, the author mentions the following anecdote in passing.


  In 2007 a letter writer to the Guardian newspaper queried, “I lost my wife in the crowd at Glastonbury (a music festival). What is the best strategy for finding her?” A reader replied, “Start talking to an attractive woman. Your wife
  will reappear almost immediately.”


While I found it quite amusing to read this, I do not often come across papers with such witticisms. Is there an unwritten rule about the tone of sobriety that is considered appropriate in academic papers? Are jokes or anecdotes fine as long as they do not appear forced?
Are jokes or anecdotes fine as long as they do not appear forced?


To me, there is a single measure for this: does a sentence X contribute to the paper, or not. If the answer is no, it shouldn't be there at all. 

To apply the principle to the joke: if the joke illustrates a common problem which needs a solution, or illustrates a common (perhaps insufficient) solution to a well stated problem, then it certainly has a place in a research paper.

I understand scientific writing as a form of literature. I do not see any reason for literature (including scientific discourse) not to be entertaining as well, when appropriate. But everything has its time and place. However, it shouldn't be forced and has to fit the main contribution of the paper, hence the filter rule above.