At "the Festival of Bad Ad-Hoc Hypotheses, or BAHFest, a satirical conference on evolutionary biology held at the Massachusetts Institute of Technology."

One theory addressed "why we yawn... one of 'the enduring mysteries of human physiology,'" according to Emma Kowal, who offered this bogus theory:

Flying insects are high in protein. They gather in dense swarms most frequently at dawn and dusk, not-so-coincidentally the times of day when we are most likely to yawn.

Therefore, she says, “these insects served as an alternative protein source for our hunter-gatherer ancestors, with yawning as the primary gathering mechanism.” In other words: We evolved to yawn to catch bugs to eat.

Ms. Kowal, a senior studying chemical and physical biology, cited as evidence everything from our chemical response (“after we yawn, there’s a spike in cortisol levels, which is a mark of hunger”) to the way our faces distort (“eyes shut so insects won’t get in, mouth open as wide as possible to maximize capture”).

 (That link was sent by a reader who saw that I'd taken an interest in a particular yawn.)