Apparently, humans have long looked into the back of their throats, or down others', at the bit of flesh that dangles and hangs there and wondered: What is that thingy for? A paper published in 1992 titled "The riddle of the uvula" references a history of "interesting and contradictory observations."
Science journalist Robbie Gonzalez recently rounded up some of the theories and unknowns surrounding the uvula at io9. He asked Katie Plattner, a speech-language pathologist for the L.A. Unified School District why we have them:
"I think one theory is to increase surface area where a gag reflex can be triggered so nothing too big gets down there without you knowing," she replied. She then added: "I also might have made that up, but [it] seems right."
When I asked Plattner if I could quote her, she said "If you include that I don't really know, sure!" Why would I quote her if she's not really sure? Because it turns out the theory she floats actually stands up. More importantly, though, her qualification of that theory captures a lot of the uncertainty that surrounds the uvula and its function.
The gag theory is supported by a review that pins the uvula down as one of five zones that triggers the gag reflex.
The uvula may be important for speech — it’s used to make uvular sounds (think of the trilled r’s in French), but it could also affect voice quality. At least one study notes that whatever it does isn't noticiable enough to prevent uvular removal from being routine. In northern Morocco, a physician observed that many people had their uvula snipped out, he reported in 1965. He wrote, "The absence of uvula was in all cases imputable to surgical removal during childhood, mostly soon after birth. The operation is performed on infants of both sexes; it is carried out either by the caretaker or sexton of the neighborhood mosque, or by a barber (mohallem hayyam). Many barbers in tradition-fast Morocco are still practical surgeons as they were in medieval Europe."
The "Riddle of the uvula" paper observed that the human uvula is larger and more complex in humans than in baboons. (It wasn’t even present in other mammals.) They argue that this supports the idea that the uvula is important for speech, a feature that distinguishes humans. The researchers also noted that uvula can produce a "large quantity of fluid salvia that can be excreted in a short time."
Maggie Ryan Sandford at Mental Floss also compiled a list of theories about the uvula and some problems:
- That it once helped guide the flow of food and water, and, in humans, was a mere remnant from previous mammals who had to lean down to eat and drink.
- That it contributed to “chronic cough.” A problem that 19th-century doctors treated with a “simple” “clipping” procedure.
- That it contributes to cardiovascular problems like sudden infant death syndrome (SIDS) and sleep apnea.
It could be that all the theories are true to some extent, but as of now the uvula remains a curious structure to ponder.