Hiccups are triggered by electric signals
generated in the brain stem. Amphibian brain stems emit similar
signals, which control the regular motion of their gills. Our brain
stems, inherited from amphibian ancestors, still spurt out odd signals
producing hiccups that are, according to Shubin, essentially the same
phenomenon as gill breathing.
This is atavism, or evolutionary throwback activity, at work. Luckily, you do eventually stop trying to breathe through your gills when it dawns on your brain that you are actually a modern human, not a prehistoric fish.
So perhaps the next time you are hit with a serious bout of the hiccups, instead of drinking a shot of vinegar, concentrate on your humanity. Just read some Descartes, or Harold Bloom's Shakespeare opus, The Invention of the Human, and you'll be breathing like a person in no time.