Do hiccups serve any actual useful biological function?

Probably echoing what others have said, but here's an article with a salient section:

With all these disadvantages, and hardly any advantages to speak of, you might be wondering if hiccups serve a purpose at all. Well, some scientists have argued in the affirmative.

They point to the fact that even human fetuses hiccup, long before they’re born. In fact, the diaphragmatic spasms are more common in infants than in adults. It’s possible that this reflex helps prevent fetuses from breathing in amniotic fluid while still in the womb; likewise, it could prevent newborns from choking on milk while breastfeeding.

And still others have proposed that hiccuping in the womb trains a fetus’ respiratory muscles for all the breathing they will have to do after birth.

But humans aren’t the only animals that hiccup; pretty much any species that breathes exclusively air — including all mammals — can suffer the same fate. (Birds and reptiles, on the other hand, get a free pass.)

In fact, that’s the reasoning behind another theory, which posits that hiccups are merely an evolutionary “leftover” in mammals, dating all the way back to our fishy ancestors. When these species transitioned from gill-based breathing in the water to lung-based breathing on land, while still possessing both organs, a breathing system that allowed them to quickly close the glottis and direct water only to the gills was beneficial.

We see a similar process play out on a smaller scale when tadpoles grow up and transition into frog-hood. And that may not be a coincidence; believe it or not, the neural patterning that generates a hiccup in humans is almost identical to the neural patterning involved in respiration in amphibians.

I believe I read that it helps with lung development when the fetus is swimming in the water in the womb or something like that. But otherwise not really useful.

I read (this morning) that there's a theory that hiccups are a reflex to pump air across one's gills, and are more common in foetuses & premature babies as their lungs aren't fully developed...

So I guess if that is the case (as it's a theory) then yes, just not in humans - they're remnants of over 300 million years ago

There was an explanation for it in The Inner Fish book. I'm fuzzy about the details, it's been a while since I read this but essentially it is to prevent drowning when critters switch from gills to lungs like tadpoles.

A few things. First, the only tip I’ve even been given about getting rid of hiccups is drinking a glass of water upside down. As in, lips to the backside of the glass then leaning forward so far you can drink it. And you must drink quite a bit, maybe 300ml. Is this purely anecdotal? For me and those around me, yes, but maybe there is research about it. But it works for us, without fail, and it seems unbelievable even to me.

Regarding sneezing, I am currently discovering it has another feature where after having a few prosthetic discs inserted into your lower back via your abdomen, a sneeze also doubles as the world’s fastest impetus for suicidal ideation.

From what I understand: We don't know! Science hasnt actually figured it out yet and I haven't even read or heard about theories as to why we do it in regards to an evolutionary trait.

As for making them stop, there are several possible solutions:

• hold your breath
• gulp down some water
• smoke a cigarette
• Have the pants scared off you

The cure I've always used is to suck water through a restricted straw. I take a plastic straw, pinch it in the middle with a paperclip, and drink a small glass of water through it.

The science is still out on what causes hiccups, why we get them, and how exactly to stop them.

I read once that your body does it when your blood is low in oxygen, but I have no idea if that's true or not.

Hiccups, I was always told, are when the gases in something release out of it during digestion, like how a hollow carcass in the sea dissolves releases all its bubbles, which if correct, means it's less a biological function and more a biological response, one that can be avoided by not eating anything hollow or that which contains a mixed chemical content capable of varying forms of interaction, hence the hiccups you might get after drinking certain beverages.