Why Do We Hiccup?

The hiccup is perhaps the most useless thing your body does.

It arrives without warning, accomplishes nothing, and leaves on its own schedule. It is not a reflex with a function you can point to — not like sneezing (clearing airways), or coughing (expelling irritants), or vomiting (removing toxins). It does none of those things. A hiccup simply: happens.

It has been annoying humans since before recorded history. We have ancient remedies for it — holding your breath, drinking from the wrong side of a glass, being frightened, pressing on your eyeballs — and none of them work reliably, because nobody understands why hiccups start in the first place.

But one hypothesis, from an unexpected direction, suggests that the hiccup isn’t useless at all. We just finished needing it about 375 million years ago.

What Actually Happens

A hiccup is a two-part event.

First: an involuntary spasm of the diaphragm — the dome-shaped muscle beneath your lungs that drives breathing. The spasm causes a sudden, sharp intake of breath.

Second: about 35 milliseconds later, the vocal cords (glottis) snap shut. This produces the characteristic sound. The hic.

That 35-millisecond gap is precise. It’s not a side effect of the spasm — it’s a coordinated response. Something in your nervous system is actively closing your airway almost immediately after the spasm opens it.

The reflex arc runs through the vagus nerve and the phrenic nerve, both of which report to a small set of neurons in the brainstem. This brainstem circuit can be triggered by eating too fast, swallowing air, consuming carbonated drinks, temperature changes, emotional stress, or alcohol. It can also trigger for no apparent reason at all.

A hiccup episode typically lasts a few minutes. Occasionally longer. The record is held by Charles Osborne of Iowa, who began hiccupping in 1922 while slaughtering a hog and did not stop until 1990. Sixty-eight years. An estimated 430 million hiccups. He died a year after they stopped. His case was studied extensively, and no one could explain why they started, why they continued, or why they stopped.

The Theories

The most persistent explanation is that hiccups are a vestigial reflex — a leftover from an evolutionary chapter we’ve long since closed.

Neil Shubin, a paleontologist at the University of Chicago and author of Your Inner Fish, points out that the neural circuit responsible for hiccupping bears a striking resemblance to the breathing circuit found in tadpoles and fish that possess both lungs and gills. These animals need to pump water over their gills while preventing water from entering their lungs — a rhythmic pattern of closing the glottis after breathing that is structurally identical to the hiccup reflex.

Shubin argues that the hiccup circuit is a direct inheritance from an ancestor that lived before the transition from water to land — possibly a creature like Tiktaalik roseae, the 375-million-year-old transitional fossil he famously helped discover in the Canadian Arctic. That fish had fins that could prop it up and primitive lungs alongside gills. It needed a circuit that could sequence gill pumping and lung breathing. We still have that circuit. We just don’t have gills anymore.

This would explain why the hiccup reflex is so deeply wired — it’s in the brainstem, not in the cortex. You cannot consciously override it because it predates the neural architecture for conscious control.

The Competing Hypothesis

A second theory, proposed by Daniel Howes and colleagues, takes a more developmental angle: hiccups are practice for nursing.

In fetal development, hiccupping begins around the ninth week of gestation — well before any feeding is possible. Fetuses hiccup for extended periods in utero, apparently as a form of diaphragm exercise. The coordination required for suckling at a breast — rhythmic contraction of breathing muscles, precise timing of swallowing, airway management — might be learned through fetal hiccupping.

This would explain why hiccupping is most intense in infants (who hiccup after nearly every feeding) and decreases markedly as we age. The reflex serves a purpose early, then gradually fades to background noise in adult life.

Neither theory fully explains why the hiccup reflex persists with such apparent purposelessness in adults. Both could be true simultaneously — a reflex that had one ancient purpose and then found a second use before becoming a vestigial oddity.

The Folk Remedies (Why None of Them Work)

Thousands of hiccup cures have been documented across cultures and centuries. The common categories:

Breathing interventions — holding your breath, breathing into a paper bag. These raise CO2 levels in the blood, which can reduce diaphragm spasms by suppressing the brainstem’s respiratory drive. They work sometimes because they’re addressing a plausible mechanism. But they don’t consistently work because the trigger varies — if your hiccups are nervous-system irritation rather than CO2 imbalance, CO2 won’t fix them.

Swallowing interventions — drinking water upside down, swallowing sugar, gargling. These activate the swallowing reflex, which may compete with the hiccup reflex for use of the shared vagal pathways. Again: plausible, inconsistent.

Distraction/startle — being surprised, frightened, or intensely distracted. May work by briefly resetting the brainstem circuit. Unreliable.

The reason no cure is universal is that hiccups don’t have a single cause. The brainstem circuit can be activated by multiple pathways. A remedy that works by interrupting one pathway fails against another.

For hiccups lasting more than 48 hours (persistent hiccups) or more than a month (intractable hiccups), the cause is usually something that needs medical attention: esophageal irritation, central nervous system lesions, metabolic imbalances, or drug side effects. Charles Osborne is the extreme case; persistent hiccups are generally a symptom of something treatable.

The Strangeness

What stays with you about hiccups isn’t the mechanism — it’s what they reveal.

Your body contains machinery you didn’t choose, don’t understand, and can’t fully control. Some of it dates to before your species existed. Some of it served a purpose so long ago that the context is gone, and the reflex runs on anyway.

The hiccup is a message from your evolutionary past. It says: you were once something else, something that lived at the boundary of water and land and needed to keep both systems running at once. That chapter ended hundreds of millions of years ago. You carry the footnote in your brainstem.

Every time it fires, you’re briefly running ancient code.

The good news is that it usually stops on its own.

The less good news is that for Charles Osborne, it took 68 years.