Hiccups are an interesting phenomenon which everybody experiences at some point in their lives and there are many theories around why they happen. The first thing to understand is what they are. There are two different muscles involved in breathing, the diaphragm – a muscle below the lungs – and the intercostal muscles – muscles attaching the lungs to the ribs. Hiccups happen when these muscles become out of sync, causing the diaphragm to contact violently.
So we know what they are, but the question is why do they happen? And what is their purpose? The short answer is, we don’t know. Though there are many interesting theories.
IT has been noticed that although there is no obvious trigger, they are more likely to happen when a person has eaten or drunk something quickly, particularly fizzy drinks. Though hiccups obviously don’t always occur every time after you drink fizzy drinks. Other noted triggers are drinking alcohol and smoking, but these are rare occurrences when compared with the number of cigarettes an individual smokes a day or how often an individual will drink alcohol.
Clearly there is something else going on here, as another fact is that hiccupping is more common in babies, than adults. Did you know, that hiccupping has also been witness happening in foetus’ in the womb, suggesting that it could have an evolutionary mechanism.
From an evolutionary standpoint, in 1997 it was suggested that hiccupping had developed to prepare the respiratory muscles of the foetus for breathing after birth and also for clearing the lungs when fluid moved into them and shouldn’t be there. Which also could suggest that it helps suckling infants by preventing milk from accidently getting in to their lungs (see next paragraph). This is not, on the surface, a satisfactory explanation as a hiccup is more likely to cause a baby to ‘suck’ things/ fluids into the lungs rather than expel them.
One theory is that hiccups help with suckling in infants, preventing milk from getting into the lungs. This is a theory that comes from a theory about why hiccups may have existed in the evolution of humans in the first place. A mechanism very similar to hiccups is seen in many amphibians, forcing water away from the lungs and over the gills. This is a strong possible theory, particularly given that hiccups are seen in other mammals besides humans, but begs the question of why has it prevailed so long in evolution of fully terrestrial animals? An interesting theory on this is due to breast feeding, helping babies to learn to suckle without getting milk into their lungs. Though the process of hiccupping and suckling have similar mechanisms. This would also help explain why infants hiccup more than adults, but there are many muscles involved in suckling which are not involved with hiccupping, which leads to this being as highly flawed theory.
With all this in mind, many people have different ideas of ‘cures’ for hiccups. The simple truth is that none of these have been proven to work, but they are interesting non-the less. There are some common cures that are well known and some less common ones. The common ones appear to be: holding your breath, being scared, and drinking water upside down. Some others that I am aware of are putting salt under your tongue, swallowing whilst holding your breath (harder than it sounds), gargling with ice water, putting a cold key down your back (what?!), reflexology and breathing into a paper bag. If you Google ‘hiccup cures’ the list is never ending!
Breathing into a paper bag is the only one of these cures that appears to have some sort of biological basis, as it could be argued that it is linked to the evolutionary theory linking us to amphibians. The amount amphibians breath using their gills decreases with an increased amount of carbon dioxide (CO2) and because of this it is thought that breathing in more CO2 will reduce hiccups. Breathing in and out of a paper bag causes you to breath in air you have just breathed in, which have a much higher concentration of CO2 than the air we normally breath in.
Another suggested theory is that the first hiccup is the only one that is real and the rest area phycological. This is a weird suggestion, let me explain. The suggested reason for this is due to the first hiccup being a response to the body reacting to thinking it is drowning (which does seem to makes sense that this would happen if we eat or drink too fast), and the rest of the hiccups are the body continuing to respond to the initial stimulus. This can be some what supported by the fact that no cure has been shown to work, but people swear that they do. It’s a placebo effect, if you believe something will cure you then it will, particularly of hiccups are all in your head to begin with. The issue with this is that there is no scientific basis for it and this still doesn’t explain why they would happen in the first place!
The take home message from all this is that we simply don’t know what causes hiccups, but as they are not life threatening, then it seems okay that this is the case for now.
Iflscience is a very good reference for a lot of things:
This website has a lot of information, though is very technical:
Some interesting theories on here as well, though much less information: