People tend to be surprised when they learn that there is a lot of variation in the vocal tract (all those parts of your head and neck that you use to produce speech sounds). For example, the epiglottis, that little flap that keeps you from swallowing your food into your lungs, has between five and six completely different shapes. It can be thin and flat, with serrated edges, thick with rounded edges, or a mixture of the two. If looking at it didn’t involve sticking cameras down the throat via the mouth or nose, it would actually be pretty useful for biometrics.
The tongue doesn’t have quite as much variation in shape as the epiglottis, but there is one bit of variation that seems to get quite a bit of interest: tongue length.
So what can affect tongue length? Well, the biggest factor is probably how you measure it. The Guinness Book of World Records, for example, measures the length of the tongue from the tip of the extended tongue to the middle of the top lip. (The current record holder, Nick Stoeberl, can extended his tongue almost four inches past his top lip.) But, as you’ll notice looking at the diagram above, the amount of the tongue that can stick out past your lips is actually pretty limited. The tongue itself goes all the way down to the hyoid bone, in your throat. So if you want to accurately measure the entire tongue, probably the most accurate way is to measure from the tongue tip to the epiglottis (down in the throat) while the tongue is at rest. The downside to this, of course, is that it will trigger gagging and it’s hard to see what you’re doing at the back of someone’s throat. Plus it has the definite potential to block the airways. As a result, tongue measurement of this type tend to be done on cadavers. There are also some imaging techniques like x-ray, ultrasound or MRI. But let’s assume that you don’t have a couple hundreds of thousands of dollars’ worth of equipment or a medical cadaver just lying around and just focus on that first measurement–although be warned that it doesn’t have very strong inter-rater reliability.
Now that that’s out of the way, we can get down to business: what affects how far you can stick your tongue out? There are actually a lot of factors at work here:
- Frenulum: The lingual frenulum, that is. This is the little bit of tissue that connects the bottom of your tongue to the floor of you mouth. For most people this actually won’t affect tongue extension, but for some people it’s a big problem. Have you ever heard the expression “tongue tied”? This actually refers to a lingual frenulum that’s too short and extends too far towards the tip of the tongue. This condition, which is called ankyloglossia, is especially problematic when trying to produce speech sounds or for babies who are trying to nurse. In some cases, doctors may actually cut the lingual frenulum in order to free the tongue. For most people, though, cutting the frenulum would not increase freedom of movement or length of extension in the tongue. Plus, the risks associated with oral surgery are substantial.
- Bone structure and tooth placement: Bone structure and tooth placement can also affect how far the tongue can be extended. People with short face syndrome–yes, that’s a real medical diagnosis–and overjet tend to have smaller tongues. Other factors such as incisor position and whether a line drawn between the upper and lower sets of teeth tilts or not also co-vary with tongue length.
- Age: One obvious factor that affects tongue size is age. Adults’ tongues are approximately twice the size of infants’. This is surprising, given that the infant’s skull makes up 1/4 of its height where as for adults that figure is only 1/7. As a result, an adult skull is only roughly 1.75 times as large as an infant skull.
- Biological sex. Finally, there is a slight affect of biological sex. During puberty, high levels of testosterone and human growth hormone trigger growth, especially in the jaw and chin, and this effect is more pronounced in individuals with testes. As a result, their tongues tend to be longer. Too much human growth hormone–acromegaly–can cause growth to continue well past the point of comfort. It also causes the tongue to enlarge and shift forwards in the mouth.
You may notice all these factors have one thing in common: they’re not something you can change. Like your height or body-shape, tongue length isn’t really something you can really change about yourself. The good news, though, is that you can produce speech perfectly well with pretty much any length of tongue.