Whether it is a joke among friends or an emotionally charged insult, people commonly utter curses in social situations. Every culture has its own group of taboo words that arise from biology and religion. It is clearly a part of human nature to set aside certain words as forbidden, but why is it also natural for humans to use them?
Scientific research is opening new frontiers in understanding this common but challenging human behavior. People with a unique symptom of Tourette's syndrome known as coprolalia, or the uncontrollable urge to utter curses and other socially inappropriate comments, are proving to be a valuable resource in this area of study.
Coprolalia afflicts five to 30 percent of people with Tourette's. It can be a deeply troubling and disruptive condition. An episode of coprolalia usually begins with a trigger. A word or two in a conversation could instigate a string of expletives. Often, however, coprolalia arises spontaneously and with no apparent cause.
Recent studies have used brain imaging to determine the anatomical basis of cursing in the brain. Tourette's patients with coprolalia are observed with either positron emission tomography (PET) or functional magnetic resonance imaging (fMRI), two techniques used by neuroscientists to examine the brain at work. Patterns of brain activation are correlated with the patient's verbal tics.
Functional imaging suggests that the primitive and advanced parts of our brains fight to override each other when we curse. Deep-brain structures, such as the thalamus and basal ganglia, are activated simultaneously with the more evolutionarily recent prefrontal cortex and language cortex.
The basal ganglia and thalamus are parts of the limbic system, a group of brain structures located deep below the cerebral cortex. The limbic system is associated with a variety of basic behaviors such as aggression and impulse, both of which are associated with cursing.
In contrast with the instinctive behaviors arising from the basal ganglia, the prefrontal cortex is responsible for what psychologists call executive functions, which include planning and inhibition of our impulses. In episodes of coprolalia, the prefrontal cortex attempts to override a behavior known to be socially inappropriate.
There are a variety of theories explaining why verbal tics in Tourette's syndrome frequently involve outbursts of cursing.
Scientists believe curse words are selected because of their short, sudden sounds. This theory is supported by the observation that curses in most languages have a similar phonetic pattern of one or two abrupt syllables.
Other scientists argue that curse words are chosen specifically, albeit unconsciously, for their offensive meaning. Even though coprolalia arises rapidly and may be difficult to control, individuals will often automatically tailor their curses for the specific situation.
A recent case report supports the theory that the words chosen in coprolalia are important for their meaning, not their phonetic structure. Physicians reported a deaf man with Tourette's who used sign language to spell out obscenities during fits of coprolalia. Since the man had been deaf since birth, he had no concept of the sound patterns of words. The scientists concluded that meanings motivated his outbursts.
Cases of coprolalia associated with Tourette's may be rare, but they can teach scientists a great deal about the neurological basis of cursing. Outbursts of cursing seem to be a fairly primitive behavior, hard-wired into our brains in the early days of the human species. There is some evidence that chimpanzees and other primates engage in similar behavior.
The reasons for this behavior are complex. Cursing is often an outlet for anger or frustration; many people report feeling better after cursing. It is also a means of gaining acceptance into a group; people tend to curse more frequently within a small group of friends, perhaps indicating their comfort level with the people around them.
At the same time, the higher portions of our brains try to override cursing. People recognize that curse words are taboo and often socially inappropriate, even among friends. As a result, there is a certain allure to cursing that adds to its unique treatment in language and culture.
Interestingly, there are a variety of medical and surgical treatments that can alleviate coprolalia, at least partially. Surgically disabling nuclei in the thalamus and two related structures, the globus pallidus and the cingulate cortex, can lessen the severity and frequency of outbursts. Electrically manipulating the thalamus through deep brain stimulation may also be possible.
These findings raise interesting questions about the basis of cursing. How do certain words become taboo? What is the social benefit of maintaining such a group of words? How do people learn what these words are and internalize them to such a great idea? Further research will undoubtedly focus on these questions.
