The case of a boy with a low IQ who became proficient in multiple foreign languages and studies of people with aphasia confirm that human language ability exists independently of other cognitive abilities and is determined by specific areas of the brain. This shows that language is a distinct function of the brain.
A 13-year-old boy with an IQ of less than 70 cannot button his own clothes or cut his own nails, yet he speaks more than 20 foreign languages, including French, Italian, Spanish, Greek, and Turkish, and can easily translate texts written in these languages into his native English. This extraordinary case provides important clues to help us better understand the relationship between the human brain and language ability. In particular, it confirms Chomsky’s hypothesis that human language ability is a distinct ability that is not related to other cognitive abilities.
The two types of aphasia reported in the literature so far suggest that there is a unique region in the human left brain that is responsible for language. Moreover, these studies further emphasize the independence of language skills. Given that the processing of language is complex and multilayered, the existence of such isolated abilities raises interesting questions about our brain structure and function. For example, it raises the question of why some people excel in certain areas, especially language, despite having low overall intelligence.
Some people with aphasia appear to speak very fluently at first glance because their intonation and pronunciation are normal, but on closer inspection, they use incorrect vocabulary and often meaningless words, known as Wernicke’s aphasia. Another characteristic of these patients is that they speak in relatively grammatically correct sentences, but unusually, they have difficulty remembering nouns. This type of patient was first reported in an 1874 paper by Carl Wernicke, who identified them as having damage to the back of the left hemisphere (Wernicke’s area). People with Wernicke’s aphasia are characterized by euphemizing simple, everyday nouns. For example, they might say “drink” instead of “water” or “where you smell” instead of “nose”.
In fact, when a person with Wernicke’s aphasia was shown a picture of a fish and asked to say what it was, he responded with the following statement
“I know what it is, but I can’t tell you. It’s in the water, it’s fun to catch it, on vacation. It’s not an animal, but it’s close to an animal. It’s good to eat. It’s a crab, no, no, it’s more like a crab, but it’s a fish, yes, a fish! That’s it.”
Some people with aphasia are the exact opposite of Wernicke’s aphasics. They use words according to their meaning but are grammatically incorrect. This type of aphasia, known as Broca’s aphasia, is characterized by stuttering, lack of functional vocabulary, such as investigative words, use only simple key words, and have difficulty choosing the right words. First reported to the scientific community by Paul Broca in 1861, autopsies of the brains of these patients revealed damage to the front part of the left hemisphere (Broca’s area).
Thus, aphasia research suggests that language skills are localized to specific parts of the brain, and that damage to these skills can occur independently of other aspects of cognitive ability. This shows that language exists as a distinct function of the brain, not just a representation of thoughts.
Currently, we know that damage to either side of the brain can restore some function to the neurons that connect the left and right hemispheres. Of course, if those neurons are damaged, the possibility of recovery is lost. And it turns out that different parts of the brain are responsible for different aspects of language, such as nouns and verbs, vocabulary formation, and sentence generation. So a patient with damage to the part of the brain responsible for sentences will have difficulty forming sentences, and a patient with damage to the part responsible for verbs will be unable to speak verbs.
These findings reveal the nature of language and the wonders of human cognition. Although language skills are rooted in specific areas of the brain, how they are expressed and how they develop is still complex and mysterious. Understanding how unique and complex the human brain is, and how language is an independent ability within it, will take many years of research.
