Biology 202, Spring 2005
Second Web Papers
On Serendip

The evolution of language has been a subject of debate for many years, but most participants in the discussion can generally agree that the brain as the central location for the formation of language. Three areas in the left hemisphere of the brain participate in the complex activities that comprise language generation and understanding. Wernicke's area is associated with spoken language comprehension, while Broca's area is tied to language production. These two regions are linked by Geschwind's territory which has recently been found to play an important role in the acquisition of language during childhood. Somewhere between the fifth and seventh years of life this area matures, culminating in the development reading and writing skills (3), (4).

The development of language is believed to begin very early in our lives. At birth, we are all endowed with more neurons then we will ever need in our lifetime. As
we age, these neurons undergo a process of connecting and pruning in relation to that which we encounter in our environment via a process often referred to as "neural
Darwinism" (7). Only those synaptic connections that are regularly stimulated and used will remain active while those that are unused will deteriorate. It is for this reason that many believe in the critical period hypothesis of language learning. The critical period hypothesis suggests that the ability to learn a language is restricted to the years before puberty. If language acquisition is attempted after this period has passed, considerable difficulty is encountered due to neurological changes in the brain (2).

For example, there are case studies of children who were neglected or abandoned during the early years of their lives and robbed of the essential human interaction that is critical for the formation of those areas of the brain related to language. One such example is the "savage" or "Wild Boy of Aveyron". The young boy was captured in the winter of 1800 in a small village in the south of France. Estimated to be around 11-12 years old, the boy appeared mysteriously from the woods and was captured by a villager. Devoid of clothing, speech or manners, it was estimated that the boy had been abandoned and spent five or six years surviving alone in the forest. His style of self expression was limited to using facial expressions and a few gestures, skills that were well below what one would expect of a child of his age. In this boy's case, even if he had gained some language ability prior to being abandoned, the isolation that he experienced may have contributed to a process of atrophy of neural connections in his brain. Even with continued effort to bring about the ability to speak and write, the boy failed to ever truly gain a fully functional ability to communicate broad ranging and sophisticated ideas verbally or in writing (6).

In the event that primary language acquisition proceeds normally, second language acquisition may be achieved; however studies suggest that the optimal period
for learning a second language falls within the range of the critical period. A second language may be learned with some difficulty later in life depending on the method of instruction, the similarity between the first and second language, and the individual's general aptitude for learning (8).

After language has been acquired and mastered, there exists the possibility for loss of language skills due to a condition known as aphasia. Aphasia can affect anyone at any age, but most cases are found among the elderly and are typically associated with a stroke. Other possible causes include tumors within or physical injury to the brain with loss of function typically corresponding with damage to one or more of the brain's language regions. Symptoms of this disorder can be mild to severe resulting in the loss of memory of a few words to the inability to construct or comprehend complex sentences. Global aphasia spans all language centers of the brain and affects the entire range of communication skills, while Broca's aphasia affects the frontal lobe and reduces speech output, as the centers for vocabulary retrieval and fluency are affected. Persons with Broca's aphasia retain the ability to understand spoken and written language but tend to drop small words such as "the", "it" and "and" from their communications thus producing sentences with vague meaning. A decline in language understanding occurs in the temporal lobe as Wernicke's aphasia diminishes the comprehension of written and spoken words. These individuals often construct meaningless sentences by making up
words and/or putting words in the wrong order. Currently there is no cure for aphasia; however depending on the level of brain damage, speech therapy may be an effective treatment. In some cases language skills may only be lost for a few hours or days, as in the case of people who suffer very a very mild stroke (1), (5).

It is apparent that nature and nurture both play critical roles in language acquisition and retention. The development of language centers in the brain relies heavily on external stimuli while the retention of language depends on the continuous integrity of brain structure. It is through the study of exceptions to the norm that we may gain a firmer understanding of where and how language forms in our minds.

References

1)Aphasia Fact Sheet, National Aphasia Association website

2) The Impact of Abuse and Neglect on Neurological Development , Feral Children website

3) Brain imaging reveals new language circuits , Medical News Today website

4) Finding Geschwind's Territory , Mind Hacks website

5) Aphasia , National Institute on Deafness and Other Communication Disorders website

6) Shattuk, Roger. The Forbidden Experiment. New York: Farrar Straus Giruox, 1980.

7) Shreeve, James. "Beyond the Brain" National Geographic 2005: 2-31

8) A Critical Period for Second Language Acquisition?, Stanford University website


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