Last & Least

Genetics of language

Dr Binoy Barman

ALMOST all traits of human body as well as that of other animals are controlled by genes. Physical growth, structure, height, and colour of skin, appearance -- everything has their root in genetic matter. Even our language that we learn in childhood and use throughout our life is also connected to genetics. Particular genes determine the growth and structure of certain parts of brain, which have direct link with language learning, production and comprehension.

Genes are parts of the DNA (deoxyribonucleic acid) in a cell, which contains information in a special pattern. These are certain types of chemical compositions, which act as code, hence called 'genetic code'. The four basic components of genes are adenine, guanine, cytosine and thiamine. These are the building blocks of gene with 'double helix' architecture. These are like alphabets, which are combined in various ways to write instructions for animal development and behaviour. Genes are transferred from parents to offspring so that they share the same basic characteristics.

For centuries it has been debated how children learn language. Behaviourists have claimed that they learn language from environment imitating their parents. Opposing their views, the mentalists have claimed that children are born with some sort of innate the linguistic property, which enables them to learn a language. A third alternative view is expressed by cognitive psychologists. They claim that language grows in children through a process of 'maturation' as their brains and other organs develop, boosting up the cognitive faculty, which again facilitates language development. Behaviourists put utmost emphasis on experience and social interaction; mentalists emphasises the innate language faculty; and the cognitivists rely on the prime role of psychophysical maturation. The battle between the three parties still continues.

American linguist Noam Chomsky is a great advocate of innatism, embed in mentalist philosophy and psychology. He claims that babies are born with some fundamental knowledge of language, which he terms 'universal grammar'. It is the hidden core shared by all languages, accounting for the commonness of learning process observed in children across cultures. It is this grammar for which a child can easily learn any language in which he is put at birth. Grammars of particular languages, with particular sets of words and rules, are built upon the universal grammar, it is claimed.

Although Chomsky's universal grammar is a matter of great controversy, it has been acknowledged by all linguists that language has a physiological foundation and, more particularly, genetic foundation. Language has been found to have close link with particular brain locations. For example, the left hemisphere of brain has been found connected to most of the language functions. Broca's area, Wernicke's are and motor area of brain are linked with language production, comprehension and movement of vocal organs respectively. If any of these parts are damaged, the ability to use language is destroyed or impaired, the condition being called 'aphasia'. Damage to Broca's area results in Broca's aphasia and damage to Wernicke's area results in Wernicke's aphasia. The former affects the power to produce language and the latter the power to comprehend language. In case of damage to motor area, the power to move vocal organs is lost. Recent research has revealed that abnormality in 'basal ganglia' -- a region in the motor area of the brain -- is responsible for the difficulty in moving lips and tongue.

Human beings may face other types of linguistic diseases such as 'dyslexia' and 'grammar blindness'. In the first case, one cannot identify alphabets and so cannot learn to read and write. In the second case, one cannot learn the rules of grammar being unable to put words in correct order and form. The genetical scientists have found that particular genes are responsible for these two kinds of linguistic disorder. A gene called 'DFNA16' located in chromosome-2 has been claimed to cause dyslexia and another gene called 'FOXP2' located in chromosome-7 has been linked to grammar blindness.

Scientists claim that FOXP2 is required during early embryonic development for the formation of brain regions associated with speech and language. The defect in the gene causes devastating effects on brain development, resulting in speech disorder, more precisely, and grammar blindness.

'Williams Syndrome' and 'Autism' are also the results of linguistic disorder. In the first case, the power to use language shoots abnormally but analytical power slumps drastically. In the second case, the situation reverses -- a person's power to use language falls drastically but his analytical power increases abnormally. The patient of Williams Syndrome talks a lot though not intelligently. On the other hand, the patient of autism is shy of talking but he/she is very good at reasoning and mathematics. But, surely, both of them are abnormal. Scientists think that a gene called 'LIMK1' in the arm of chromosome 7 is responsible for William Syndrome. The gene responsible for autism has not yet been pinpointed but many think that a gene relating to the growth of limbic part of brain might cause this.

Now it is certain that the particular parts of brain that control language production, comprehension and movement of vocal organs are related to particular genes. As long as these genes work properly, Broca's area, Wernicke's area and motor area develop and function properly so as to perform special functions attributed to them. If the genes are damaged, the related areas are affected, hampering language performance. Therefore for our language capability, the health of brain and genes is essential.

It is curious to ask how and why the genes of language have been created in human cells. Evolutionary linguistics provides an answer. Language is characteristically a trait of Homo sapiens, which evolved about 1,00,000 years ago. They first started to use words from the existential need to warn others about the dangers around. As they were successful in doing so, the ability was codified in their genes. With the passage of time they were more skilled in using words. At first they used only separate words; but in course of time they learnt to connect words, creating syntax. Part of their linguistic capability flowed down genetically through progeny while part remained subject to social learning. Evolutionary pressure is the basis of linguistic genes.

How genes are related to human language is a relatively new area of research. It falls within the wide spectrum of biological science, precisely, genetics. Human genome research has opened up a new horizon of knowledge necessary for understanding ourselves -- all our characteristics including language. We are yet to know many things about the relationship between language and genes. But we can hope the unknown will be known with the earnest efforts of the scientists, who are poised to shape up a distinct discipline called 'linguistic genetics' or 'genetical linguistics'.

(The writer is Assistant Professor and Head, Department of English, Daffodil International University)