Language is a cognitive skill that seems to be unique to humans. There have been multiple debates on whether language has a genetic component to it and whether we are conditioned by the environment to acquire language. In linguistics (the scientific study of language), Noam Chomsky, a well-known linguist, is in favour of the hypothesis of a genetic predisposition. Chomsky proposed the idea that humans have an innate mental faculty that stores knowledge of Universal Grammar in the human brain. This faculty is also known as the Language Acquisition Device (LAD). Universal Grammar refers to the notion that humans are born with a knowledge of grammar that can be applied to any language in the world. Interestingly enough, there is evidence that supports Chomskys stance. It has been found that the stages and duration of language acquisition is universal.
Additionally, there is the evidence that there needs to be some input of the environment to activate this LAD. The amount of input, however, does not correlate with the language output produced by children, this is known as the poverty of the stimulus argument. This argument hypothesises that the input children receive when learning their first language is often incomplete or incorrect but is still enough to enable children to learn their native language correctly and completely. Chomsky hypothesised that this is a phenomenon that suggests that we are born with an internal knowledge of how languages are structured.
Further evidence for the genetic predisposition for language can be presented by the critical period, the time frame in which a child is able to learn their native language with ease and needs to learn to be able to speak it at all. This is evidenced by a case study involving feral child called Genie. Genie was abandoned at a young age and was never exposed to language before she was found. When she was found at age 13, she could not speak. After extensive language training it became evident that she would never be able to produce speech in the way we know it.
All those pieces of evidence suggest that we are indeed born with the ability to learn a language. But have researchers actually found a genetic component to aid the acquisition of speech and language? Until 2001, researchers were not sure what role genes were playing in the development of language. The gene that was found to be associated with language is called FOXP2 but it has several other functions that are not related to language. FOXP2 can be found on chromosome 7 and is responsible for switching genes on and off by producing a protein called a transcription factor which affects the expression of several other genes. It is also responsible for brain development and consequently affecting the development of language and speech.
FOXP2 has been found through analysing the DNA structure of KE families. KE families are British born families with a Pakistani origin. About half of the members of one family have a language and speech disorder called developmental verbal dyspraxia. Affected KE family members are unable to coordinate tongue and lip movements necessary to produce coherent speech. They also have a hard time stringing words together. It has been found that the mutation of the FOXP2 gene of affected KE family members comes down to the substitution of one amino acid which deactivates the FOXP2 protein. FOXP2 deactivation results in the inability control the expression of other genes. It is not clear whether the genes that it normally regulates are involved in speech and language directly. Researchers are working hard to find this out.
[Image: “Protein FOXP2 PDB 2a07” by Emw – Own work. Licensed under CC BY-SA 3.0 via Commons – https://commons.wikimedia.org/wiki/File:Protein_FOXP2_PDB_2a07.png#/media/File:Protein_FOXP2_PDB_2a07.png]