memory capacity, which would aid in the storage and retrieval of knowledge of a language. In 1991, for example, Neil Smith and Ianthi-Maria Tsimpli described Christopher, a man with non-verbal IQ scores between 40 and 70, who learned sixteen languages. Christopher was born in 1962 and approximately six months after his birth was diagnosed with brain damage. Despite being institutionalized because he was unable to take care of himself, Christopher had a verbal IQ of 89, was able to speak English with no impairment, and could learn subsequent languages with apparent ease. This facility with language and communication is considered unusual among savants. Neuroscience In communities Widespread multilingualism is one form of language contact. Multilingualism was common in the past: in early times, when most people were members of small language communities, it was necessary to know two or more languages for trade or any other dealings outside one's town or village, and this holds good today in places of high linguistic diversity such as Sub-Saharan Africa and India. Linguist Ekkehard Wolff estimates that 50% of the population of Africa is multilingual. In multilingual societies, not all speakers need to be multilingual. Some states can have multilingual policies and recognize several official languages, such as Canada (English and French). In some states, particular languages may be associated with particular regions in the state (e.g., Canada) or with particular ethnicities (e.g., Malaysia and Singapore). When all speakers are multilingual, linguists classify the community according to the functional distribution of the languages involved: Diglossia: if there is a structural-functional distribution of the languages involved, the society is termed 'diglossic'. Typical diglossic areas are those areas in Europe where a regional language is used in informal, usually oral, contexts, while the state language is used in more formal situations. Frisia (with Frisian and German or Dutch) and Lusatia (with Sorbian and German) are well-known examples. Some writers limit diglossia to situations where the languages are closely related and could be considered dialects of each other. This can also be observed in Scotland where, in formal situations, English is used. However, in informal situations in many areas, Scots is the preferred language of choice. A similar phenomenon is also observed in Arabic-speaking regions. The effects of diglossia could be seen in the difference between written Arabic (Modern Standard Arabic) and colloquial Arabic. However, as time goes, the Arabic language somewhere between the two has