Multilingualism has likely been common throughout much of human history. In tribal hunter-gatherer societies, multilingualism was common, as tribes need to communicate with neighboring peoples. In present-day areas such as Sub-Saharan Africa, where there is much variation in language over short distances, it is usual for anyone who has dealings outside their own town or village to know two or more languages.
When speakers of different languages interact closely, it is typical for their languages to influence each other. Languages normally develop by gradually accumulating dialectal differences until two dialects cease to be mutually intelligible, somewhat analogous to the species barrier in biology. Language contact can occur at language borders, between adstratum languages, or as the result of migration, with an intrusive language acting as either a superstratum or a substratum.
The result of the contact of two languages can be the replacement of one by the other. This is most common when one language has a higher social position. This sometimes leads to language endangerment or extinction.
Language contact can also lead to the development of new languages when people without a common language interact closely, developing a pidgin, which may eventually become a full-fledged creole language through the process of creolization. A prime example of this is Saramaccan, spoken in Suriname, which has vocabulary mainly from Portuguese, English and Dutch, but phonology and even tones which are closer to African languages.
A much rarer but still observed process is the formation of mixed languages. Whereas creoles are formed by communities lacking a common language, mixed languages are formed by communities fluent in both languages. They tend to inherit much more of the complexity (grammatical, phonological, etc.) of their parent languages, whereas creoles begin as simple languages and then develop in complexity more independently. It is sometimes explained as bilingual communities that no longer identify with the cultures of either of the languages they speak, and seek to develop their own language as an expression of their own cultural uniqueness.
Change as a result of contact is often one-sided. Chinese, for instance, has had a profound effect on the development of Japanese, but the Chinese language remains relatively free of Japanese influence, other than some modern terms that were reborrowed after having been coined in Japan. In India, Hindi and other native languages have been influenced by English up to the extent that loan words from English are part of day to day vocabulary. In some cases, language contact may lead to mutual exchange, although this exchange may be confined to a particular geographic region. For example, in Switzerland, the local French has been influenced by German, and vice-versa. In Scotland, the Scots language has been heavily influenced by English, and many Scots terms have been adopted into the regional English dialect.
Obviously, a language's influence widens as its speakers grow in power. Chinese, Greek, Latin, French, Spanish, Arabic, Persian, Sanskrit, Russian, and English have each seen periods of widespread importance, and have had varying degrees of influence on the native languages spoken in the areas in which they have held sway.
Some forms of language contact affect only a particular segment of a speech community. Consequently, change may be manifested only in particular dialects, jargons, or registers. The South African dialect of English has been significantly affected by Afrikaans, in terms of lexis and pronunciation, but English as a whole has remained almost totally unaffected by Afrikaans. In some cases, a language develops an acrolect which contains elements of a more prestigious language. For example, in England during a large part of the Medieval period, upper-class speech was dramatically influenced by French, to the point that it often resembled a French dialect. The same situation existed in Tsarist Russia, where the native Russian language was widedly disparaged as barbaric and uncultured.
Language Contact and Confidence in Second Language Listening Comprehension: A Pilot Study of Advanced1 Learners of German
Jul 01, 2006; Abstract: Over the past several decades, listening comprehension has not received a great deal of focus in foreign/second...