Language shift

Language shift, also known as language transfer or language replacement or language assimilation, is the process whereby a speech community of a language shifts to speaking another language. Often, languages that are perceived to be higher status stabilise or spread at the expense of other languages that are perceived by their own speakers to be lower-status.

For prehistory, Forster et al. (2004) and Forster and Renfrew (2011) observe that there is a correlation of language shift with intrusive male Y chromosomes but not necessarily with intrusive female mtDNA. They conclude that technological innovation (the transition from hunting-gathering to agriculture, or from stone to metal tools) or military prowess (as in the abduction of British women by Vikings to Iceland) causes immigration of at least some males, who are perceived to be of higher status than local males. Then, in mixed-language marriages with these males, prehistoric women prefer to transmit the "higher-status" spouse's language to their children, yielding the language/Y-chromosome correlation seen today.

The process whereby a community of speakers of one language becomes bilingual in another language, and gradually shifts allegiance to the second language is called assimilation. When a linguistic community ceases to use their original language, language death is said to occur.

The rate of assimilation is the percentage of individuals with a given mother tongue who speak another language more often in the home. The data are used to measure the use of a given language in the lifetime of a person, or most often across generations within a linguistic community.

In the context of the Indo-European migrations, it has been noted that small groups can change a larger cultural area.Michael Witzel refers to Ehret’s model "which stresses the osmosis, or a "billiard ball," or Mallory’s Kulturkugel, effect of cultural transmission." According to Ehret, ethnicity and language can shift with relative ease in small societies, due to the cultural, economic and military choices made by the local population in question. The group bringing new traits may initially be small, contributing features that can be fewer in number than those of the already local culture. The emerging combined group may then initiate a recurrent, expansionist process of ethnic and language shift.

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