Yoruba (/ˈjɒrʊbə/;[2] Yor. Èdè Yorùbá; Ajami: عِدعِ يوْرُبا) is a language spoken in West Africa, most prominently Southwestern Nigeria. It is spoken by the ethnic Yoruba people. The number of Yoruba speakers is stated as roughly 50 million, plus about 2 million second-language speakers.[1] As a pluricentric language, it is primarily spoken in a dialectal area spanning Nigeria and Benin with smaller migrated communities in Cote d'Ivoire, Sierra Leone and The Gambia.
Yoruba vocabulary is also used in the Afro-Brazilian religion known as Candomblé, in the Caribbean religion of Santería in the form of the liturgical Lucumí language and various Afro-American religions of North America. Practitioners of these religions in the Americas no longer speak or understand the Yorùbá language, rather they use remnants of Yorùbá language for singing songs that for them are shrouded in mystery. Usage of a lexicon of Yorùbá words and short phrases during ritual is also common, but they have gone through changes due to the fact that Yorùbá is no longer a vernacular for them and fluency is not required.[3][4][5][6]
As the principal Yoruboid language, Yoruba is most closely related to the languages Itsekiri (spoken in the Niger Delta) and Igala (spoken in central Nigeria).[7]
Yoruba is classified among the Edekiri languages, which together with Itsekiri and the isolate Igala form the Yoruboid group of languages within the Volta–Niger branch of the Niger–Congo family. The linguistic unity of the Niger–Congo family dates to deep prehistory, estimates ranging around 11000 years ago (the end of the Upper Paleolithic).[8] In present-day Nigeria, it is estimated that there are over 50 million Yoruba primary and secondary language speakers as well as several other millions of speakers outside Nigeria, making it the most widely spoken African language outside of the continent.
The Yoruba group is assumed to have developed out of undifferentiated Volta–Niger populations by the 1st millennium BC. Settlements of early Yoruba speakers are assumed to correspond to those found in the wider Niger area from about the 4th century BC, especially at Ife. The North-West Yoruba dialects show more linguistic innovation than the Southeast and Central dialects. This, combined with the fact that the latter areas generally have older settlements, suggests a later date for migration into Northwestern Yorubaland.[9] According to the Kay Williamson Scale, the following is the degree of relationship between Itsekiri and other Yoruboid dialects, using a compiled word list of the most common words. A similarity of 100% would mean a total overlap of two dialects, while similarity of 0 would mean two speech areas that have absolutely no relationship.[citation needed]
The result of the wordlist analysis shows that Itsekiri bears the strongest similarity to the South-East Yoruba dialects and most especially Ilaje and Ikale, at 80.4% and 82.3% similarity. According to the language assessment criteria of the International Language Assessment Conference (1992), only when a wordlist analysis shows a lexical similarity of below 70% are two speech forms considered to be different languages. An overlap of 70% and above indicates that both speech forms are the same language, although dialect intelligibility tests would need to be carried out to determine how well speakers of one dialect can understand the other speech form. Thus while the analysis shows that Igala, with an overlap of 60% is a completely different language, all other Yoruboid speech forms are merely dialects of the same Language.[citation needed]