the Gilaks reside in the northern parts of the province, in Alamut. Apart from four Turkish-speaking villages higher up, the inhabitants of Alamut speak Gilaki and those of Rudbar Tati. Language The Gilaki language is a member of the Northwestern branch of the Iranian languages. It is the main language spoken amongst the Gilak people, although various regional and local dialects of the Gilaki language are common. Gilak people are fluent in both the Gilaki language and standard Persian. Persian is the official language of education in Iran, and since teachers are discouraged from using regional dialects and accents in class, the Gilaki language is taught to children at home. The Gilaki and Mazandarani languages (but not other Iranian languages) share certain typological features with Caucasian languages. However, with the growth of education and press, the differentiation between Gilaki language and other Iranian languages is likely to disappear. Gilaki is closely related to Mazandarani and the two languages have similar vocabularies. These two languages retain more than Persian does of the noun declension system that was characteristic of older Iranian languages. Genetics The Gilaks and their closely related Mazandarani occupy the South Caspian region of Iran and speak languages belonging to the North-Western branch of Iranian languages. It has been suggested that their ancestors came from the Caucasus region, perhaps displacing an earlier group in the South Caspian. Linguistic evidence supports this scenario, in that the Gilaki and Mazandarani languages (but not other Iranian languages) share certain typological features with Caucasian languages. There have been patterns analyzed of mtDNA and Y chromosome variation in the Gilaki and Mazandarani. Based on mtDNA HV1 sequences, the Gilaks and Mazandarani most closely resemble their geographic and linguistic neighbors, namely other Iranian groups. However, their Y chromosome types most closely resemble those found in groups from the South Caucasus. A scenario that explains these differences is a south Caucasian origin for the ancestors of the Gilaki and Mazandarani, followed by introgression of women (but not men) from local Iranian groups, possibly because of patrilocality. Given that both mtDNA and language are maternally transmitted, the incorporation of local Iranian women would have resulted in the concomitant replacement of the ancestral Caucasian language and mtDNA types of the Gilaki and Mazandarani with their current Iranian language and mtDNA types. Concomitant replacement of language and mtDNA may be a more general phenomenon than previously recognized. The Mazandarani