In the early 1970s, the linguist David McAlpin produced a detailed proposal of a genetic relationship between Dravidian and the extinct Elamite language of ancient Elam (present-day southwestern Iran). The Elamo-Dravidian hypothesis was supported in the late 1980s by the archaeologist Colin Renfrew and the geneticist Luigi Luca Cavalli-Sforza, who suggested that Proto-Dravidian was brought to India by farmers from the Iranian part of the Fertile Crescent. (In his 2000 book, Cavalli-Sforza suggested western India, northern India and northern Iran as alternative starting points.) However, linguists have found McAlpin's cognates unconvincing and criticized his proposed phonological rules as "ad hoc". Elamite is generally believed by scholars to be a language isolate, and the theory has had no effect on studies of the language. In 2012, Southworth suggested a "Zagrosian family" of West Asian origin including Elamite, Brahui and Dravidian as its three branches.