by most linguists on the basis of the linguistic data. Most scholars place the homeland of Afroasiatic near the center of its current distribution, "in the southeastern Sahara or adjacent Horn of Africa." The African languages of Afroasiatic are not more closely related to each other than they are to Semitic, as one would expect if only Semitic had remained in an Asian AA homeland while all other branches had spread from there. Likewise, all Semitic languages are fairly similar to each other, whereas the African branches of Afroasiatic are very diverse; this suggests the rapid spread of Semitic out of Africa. Proponents of an African origin of Afroasiatic assume the proto-language to have been spoken by pre-Neolithic African hunter-gatherers, arguing that there is no evidence of words in Proto-Afroasiatic related to agriculture or animal husbandry. Christopher Ehret, O. Y. Keita, and Paul Newman also argue that archaeology does not indicate a spread of migrating farmers into Africa, but rather a gradual incorporation of animal husbandry into indigenous foraging cultures. A significant minority of scholars supports an Asian origin of Afroasiatic, most of whom are specialists in Semitic or Egyptian studies. Prominent in this camp is the linguist Alexander Militarev, who argues that Proto-Afroasiatic was spoken by early agriculturalists in the Levant and subsequently spread to Africa. Militarev associates the speakers of Proto-Afroasiatic with the Levantine Post-Natufian Culture, arguing that the reconstructed lexicon of flora and fauna, as well as farming vocabulary indicates that Proto-AA must have been spoken in this area. Scholar Jared Diamond and archaeologist Peter Bellwood have taken up Militarev's arguments as part of their general argument that the spread of linguistic macrofamilies (such as Indo-European, Bantu, and Austro-Asiatic) can be associated with the development of agriculture; they argue that there is clear archaeological support for farming spreading from the Levant into Africa via the Nile valley. Phonological similarities Afroasiatic languages share a number of phonetic and phonological features. Consonant systems Afroasiatic languages all contain stops and fricatives; some branches have additional types of consonants such as affricates and lateral consonants. AA languages tend to have pharyngeal fricative consonants, with Egyptian, Semitic, Berber, and Cushitic sharing ħ and ʕ. In all AA languages, consonants can be bilabial, alveolar, velar, and glottal, with additional places of articulation found in some branches or languages. Additionally, the glottal stop () usually exists as a phoneme, and there tends to be