Map of Semitic languages and inferred dispersals. The locations of all languages sampled in this study, both extinct and extant, are depicted on the map. The current distribution of Ethiosemitic languages follows Bender (1971) and distribution of the remaining languages follows Hetzron (1997). The ancient distribution of extinct languages is also indicated (i.e. Akkadian, Biblical Aramaic, Ge'ez, ancient Hebrew and Ugaritic; Bender 1971; Hetzron 1997). The West Gurage (Chaha, Geto, Innemor, Mesmes and Mesqan) and East Gurage (Walani and Zway) Ethiosemitic language groups in central Ethiopia are depicted as two combined groups. The map also presents the dispersal of Semitic languages inferred from our study. An origin of Afroasiatic along the African coast of the Red Sea, supported by comparative analyses (Ehret 1995; Ehret et al. 2004), is indicated in red, although other African origins of Afroasiatic have been proposed (e.g. southwest Ethiopia; Blench 2006). The assumed location of the divergence of ancestral Semitic from Afroasiatic between the African coast of the Red Sea and the Near East is indicated in italics. Semitic dispersals are depicted by arrows coloured according to the estimated time of divergence (see coloured time scale at top of figure), and important nodes from the phylogeny (figure 2) are placed on the arrows to indicate where and when these divergences occurred.

Phylogeny of Semitic languages. Our phylogeny of 25 Semitic languages based on binary encoded data is presented with mean divergence times to the right of each node and 95% HPD intervals indicated by light grey bars. The scale bar along the bottom of the phylogeny presents time in YBP. Posterior probabilities of branches are printed in italics above each branch with >0.75 support. Extinct languages are underlined and all other languages are considered to evolve to the present. Subgroups of Semitic are identified by colour bars to the right of the phylogeny (purple bars, East Semitic; green bars, Central Semitic; red bars, MSA; and blue bars, Ethiosemitic) and by three boxes (West, Central and South Semitic). Important nodes are indicated by letters: A, West Semitic; B, Central Semitic; C, Ugaritic–Hebrew–Aramaic; D, Arabic; E, South Semitic; F, MSA; and G, Ethiosemitic. The dashed line leading to Arabic reflects the fact that log BF tests were equivocal in the placement of Arabic, so we placed Arabic in Central Semitic based on previous linguistic studies (e.g. Hetzron 1976; Faber 1997). The topology is rooted with Akkadian, which is preferred by our log BF analyses, and follows the constraints of the standard model.