Proto-Anatolian is the proto-language from which the ancient Anatolian languages emerged (i.e. Hittite and its closest relatives). As with almost all other proto-languages, no attested writings have been found; the language has been reconstructed by applying the comparative method to all the attested Anatolian languages as well as other Indo-European languages. Craig Melchert, an expert on the Anatolian languages, estimates that Proto-Anatolian began to diverge c. 3000 BC, in any case no later than c. 2500 BC. Phonology For the most part, Proto-Anatolian has been reconstructed on the basis of Hittite, the best-attested Anatolian language. However, the usage of Hittite cuneiform writing system limits the enterprise of understanding and reconstructing Anatolian phonology, partly from the deficiency of the adopted Akkadian cuneiform syllabary to represent Hittite phonemes and partly from Hittite scribal practices. It is especially pertinent to what appears to be confusion of voiceless and voiced dental stops, in which signs -dV- and -tV- are employed interchangeably in different attestations of the same word. Furthermore, in the syllables of the structure VC, only the signs with voiceless stops are usually used. Distribution of spellings with single and geminated consonants in the oldest extant monuments indicates that the reflexes of Proto-Indo-European voiceless stops were spelled as double consonants and the reflexes of PIE voiced stops as single consonants. This regularity is the most consistent in the case of dental stops in older texts; later monuments often show irregular variation of this rule. Vowels Common Anatolian preserves the PIE vowel system basically intact. Some cite the merger of PIE */o/ and */a/ (including from *h₂e) as a Common Anatolian innovation, but according to Melchert that merger was a secondary shared innovation in Hittite, Palaic and Luwian, but not in Lycian. Concordantly, Common Anatolian had the following short vowel segments: */i/, */u/, */e/, */o/ and */a/. Among the long vowels, */eː/ < PIE *ē is distinguished from */æː/ < PIE *eh₁, with the latter yielding ā in Luwian, Lydian and Lycian. Melchert (1994) had also earlier assumed a contrast between a closer mid front vowel */eː/ < PIE *ey (yielding Late Hittite ī) and a more open */ɛː/ < PIE *ē (remaining Late Hittite ē), but the examples are few and can be accounted for otherwise. The status of the opposition between long and short vowels is not entirely clear, but it is known for certain that it does not keep the PIE