Formal language must have developed very slowly, and there was time for innovations to spread from one horde to the next. Youngsters getting lost from their parents and starting up their own language would be another special mode of language creation, if it ever actually occurred. Wherever languages have similarities in phonetics, vocabulary, or grammatical structure, it is possible that they have had a common history—either that they were dialects of a single language or that the people who spoke them were neighbors for a substantial period of time. The overall comparison of the languages of the world suggests that doubling of consonants is an old and widespread process, as are the contrastive types that gave rise to the simple and glottalized or unvoiced and voiceless stops. When the world’s languages are compared and the degrees of interrelationship are used for setting up a meshed intergrading classification such as that suggested, an interesting pattern of distribution is revealed.