Where do demonstratives come from?

Studies in grammaticalization have established that processes of grammatical change frequently have lexical items as their source, and more specifically nouns and verbs. But there is at least one potential exception: As argued by Holger Diessel in a number of publications, demonstratives cannot be historically derived from other entities, such as lexical items. Based on a survey of languages from different parts of the world and belonging to different language families, the present paper argues that this generalization is in need of reconsideration.