Does anybody know when and how linguistic negation was manifested in proto-language (anyone, for example, proto-indo-european)?
What is meant by "linguistic negation" is these patterns of language that include negative references, i.e "not this", "not that".
References would be great as well. Thanks.
The post by @TKR on Diachronic sources of negators approaches the spirit of the question, but it is not what is asked here. The question is about initial manifestation (and historical evolution) of negation in language (part of a greater study of negation, including linguistics)