Robert McColl Millar is Professor of Linguistics and Scottish Language at the University of Aberdeen, Scotland. He has published widely on, amongst other things, linguistic contact and rapid language change, the sociology of language, and dialectology. His most recent publications include Contact: The Interaction of Closely Related Linguistic Varieties and the History of English (2016) and A Sociolinguistic History of Scotland (2020). He has recently completed A History of the Scots Language, which will be published in 2023.

R L Trask was Professor of Linguistics at the University of Sussex, UK, and a leading authority on Basque language and historical linguistics. His book The History of Basque (1997) is an essential reference on diachronic Basque linguistics, and probably the best-known introduction to Basque linguistics. He also wrote about the problem of the origin of language and, amongst his other publications, the very successful foundational text, Language: The Basics (1995).