Despite the evident challenges posed by arctic environments past and present, and despite the widespread acknowledgement that human population histories in the Arctic have historically been quite dynamic, it is often assumed that traditional pre-colonial populations were in perfect equilibrium with their environment, that they were perfectly adapted to their local environmental conditions.

This adaptationist assumption is strongly challenged by recent research in ecology that has shown that many high-latitude ecological communities are in fact far from equilibrium with environmental conditions. Here we briefly introduce the notion of disequilibrium and the papers making up this special section. Ranging from the European Palearctic to the predicaments faced by contemporary populations in the circumpolar North, this collection presents a solid comparative evidence base for this new perspective.

Together, these papers underline that adaptation – defined classically as the outcome of selection matching a particular feature or behaviour to the social or natural environment – cannot be assumed but needs to be empirically demonstrated. The papers also offer numerous qualitative and quantitative avenues for how to conduct such empirical investigations.