In evolutionary medicine and other related fields, the concept of evolutionary mismatch is used to explain phenomena whereby traits reduce in adaptive value and eventually become maladaptive as the environment changes. This article argues that there is a similar problem of persistent adaptivity—what has been called the problem of evolutionary novelty—and it introduces the concept of mismatch resistance in order to explain phenomena whereby traits retain their adaptive value in novel environments that are radically different from the organisms’ environment of (...) evolutionary adaptedness (EEA). The possible role of variability selection in the evolution of mismatch-resistant traits is discussed, and it is suggested that mismatch resistance provides a useful tool for making progress on certain issues related to evolutionary theory, such as the modularity debate, cases of adaptivity outside of organisms’ ancestral environment, and the viability of naturalism as an overarching philosophical framework for understanding the natural world. (shrink)