•We introduce the concept of crucial ‘domestication syndrome’ (DS) traits.•Crucial DS traits are part of the features distinguishing crops from wild forms.•The crucial DS concept improves understanding of prehistoric domestication episodes.•Using the crucial DS concept may enhance future crop improvement capacity. ‘Domestication syndrome’ (DS) denotes differences between domesticated plants and their wild progenitors. Crop plants are dynamic entities; hence, not all parameters distinguishing wild progenitors from cultigens resulted from domestication. In this opinion article, we refine the DS concept using agronomic, genetic, and archaeobotanical considerations by distinguishing crucial domestication traits from traits that probably evolved post-domestication in Near Eastern grain crops. We propose that only traits showing a clear domesticated–wild dimorphism represent the pristine domestication episode, whereas traits showing a phenotypic continuum between wild and domesticated gene pools mostly reflect post-domestication diversification. We propose that our approach may apply to other crop types and examine its implications for discussing the timeframe of plant domestication and for modern plant science and breeding.