jats:pDiscussions of domestication and its associated genetic traits has focused upon dispersal mechanisms, for example in the rachis structure of cereals. Here we consider another trait of importance to domesticated crops – their seasonality response. We particularly consider flowering response to changing daylength, and how that relates to domesticated species that are carried by farmers considerable distances from their regions of origin. We consider the implications of cultivating crops in regions whose seasonality patterns contrast with those of the crop’s region of origin, and consider the consequent genetic changes. Reference is made to the particular case of barley, and a discussion of archaeogenetic research into its photoperiod response mechanism is provided.</jats:p>