Barley grown in Scandinavian countries has adapted like reindeer have to cope with extremes of day length at high latitudes. A genetic mutation in Scandinavian barley varieties disrupts the circadian clock. Just as reindeer have dropped the clock in adapting to extremely long days, so has Scandinavian barley to grow successfully in the short growing season. This new knowledge may be useful in efforts to adapt crops for regions where the growing season is short.