Before revision:  We show that the natural scale over which collective attention fades is inversely proportional to the frequency of use of the verbs .
After revision:  We show that the natural scale over which collective attention fades is in inverse proportion to the verb frequency. The integration of the two basic mechanisms of imitation and attention to novelty allows to understand diverse competing objects, with lifetimes that range from hours for memes and news (7, 8) to decades for verbs. This suggests a general mechanism underlying cultural evolution .