 In the second interpretation, agents themselves do not learn, but rather the strategies grow or shrink in the population according to the reproductive advantages that they bestow upon the agents that adhere to them. This interpretation requires very long timescales, as it requires many generations of agents before equilibrium is reached. The typical dynamics that are considered in such circumstances come from biology. A standard approach is something like the replicator dynamic. Norms grow or shrink in proportion to both how many agents adhere to them at a given time, and their relative payoffs. More successful strategies gain adherents at the expense of less-successful ones. This evolutionary process assumes a constant-sized (or infinite) population over time. This interpretation of an evolutionary dynamic, which requires long timescales, raises the question of whether norms themselves evolve slowly. Norms can rapidly collapse in a very short amount of time. This phenomenon could not be represented within a model whose interpretation is generational in nature. It remains an open question, however, as to whether such timescales can be appropriate for examining the emergence of certain kinds of norms. While it is known that many norms can quickly come into being, it is not clear if this is true of all norms.