By José Manuel Galán

& Luis R. Izquierdo



In this website you will find all the information about our work trying to replicate the simulation results reported by Axelrod (1986) in an influential paper on the evolution of social norms. Basically our study shows that Axelrod’s results are not as reliable as one would desire. We can obtain the opposite results by running the model for longer, by slightly modifying some of the parameters, or by changing some arbitrary assumptions in the model. Of course, we can only say that almost 20 years after Axelrod published his paper: the computational power required to undertake our study was just not available in 1986.  The real interest of this re-implementation exercise is that it has allowed us to draw some best-practice guidelines that you may find useful when developing and analysing your agent-based models. In particular, we illustrate the importance of running stochastic simulations several times for many periods, of exploring the parameter space adequately, of complementing simulation with analytical work, and of being aware of the scope of our simulation models.


Use the menu on the left to download RAEAN (Re-implementation of Axelrod's "Evolutionary Approach to Norms"). RAEAN is our agent-based model designed to replicate and extend Prof. Axelrod’s model. Also, you will find a user guide, an API (Application Programming Interface), an applet, and a link to our paper, where we present our work in detail.


We hope that you will find this piece of work useful!





Axelrod, R.M., 1986. "An evolutionary approach to norms", American Political Science Review 80, nº4, December 1986: 1095-1111. Reprinted in Axelrod, R. M., 1997. The Complexity of Cooperation. Agent-Based Models of Competition and Collaboration.  Princeton University Press. Princeton, New Jersey 1997.