Some 15 years ago, the American political scientist Robert Axelrod put forward a remarkable model of the way cultural diversity persists in society. His idea was that people are more likely to interact with others like them. The more similar two people are, the more likely they are to adopt each other’s traits. 

That’s how traits spread but it is also why diversity persists. 

Since then, the power and simplicity of Axelrod’s approach has led complexity theorists to study numerous variations on the original theme. The model lends itself to computer simulation because people can be modelled as nodes on a grid influenced by those closest to them. Whatever the starting conditions, a computer can go through through millions of iterations to see how traits spread. 

Consequently, Axelrod’s approach has been used to simulate behaviours ranging from the spread of language to voting behaviour.

Today, Bartlomiej Dybiec and pals at the Center for Models of Life in Copenhagen use an Axelrod-like model to examine the way cultures might have spread throughout Europe. They think about culture as a collective term for rumours, stories, ideas and fashions which are shared by people at the same location.  

The culture spreads when people at a nearby location adopt a newer set of fashions. Cultural centres survive by rebroadcasting the same fashions or repackaging old ones as new. 

Where Dybiec and co differ from Axelrod is in assuming there is a small chance that a new fashion can spontaneously arise at any location and then spread like ripples across a pond. And instead of using a square grid (or some other regular shape) they superimpose their model onto a map of Europe.

Clearly, Europe’s geography places strict limits on the way cultures can spread (assuming that fashions cannot jump across water). This has important implications.

For example, Dybiec and co’s model suggests that the borders between regions dominated by different cultures can change very quickly. Their maps of Europe change over a period equivalent to 50 years or so. That’s exactly as has happened, even in the recent past. 

But these guys’ main conclusion is that cultural centres survive longest in geographically remote regions, particularly peninsulas such as Greece and Italy. That’s because it is hard for new cultures to spread into these regions. 

So, it’s of more than passing interest that these regions gave birth to two of the greatest and long-lived cultures in human history–the ancient Greek and Roman empires. It also backs the idea put forward by Jared Diamond in his book Guns, Germs and Steel that the fortunes of the western world are largely the result of an accident of geography. 

Of course, Dybiec and co’s model is simplistic in the extreme. It makes no allowance for the possibility that culture might spread overseas and does not take into account the effects of other geographical constraints such as rivers, mountains and climate. 

But these are nuances that, presumably, can be added into the model as it becomes more complex.  

Dybiec and co describe their model as replaying the history of Europe. It’ll be interesting to see what the next replay reveals. 

Ref: arxiv.org/abs/1201.3052: Information Spreading And Development Of Cultural Centers