NetLogo User Community Models
by Max OrHai (Submitted: 12/02/2010)
WHAT IS IT?
This is an extremely simplified model of the influence of cultural or "memetic" trait transfer upon population dynamics, roughly corresponding to that first articulated in the book _Culture and the Evolutionary Process_ by Robert Boyd and Peter J. Richerson (1988), and put forward as a "paradigmatic example in memetics" by Derek Gatherer in the Journal of Memetics (2005). Rather than using an abstract recursive procedure involving the population proportions, however, this model uses individual interacting agents in a space. The spatial dynamics may be of interest: in particular, the formation of population source clusters under some conditions was a little surprising to me.
HOW IT WORKS
All agents move around in ten-step circles of size determined by their speed, and have hundred-step average lifetimes. They reproduce sexually at a rate determined by their fertility parameter when they are on the same patch as another agent, only when the global population cap and the local crowding tolerance permit. By sexual reproduction, I mean that either the agent or their randomly-selected partner makes a new agent the same type as the parent.
Homebodies are the brown turtles. They move slower and reproduce more.
I've tried to parameterize as much of the model as seemed reasonable so that you can tweak it while it's running, but there are a few hard-coded constants to play with in the procedures, if you're interested.
This isn't supposed to be a realistic model of any particular social phenomenon, but if one would like to get ones hands dirty, there are some very basic things to consider which aren't in the model, such as age, local resources, spatial barriers... plus, there might be more than two kinds of people (or traits, or both) in the world, and all sorts of interactions between traits both inherited and learned might be important. For that matter, there might even (hypothetically) be more kinds of interactions between people than just breeding and partying. If one wants to do science and not just goof off like the present author, then for heaven's sake follow Gatherer's advice and pick a subject where there's some good data against which one might verify the model.
Thanks to the Systems Science school at Portland State University for the Models in
Gatherer, D. (2005). Finding a Niche for Memetics in the 21st Century.
Boyd, R. and Richerson, P. J. (1985). Culture and the evolutionary process.
NetLogo is of course Copyright 2002 Uri Wilensky. 'All rights reserved', says he.
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