[PatrickHenry]

I'll check this thread tomorrow for your results and a copy of your program to verify that it does what you claim.

Tomorrow has arrived. Here's a link to a well-known alternative model.

[Doctor Stochastic]

I'll look at this later. I first thought of throwing a big grid over the whole Earth (vide Puck in "Midsummer Night's Dream") then using a diffusion based movement from cell to cell. It's probably better just to choose interesting places and put population there. An incidence matrix gives the migration routes and these are where the population (and genetic and linguistic) movements take place. Places like Europe would have many nodes and the Atlantic Ocean very few.