This is a simulation of the basic demographic / genealogical process. Individuals are born and individuals die. This causes lineages to branch and to disappear, and causes the population to share a common ancestor at some time in the past. The coalescent provides a mathematical description of these patterns of ancestry.
Individuals are represented as circles. Layout is taken care of through simple physics. Each individual is given a charge and Coulomb's law is used to for repulsion. The edges of the screen are also charged.
Individuals leave a trace of where they used to be. I was pleasantly surprised to have the physical location of a lineage cleanly reveal its genealogical history.
Press H to bring up a listing of commands. Running this in the browser is significantly slower than running it as its own application. Also, fonts are kind of broken by the browser for some reason. You can download executables and source code if you'd like.