Educational Simulations:
This collection contains simulations of the evolution of direct reciprocity (food sharing in vampire bats), incest avoidance, selective infanticide (langurs), and an example of frequency dependent selection (hawk-dove game).  Download Educational Simulations

Generosity evolves:
Delton, Krasnow, Cosmides & Tooby (2011) found that when direct reciprocity evolves under ecological uncertainty the result is surprisingly generous organisms.  See for yourself: Download simulation & source code