My hunch is that environmental harshness plays a crucial role in the development of 'trust to strangers', both being widely variable. Sharing resources shows th

My hunch is that environmental harshness plays a crucial role in the development of 'trust to strangers', both being widely variable. Sharing resources shows there could be more from that source and the receiver could go to great lengths to strip the giver of his possessions if it is less investment than to try to aquire them by other means, thus working against trustfulness and making ultra-selfishness a better stable strategy in certain conditions. It is undeniable that cunning and deceit evolved alongside cooperation, if not preceding it. Even a little difference in initial conditions could be significant. It's not apparent that the simulation accounts for that.