Witchcraft is one of the manifestations of envy. It has disruptive effects on team work. A fold catastrophe is shown to exist between the degree of envy and the productivity of the witch's victim. The big eye effect is the discontinuous dip in productivity, driven by an increase in envy. There...

This paper proposes a model that unifies and integrates four conjectures put forward to explain the extinction of the Neanderthals. The model shows that these hypotheses, considered together or individually, are not sufficient to guarantee the extinction of the Neanderthals. Moreover, a survival...