Pareto's law: a model of human sharing and creativity
  A computational model for the distribution of wealth among the members of an ideal society is presented. It is determined that a realistic distribution of wealth depends upon two mechanisms: an asymmetric flux of wealth in trading transactions that advantages the poorer of the two traders and a non-stationary creation and destruction of individual wealth. The former mechanism redistributes wealth by reducing the gap between the rich and poor, leading to the emergence of a middle class. The latter mechanism, together with the former one, generates a distribution of wealth having a power-law tail that is compatible with Pareto's law. 
Nicola Scafetta, Sergio Picozzi and Bruce J. West