I've written before about the survival instinct being the fundamental driving force behind the capitalist economic system, increasing & maintining wealth, and hence the resulting advantage obtained by capital over labor.  The following linked article restates my thesis using the "insurance" incentive in place of survival instinct, but they are one in the same, having the same objective.  The author proposes, and makes his case, that there's a strong relationship between the insurance incentive (survival instinct) income/wealth inequality and productivity & employment.  http://www.interfluidity.com/v2/3487.html