India, Feb. 21 -- Greed is a core aspect of human nature. Like many psychological traits, it is normally distributed within the population, meaning that the majority have intermediate greed, while a few are very minimally or excessively greedy. This individual tendency to greed, measurable using a variety of psychological assessments, tends to remain stable within a person over time, suggesting that it is largely hard-wired within our psyches, less susceptible to the vagaries of our experiences. And as with any such widespread human trait, there must be some sort of evolutionary directive for us to exhibit greed, not just to support the principles that underpin our modern societies. There must be some benefits that propagate greed through...