Altruism and Spite in a Selfish Gene Model of Endogenous Preferences

Abstract

Economists and biologists have long grappled with the apparent contradiction of altruism in a naturally-selected world. Standard economic models are built upon an assumption of material self-interest where agents maximize individual outcomes without regard for the effects on others. This paper begins with a brief discussion of the evidence that human behavior deviates from the economic assumption. With the goal of more accurately describing human nature, the interpersonal components of preferences are derived in a genetic model. This model predicts a variety of behaviors that are considered paradoxical within the standard economic framework. The optimal attitude towards others is parameterized by the genetic relationship between individuals and by the population size. For interactions between ‘average’ individuals, the standard economic assumption is the limiting case of the genetic model as the population becomes arbitrarily large.