The Evolution of Self-Control in the Brain

Temptation and self-control evolved as single mechanism to make humans behave against their own self-interest. I analyze the evolution of self-control in a principal-agent framework, in which the agent has access to private information but his utility cannot depend on all rel-evant variables. The principal can obtain the first best asymptotically by biasing the utility of the agent (from which an endogenous conflict emerges) and simultaneously endowing the agent with a limited amount of self-control.Several empirical properties of self-control, observed in psychological experiments, are explained in terms of the model: 1) self-control grows over time as it is exercised; 2) self-control is lower when the level of glucose in the blood is low, but does not depend on a physical resource; 3) as the environment becomes more tempting, individuals exhibit less self-control. The model sheds light on the di?erence between self-control and hyperbolic discounting and provides a framework for understanding the recent surge of chronic non-communicable diseases, suggesting that the current environment could be welfare-reducing.