Altruistic behavior as a costly signal of general intelligence

Unconditional altruism is an enduring puzzle for evolutionary approaches to social behavior. In this paper, we argue that costly signaling theory, a well-established framework in biology and economics, may be useful to shed light on the individual diVerences in human unconditional altruism. Based on costly signaling theory, we propose and show that unconditional altruistic behavior is related to general intelligence. The cost incurred by engaging in unconditional altruism is lower for highly intelligent people than for less intelligent people because they may expect to regain the drained resources. As a result, unconditional altruism can serve as an honest signal of intelligence. Our Wndings imply that distinguishing altruistic behavior from cooperative behavior in social psychological and economic theories of human behavior might be useful and that costly signaling theory may provide novel insights on various individual diVerence variables. © 2006 Elsevier Inc. All rights reserved.