Fairness Versus Reason in the Ultimatum Game
Science 8 September 2000:
Vol. 289. no. 5485, pp. 1773 - 1775
DOI: 10.1126/science.289.5485.1773
In the Ultimatum Game, two players are offered a chance to win a certain sum of money. All they must do is divide it. The proposer suggests how to split the sum. The responder can accept or reject the deal. If the deal is rejected, neither player gets anything. The rational solution, suggested by game theory, is for the proposer to offer the smallest possible share and for the responder to accept it. If humans play the game, however, the most frequent outcome is a fair share. In this paper, we develop an evolutionary approach to the Ultimatum Game. We show that fairness will evolve if the proposer can obtain some information on what deals the responder has accepted in the past. Hence, the evolution of fairness, similarly to the evolution of cooperation, is linked to reputation.
* To whom correspondence should be addressed. E-mail: nowak@ias.edu
Altruism may arise from individual selection
Journal of Theoretical Biology
Volume 235, Issue 2, 21 July 2005, Pages 233-240
Abstract Full Text + Links PDF (282 K)
Altruism may arise from individual selection
Angel Sánchez
, 
and José A. Cuesta
Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matemáticas, Universidad Carlos III de Madrid, 28911 Leganés, Madrid, Spain
Received 23 July 2004; revised 23 November 2004; accepted 11 January 2005. Available online 5 March 2005.
Abstract
The fact that humans cooperate with non-kin in large groups, or with people they will never meet again, is a long-standing evolutionary puzzle. Altruism, the capacity to perform costly acts that confer benefits on others, is at the core of cooperative behavior. Behavioral experiments show that humans have a predisposition to cooperate with others and to punish non-cooperators at personal cost (so-called strong reciprocity) which, according to standard evolutionary game theory arguments, cannot arise from selection acting on individuals. This has led to the suggestion of group and cultural selection as the only mechanisms that can explain the evolutionary origin of human altruism. We introduce an agent-based model inspired on the Ultimatum Game, that allows us to go beyond the limitations of standard evolutionary game theory and show that individual selection can indeed give rise to strong reciprocity. Our results are consistent with the existence of neural correlates of fairness and in good agreement with observations on humans and monkeys.
Keywords: Strong reciprocity; Individual selection; Evolutionary theories; Behavioral evolution; Evolutionary game theory