@unpublished{publication-5710,
	author={Fehr, Ernst and Henrich, Joseph},
	institution={University of Zurich},
	issn={1424-0459},
	number={No. 140},
	series={Working paper series / Institute for Empirical Research in Economics},
	title={Is Strong Reciprocity a Maladaptation? On the Evolutionary Foundations of Human Altruism},
	year=2003,
}