"Fair" outcomes without morality in cleaner wrasse mutualism

Abstract

Baumard et al. propose a functional explanation for the evolution of a sense of fairness in humans: Fairness preferences are advantageous in an environment where individuals are in strong competition to be chosen for social interactions. Such conditions also exist in nonhuman animals. Therefore, it remains unclear why fairness (equated with morality) appears to be properly present only in humans.