Self-domestication in non-human species: elephants as a case study

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Humans are unique in their sophisticated culture and diverse societal structures, their complex languages, and their extensive use of tools. According to the human self-domestication hypothesis, this unique set of traits may be the result of an evolutionary process of self-induced domestication, in which humans have evolved to be less aggressive and more cooperative. Notably, the only other species that has been argued to be self-domesticated besides humans so far is bonobos, resulting in a narrow scope for investigating this theory beyond the primate family. Here, we propose a new animal model for studying self-domestication: the elephant. First, we support our hypothesis with an extensive cross-species comparison which suggests that elephants indeed exhibit many of the features associated with self-domestication (e.g., reduced aggression, increased prosocial behavior, extended juvenile period, increased play behavior, socially regulated cortisol levels and complex vocal behavior). Next, we present novel genetic evidence to reinforce our proposal, showing that genes positively selected in elephants are enriched in pathways associated with domestication traits and include several candidate genes previously associated with domestication. Together, our findings underpin the idea that elephants, like humans and bonobos, may have been self-domesticated.