Mentalising mechanisms underly strategic coordination in Guinea baboons (Papio papio)

It remains controversial whether the ability to mentalise is confined to humans. To address this question, Guinea baboons living in a social colony freely came to play a 2-players coordination game with any other baboon, or alone (social vs solo conditions). In fact, in both conditions, they interacted with an identical Artificial Agent. Their choice behaviour depended on the social context and their relative dominance hierarchy. A mentalising computational model accounted for baboons' behaviour better than simpler models without mentalizing components in the social condition while the same baboons used a simpler strategy when they played alone. Together, these findings indicate that computations required for mentalising and used for coordination learning may have evolved in the common ancestor of the Old-World monkey and apes.