“A study by Massachusetts General Hospital (MGH) investigators has discovered two groups of neurons that play key roles in social interactions between primates – one that is activated when deciding whether to cooperate with another individual and another group involved in predicting what the other will do. Their findings appear in the March 12 issue of Cell.”
In this study, pairs of Rhesus monkeys repeatedly played a version of the Prisoner’s Dilemma game. The most remarkable result of the study is that the ‘predictor neurons’ of monkey A predicted the choices of monkey B as accurately as a ‘rational’ algorithm that tried to predict the choices of monkey B based on his/her prior choices. Here is a beautiful article on the Prisoner’s Dilemma and its role in Evolutionary Biology from Quanta Magazine.