s38.
Robert Barton and Robin Dunbar (1997), “Evolution of the Social Brain”, in Andrew Whiten and Richard W. Byrne, eds. (1997), Machiavellian Intelligence II, p 255. The ability to keep up with relations between other members in your group is what is termed Machiavellian intelligence. The classic description of primate politics in action is Frans de Waal (1982), Chimpanzee Politics.