Although social grooming is observed in many animal species, the grooming activities undertaken by primates are not strictly for the elimination of parasites. In primates, grooming is a social activity that strengthens relationships. The amount of grooming taking place between members of a troop is a potent indicator of alliance formation or troop solidarity. Robin Dunbar suggests a link between primate grooming and the development of human language. The size of the neocortex in a primate's brain correlates directly to the number of individuals it can keep track of socially, be it a troop of chimps or a tribe of humans.