In his book “The Descent of Man” (1871), Darwin suggested that differences between human and animal intelligence is a matter of degree, not of kind. Since then, it has been empirically proven that Humans share common cognitive attributes but also exhibit complex cognitive skills not demonstrated by other primates. A crucial question in comparative cognitive research is whether these species differences in cognitive abilities correlate with differences in ecological and social factors. The social intelligence hypothesis suggests that an increase in social complexity drove the evolution of cognitive flexibility in primates. Comparisons using established cognitive tests between species that live in social systems of differing social complexity offer the strongest test of the social intelligence hypothesis but these comparisons are lacking. To fill this gap, ´Macacognitum´ will challenge the social intelligence hypothesis and will use a unique approach by comparing the cognitive skills of macaque species of different social tolerance grades using a large comprehensive test battery for comparative cognition. According to the theory, we should observe different set of cognitive abilities between the macaques. In particular, given their similar life history and diet, but different social styles, we expect macaques with a greater social tolerance to display greater skills in the social domain. Here, the integration of comparative psychology and evolutionary biology will: 1) help understand the evolutionary history of cognitive traits in a primate monophyletic group and 2) examine the differential influence of social style on cognition of closely related species. This project proposes a unique approach that has the potential to greatly improve our understanding of the evolutionary dynamics of human and non-human primate intelligence.