Leveraging ethological studies on the Macaca genus, 23 species have been ordered on a 4-grade social tolerance scale based on 18 behavioural traits, including counter-aggression and reconciliation rates (Grade 1, e.g., M. mulatta, to Grade 4, e.g., M. tonkeana). However, the neuroanatomical correlates of interspecific differences in macaques’ social behaviours remain unknown. To address this, we fostered a unique collection of 34 post-mortem samples from 11 macaque species, combining Strasbourg-based 7T MRI scans with data from existing databases (PRIMate Data Exchange, Japan Monkey Centre, Oxford University). Analyzing subcortical anatomy (SARM atlas) in light of recent research on primates' social brain, we built on previous findings in intolerant macaque species, revealing correlations between subcortical region volumes and socio-demographic variables. We hypothesized that volumetric variations in social brain regions mirror social tolerance, our results identify a correlation between the amygdala's volume and macaque social grades. Tolerant macaques exhibit larger amygdala nuclei than intolerant ones, particularly noticeable during early life stages. These findings provide unprecedented insights into cross-species neuroanatomical correlates of social behavior in primates. The results, highlighting the amygdala's role in social cognition and behavior regulation, pave the way for future investigations into cortical structures (anatomical and functional) and the evolutionary aspects of the primate social brain.