Primates have irreplaceable roles in cultural, scientific, and ecological systems, yet nearly two-thirds of species are threatened with extinction. While the natural processes involved in primate community assembly are well known, we understand less about the role humans play in influencing associated patterns of diversity. Here, we examine the unresolved relationships between anthropogenic activities, spatial and environmental filters, and patterns of primate diversity by assessing species richness across the Afrotropical, Indomalayan, Malagasy, and Neotropical realms. We found regional differences in the predictors associated with primate diversity. Fragmentation and mammalian defaunation were the most important disturbance variables and either independently or synergistically contributed to observable patterns of lower species richness in all realms except Madagascar. In the midst of a current biodiversity crisis, understanding macroscale patterns of diversity and the role humans play in altering these are critical for preserving biodiversity and preventing further declines.