The current investigation tested if people's basic belief in the notion that human beings have developed from other animals (i.e., belief in evolution) can predict human-to-human prejudice and intergroup hostility. Using data from the American General Social Survey and Pew Research Center (Studies 1-4), and from three online samples (Studies 5, 7, 8) we tested this hypothesis across 45 countries, in diverse populations and religious settings, across time, in nationally representative data (N = 60,703), and with more comprehensive measures in online crowdsourced data (N = 2,846). Supporting the hypothesis, low belief in human evolution was associated with higher levels of prejudice, racist attitudes, and support for discriminatory behaviors against Lesbian, Gay, Bisexual, Transgender, and Queer (LGBTQ), Blacks, and immigrants in the United States (Study 1), with higher ingroup biases, prejudicial attitudes toward outgroups, and less support for conflict resolution in samples collected from 19 Eastern European countries (Study 2), 25 Muslim countries (Study 3), and Israel (Study 4). Further, among Americans, lower belief in evolution was associated with greater prejudice and militaristic attitudes toward political outgroups (Study 5). Finally, perceived similarity to animals (a construct distinct from belief in evolution, Study 6) partially mediated the link between belief in evolution and prejudice (Studies 7 and 8), even when controlling for religious beliefs, political views, and other demographic variables, and were also observed for nondominant groups (i.e., religious and racial minorities). Overall, these findings highlight the importance of belief in human evolution as a potentially key individual-difference variable predicting racism and prejudice. (PsycInfo Database Record (c) 2022 APA, all rights reserved).