Concerns about declining trust and rising cynicism are recurrent in academic research and the media.
Yet, prior studies focused on explaining, rather than predicting, temporal changes in trust. We tested
prediction models of trust change across (up to) 98 countries over six measurement waves (from 1981
to 2014). We tested whether different ecological predictors (e.g., pathogen prevalence, population
diversity, inequality) explain the past and predict future trust levels across countries. We used societal
growth curve models to disentangle between- from within-country effects and evaluated the accuracy
of the models’ out-of-sample predictions using the train-test split method: We used data from 1981–
2009 to “train” the models and obtain predictions of trust for the period of 2010–2014. None of our
models was more accurate in predicting future trust than a simpler baseline model. Moreover, we did
not observe a universal decline in trust. Instead, temporal changes in trust were country-specific,
highlighting the locality of cultural change. Most ecological predictors were correlated with between-country
differences in trust. Only resource availability and moral opinion polarization were associated
with within-country changes in trust: Countries that became less wealthy and more morally polarized
over time also became less trustful. These results highlight important differences between explanatory
and predictive models and suggest that ecological theories of trust might be of limited use when
predicting future cultural shifts.