Human reasoning has been shown to be biased in a variety of situations. While most studies have focused on samples of WEIRD participants (from Western Educated Industrialized Rich and Democratic societies), the sparse non-WEIRD data on the topic suggest an even stronger propensity for biased reasoning. This could be explained by a competence issue (people lack the ability to integrate logical knowledge into their reasoning) or a performance issue (people possess the logical knowledge but do not know it is relevant). We addressed this question using a debiasing paradigm with the base-rate task on a sample of non-industrialized people, the Himba of Namibia. After a short training, most participants were debiased, lending credence to the performance account. Debiasing was however to some extent boosted by schooling and living environment suggesting that competence also plays a role (in that more acquired knowledge allows for a higher training benefit). Results imply that debias interventions can be successfully employed to boost sound reasoning around the world.