One of the major achievements of African historical scholarship in the postcolonial period has been to show that ethnic identities, such as Yoruba, were socially shaped, processually unfolding entities, rather than static remnants of a primordial past. Over the same period a considerable scholarly and scientific literature developed about mental illness in southwest Nigeria, which focused on the Yoruba, the region's predominant ethnic group (Leighton, Lambo, Hughes, Leighton, Murphy, and Macklin 1963; WHO 1979; Westley 1993). Like Yoruba identity, which must be defined processually, groups and categories such as “the schizophrenias” are not primordial or unchanging entities. Much of the antipsychiatric literature that flourished in the 1960s erred in concluding that these categories were “only” myths, or therefore not “real” illnesses. To show that these categories are “in motion” is not to deny their reality or force for patients and caregivers, any more than to emphasize the historically formed character of ethnicities and national identities negates their subjective power.

A central proposition of many cross-cultural studies of mental disorders is that the illnesses are homogeneous but that the content varies in different cultural settings (Leighton et al. 1963). This tenet emerges from the important and rigorous task of forging a globally usable nosology and overturning a naïve form of cultural relativism. But one effect of this proposition has been to push considerations of content into the background. This chapter seeks to historicize and instantiate the reasons why content and context matter in the case of southwest Nigeria.