Abstract

Conventional demographic models systematically overestimate fertility decline in sub-Saharan Africa. This paper proposes a complementary explanation grounded in a prevalent but understudied belief system: ancestors influence the living and seek the continuation of their lineage, into which they may be reincarnated. In this worldview, having children becomes a moral and collective duty, rooted in the spiritual responsibility to ensure the survival of the lineage. Drawing on first-hand data, novel ethnographic information, and historical and contemporary surveys, I document a strong and quantitatively large positive relationship between ancestral beliefs and fertility across contexts and time periods. A simple model in which children are a public good for the lineage rationalizes the patterns observed in the data: the fertility effect of ancestral beliefs is concentrated in patrilineal societies, and a specific form of free-riding emerges among siblings whose children continue the same family line. These findings suggest that high fertility in sub-Saharan Africa rests on moral foundations that standard, externally designed interventions tend to overlook.