The 89th Annual Meeting of the American Association of Physical Anthropologists (2020)

The role of dispersal and school attendance on reproductive dynamics in small populations


1Anthropology, University of Utah, 2Anthropology, Eastern Carolina University, 3Economic Science Institute, Chapman University, 4Psychology, Arizona State University

April 16, 2020 23, Platinum Ballroom Add to calendar

Individuals from small populations face challenges to initiating reproduction because stochastic demographic processes create local mate scarcity. In response, flexible dispersal patterns facilitating the movement of individuals across groups are argued to reduce mate search costs and inbreeding depression. Furthermore, factors that aggregate dispersed populations, such as rural schools, could lower mate search costs through expansion of mating markets. However, research typically suggests that dispersal and school attendance are costly, causing individuals to delay marriage and reproduction. Here, we investigate the role of dispersal and school attendance on marriage and reproductive outcomes in four small, dispersed ranching populations in Baja California Sur, Mexico. Our analyses yield the following results. First, we find no evidence that dispersal increases the age at marriage or first reproduction for women. For men, dispersal results in younger ages of marriage than those who remain natal. Second, we find that dispersal increases genetic relatedness among marriage partners. This is likely a mechanism to establish social support for raising offspring in novel communities. Third, counter to typical results for the role of education on reproductive timing, attending school serves to lower age at marriage for both sexes and to lower age at first birth for women. Factors like dispersal and school attendance, that are typically associated with delayed reproduction in large populations, actually lower mate search costs in small, dispersed populations with minimal access to labor markets. We highlight the relevance of population size for understanding the generalizability of reproductive dynamics.