With or without the Help of Kin? - Cooperative Breeding between Natal Support, in-Law Opportunities, and Consanguinity

Kai Willfuehr, University of Oldenburg

Previous research in the framework of evolutionary anthropology which investigated the effect of kin in the C18-C19 population of the Krummhörn region has demonstrated that mortality of reproductive females was reduced by the presence of the mother-in-law. This positive effect was partly due to increased level of consanguinity which was common among landholding families which frequently intermarried in order to concentrate wealth. Consanguinity, however, is associated with reduced reproductive success because of increased risk of hereditary diseases and pedigree collapse. In this study I use multiple failure Cox survival models and Poisson regression to investigate the association between kinship composition and fertility (number of children born) and reproductive success (number of surviving children to adulthood), respectively, of 3,242 reproductive females born to 2,424 marriages contracted between 1720 and 1800. In particular, I investigate whether kin effects are affected by consanguinity and socio-economic-status. Preliminary results suggest that fertility was affected by the kin network composition. The presence of the mother-in-law had a fertility enhancing effect among the economic elite, but was also connected to increased infant but not child mortality; presumably due to shorter interbirth intervals. I find socio-economic-status differentials in kin effects, but mixed evidence that consanguinity mattered.

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 Presented in Session 183. Roles of Kinship: Demographic Outcomes and Methodology