The consequences of sibling rivalry on survival and reproductive success across different ecological contexts: a comparison of the historical Krummhörn and Quebec populations

This article investigates the relationship between large families and the probability of offspring survival, marriage, and fertility across the historical populations of the Quebec (1670-1799) and Krummhörn regions (1720-1874). Both populations exist in agriculturally based economies, but differ in important ways. The Krummhörn population faced a fixed supply of land, which was concentrated amongst a small number of farmers. Most individuals were landless agricultural workers who formed a relatively competitive labor supply for the large farmers. In contrast, individuals in Quebec had access to a large supply of land, but with far fewer available agricultural workers, had to rely on their family to develop and farm that land. Results indicate that more siblings of the same gender were generally associated with increases in mortality during infancy and childhood, later ages of first marriage, and fewer numbers of children ever born. For mortality and age at first marriage, the effects of sibling formation appear strongest in the Krummhörn region. This indicates that although sibship effects appear in both ecological contexts, that the context of the region mattered in determining their magnitude.