Age- and sex-dependent associations between the number of older siblings and early-life survival in pre-industrial humans.

Siblings are an important part of an individual's early-life environment and may therefore play an important role in shaping an individual's survival. The quantification of sibling effects on survival is challenging, however, especially in long-lived species with extended parental care and overlapping generations, such as humans. Here, we use historical parish data from Switzerland to quantify how the number of older siblings and their survival status, age and sex are associated with childhood survival.