Abstract. Whether non-human animals can experience complex emotions like jealousy remains debated. In humans, jealousy is particularly salient in sibships,

Swiss birth data from 1750 to 1870 reveal that girls who had lots of older brothers close to their own age were less likely to survive than were those who did not.

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 ...