Data from: Stronger social bonds do not always predict greater longevity in a gregarious primate

In group-living species, individuals often have preferred affiliative
social partners, with whom ties or bonds can confer advantages that
correspond with greater fitness. For example, in adult female baboons and
juvenile horses, individuals with stronger or more social ties experience
greater survival. We used detailed behavioral and life history records to
explore the relationship between tie quality and survival in a gregarious
monkey (Cercopithecus mitis stuhlmanni), while controlling for dominance
rank, group size, and life history strategy. We used Cox proportional
hazards regressions to model the cumulative (multi-year) and current
(single-year) relationships of social ties and the hazard of mortality in
83 wild adult females of known age, observed 2–8 years each (437
subject-years) in eight social groups. The strength of bonds with close
partners was associated with increased mortality risk under certain
conditions: Females that had strong bonds with close partners that were
inconsistent over multiple years had a higher risk of mortality than
females adopting any other social strategy. Within a given year, females
had a higher risk of death if they were strongly bonded with partners that
changed from the previous year versus with partners that remained
consistent. Dominance rank, number of adult female groupmates, and age at
first reproduction did not predict the risk of death. This study
demonstrates that costs and benefits of strong social bonds can be
context-dependent, relating to the consistency of social partners over
time.