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

Area of Science:

• Behavioral Ecology
• Primate Social Behavior
• Survival Analysis

Background:

• Group-living species often form preferred social partnerships.
• Strong social ties can confer fitness advantages, such as increased survival in some species.
• The relationship between social bond quality and survival in wild primates requires further investigation.

Purpose of the Study:

• To investigate the association between social tie quality and survival in a gregarious monkey species (Cercopithecus mitis stuhlmanni).
• To control for factors including dominance rank, group size, and life history strategy.
• To examine both cumulative and current year relationships between social ties and mortality risk.

Main Methods:

• Utilized detailed behavioral and life history records from 83 wild adult female monkeys.
• Observed subjects over 2-8 years each, accumulating 437 subject-years of data across eight social groups.
• Employed Cox proportional hazards regressions to model mortality risk in relation to social tie strength and consistency.

Main Results:

• Inconsistent strong social bonds over multiple years were linked to a higher mortality risk.
• Within a single year, changing social partners was associated with increased death risk compared to consistent partners.
• Dominance rank, group size, and age at first reproduction did not predict mortality risk.

Conclusions:

• The costs and benefits of strong social bonds are context-dependent, influenced by partner consistency over time.
• Social strategies involving stable, consistent partnerships may be more advantageous for survival in this species.
• This study reveals nuanced dynamics of social relationships and their impact on fitness in wild primates.