Increased rigidity with age in social behavior of Java-monkeys (Macaca fascicularis)

Area of Science:

• Behavioral Science
• Primatology
• Neuroscience

Background:

• Aging impacts social behavior and information processing in non-human primates.
• Dominance hierarchy and stress (cortisol) may influence age-related behavioral changes.
• Understanding these changes is crucial for primate welfare and social dynamics.

Purpose of the Study:

• To investigate the effects of aging on behavioral structure in socially housed Java-monkeys.
• To assess how dominance history influences age-related behavioral modifications.
• To explore the impact of aging on information processing during social interactions.

Main Methods:

• Calculated sequential structure indices of individual and interactive behavior using information statistics.
• Assessed behavioral predictability in response to social partners.
• Compared young and old Java-monkeys with varying dominance histories.

Main Results:

• Old Java-monkeys with low dominance histories exhibited increased rigidity in their ongoing behavior.
• Old Java-monkeys with high dominance histories showed no significant behavioral changes compared to young monkeys.
• Older monkeys displayed reduced predictability in social interactions, particularly with unfamiliar individuals.

Conclusions:

• Dominance history modulates the effects of aging on behavioral rigidity in Java-monkeys.
• Aging impairs the ability to maintain behavioral predictability with unfamiliar social partners.
• These findings provide insights into the mechanisms underlying social withdrawal in aging non-human primates.