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Updated: Jun 12, 2026
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The Resident-intruder Paradigm: A Standardized Test for Aggression, Violence and Social Stress
Published on: July 4, 2013
Aggression does not increase friendly contacts among bystanders in geladas (Theropithecus gelada).
Alessia Leone1, Michele Mignini, Giada Mancini
1Centro Interdipartimentale Museo di Storia Naturale e del Territorio, Natural History Museum, University of Pisa, Pisa, Italy.
Primates; Journal of Primatology
|June 24, 2010
Summary
Researchers investigated "quadratic affiliations" in geladas after conflicts. They found no evidence that witnessing aggression increases social bonding between bystanders to reduce tension, unlike in hamadryas baboons.
Area of Science:
- Primatology
- Ethology
- Social Behavior
Background:
- Aggression within social groups can influence bystander interactions.
- Post-conflict affiliations, termed 'quadratic affiliations', may reduce tension.
- This behavior has been observed in hamadryas baboons.
Purpose of the Study:
- To investigate the presence of quadratic affiliations in geladas (Theropithecus gelada).
- To determine if witnessing aggression increases bystander affiliation in geladas.
- To assess if tension-reducing behaviors are affected by conflict observation.
Main Methods:
- Employed the post-conflict/matched control (PC/MC) method.
- Collected behavioral data on 192 PC/MC pairs of adult and immature geladas.
- Analyzed affiliation levels, yawning, and self-scratching behaviors during post-conflict and control periods.
Main Results:
- No significant increase in bystander affiliation levels was observed during post-conflict (PC) compared to matched control (MC) conditions.
- Kinship and relationship quality did not influence the distribution of quadratic interactions.
- Yawning and self-scratching behaviors showed no variation between PC and MC conditions.
Conclusions:
- Geladas do not exhibit quadratic affiliations as a tension-reduction mechanism after witnessing aggression.
- High male tolerance and social cohesiveness in geladas may prevent sufficient bystander tension.
- Witnessing fights does not appear to induce stress leading to affiliative bonding in gelada bystanders.
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