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Risk-taking incentives predict aggression heuristics in female gorillas
Nikolaos Smit1,2, Martha M Robbins2
1Department of Biology, University of Turku, Turku, Finland.
Elife
|August 22, 2025
Summary
Gorilla aggression dynamics reveal that rank-reinforcement is common, but social and reproductive factors influence targets. Group composition and female reproductive status shift competitive strategies in these primates.
Area of Science:
- Primate behavior and social dynamics
- Evolutionary biology
- Animal aggression
Background:
- Competition for resources is often expressed through aggression in social groups.
- Understanding the factors influencing competitive interactions is key to understanding social evolution.
- Previous research has not fully elucidated the nuanced drivers of aggression in gorilla societies.
Purpose of the Study:
- To investigate the factors that modulate competitive aggression among groupmates in gorillas.
- To determine how social context (group composition) and individual state (reproductive status) influence aggression targets.
- To explore the evolution of aggression heuristics in relation to environmental and social conditions.
Main Methods:
- Analysis of a long-term behavioral dataset spanning over two decades (since 1998).
- Observation of five wild groups across two gorilla species.
- Quantification of aggression direction relative to rank, group composition, and female reproductive status.
Main Results:
- Most aggression among adult females is directed towards lower-ranking individuals, reinforcing rank.
- Females also direct significant aggression (42%) towards higher-ranking individuals.
- The presence of males decreases aggression towards higher-ranking females, while more females increase aggression towards lower-ranking ones.
- Lactating and pregnant females target higher-ranking individuals more often than cycling females, indicating a role for energetic needs.
Conclusions:
- Aggression heuristics in gorillas are context-dependent, influenced by social structure and reproductive state.
- These findings provide critical insights into the evolution of competitive behavior and decision-making in social animals.
- Aggression is not solely driven by rank reinforcement but is a flexible strategy adapted to varying ecological and social conditions.
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