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Kokolopori Bonobos

An agent-based model of bonobo social structure at the Kokolopori Bonobo Reserve in the Democratic Republic of Congo. Four neighbouring social groups — Ekalakala, Kokoalongo, Fekako, and Bekako — share overlapping home ranges in the equatorial forest.

Movement

Each agent moves within its group’s range under three forces:

• A correlated random walk with a mild pull back toward the group’s home-range centroid.
• Vocal cohesion with clustermates within ~700 m of audible range — long-distance calls keep group members loosely aggregated.
• Inter-group coupling at a longer ~2 km mid-range: each agent is mildly drawn toward the nearest out-group neighbour. This positive coupling is the tolerance signal that distinguishes bonobos from more territorial relatives. Setting the coupling negative would model avoidance instead.

Parties and the social currencies

Agents within close proximity form a party. Five kinds of social currency are tracked between party members and rendered as coloured lines on the map:

• SRI association — how often two individuals are in the same party.
• Grooming — directed grooming events.
• Coalition — joint coalitions formed within a party.
• Food sharing — directed food-sharing events (fruit, meat, honey, mushrooms).
• Aggression — directed aggressive encounters.

Toggle the currencies on and off independently to see how the cluster boundary shapes — or doesn’t shape — each kind of relationship. Currency edges decay over time on a reciprocity-memory timescale; SRI accumulates without decay.

Decision interface for mixed parties

When a party contains members from more than one group, every member runs a join policy that decides whether to participate in this mixed encounter. The default always policy accepts every offer (the baseline); the included threshold policy admits only individuals whose cooperative disposition exceeds a fixed level. Custom policies (reinforcement-learning, Bayesian belief updating, threshold heuristics) can plug into the same interface and condition on context. Each decision is logged and visible per-agent in the dossier.

Click any bonobo

Click a glyph on the map to open a floating dossier: the individual’s name, sex, group, cooperative disposition, top recent partners across every currency, and their last few join/avoid decisions. The dossier updates live as the simulation advances.

Sociogram view

Switch the right pane from Map to Sociogram to see every checked network as a force-directed graph in a shared layout, with nodes coloured by group. Edges keep their currency colour so the union of currencies is comparable in one frame.

Mixed-encounter time series

The sidebar chart tracks how many mixed-group parties exist at each moment versus the total number of multi-member parties. This is the central observable: the rate and dynamics of cross-group encounters as they emerge from the underlying movement and decision rules.

Time controls

Play, pause, single-step, or change the speed. The scrubber lets you jump anywhere in the simulated timeline; because the model is deterministic, scrubbing backward re-derives the history exactly. Each model tick is 30 simulated minutes.