The art of chimpanzee (Pan troglodytes) diplomacy: Unraveling the secrets of successful negotiations using machine learning.

Social negotiation is crucial in human interactions and often involves clear communication, strong socialization skills, adept problem-solving abilities, and strategic planning. Chimpanzees exhibit evidence of social negotiation through manual gesturing to achieve imperative goals. Chimpanzee social negotiations are influenced by demographic factors like age, sex, social rank, and identity, as well as communicative properties such as gesture type, gesture modality, gesture position, and context. In our study, we build on prior research by analyzing how chimpanzees use facial signals during social negotiations. We used machine learning models and sequential pattern analysis to analyze the combined effects of facial signals and manual gesturing properties, along with demographic factors. Our analyses revealed that facial signals and manual gesturing are important for predicting the success of chimpanzee social negotiations. We also found that clear communication (using distinct facial signals and manual gestures in each context) is important for navigating social negotiations, much like is true for humans. Our research showcases the immense value of machine learning techniques in exploring the evolution of social behavior in primates. (PsycInfo Database Record (c) 2025 APA, all rights reserved).