Apes reciprocate food positively and negatively

Area of Science:

• Primate behavior
• Comparative psychology
• Evolution of cooperation

Background:

• Reciprocal food exchange is common in humans but rare in great apes, suggesting competition over food resources.
• Understanding ape-human food exchange differences is crucial for modeling the origins of human cooperation.

Purpose of the Study:

• To investigate the presence and conditions of in-kind food exchanges in great apes.
• To compare reciprocal food exchange behaviors between great apes and human children.

Main Methods:

• Experimental study involving chimpanzees and bonobos, with a comparison to 4-year-old human children.
• Replication of prior findings of no spontaneous food exchange in apes.
• Testing the effect of perceived intentionality on food-for-food and no-food-for-no-food exchanges.

Main Results:

• Great apes did not spontaneously exchange food.
• Positive reciprocal food exchanges (food-for-food) occurred at levels comparable to human children (75-80%) when intentionality was perceived.
• Great apes engaged in negative reciprocal exchanges (no-food for no-food) less frequently than children.

Conclusions:

• Reciprocal food exchange is possible in great apes under specific experimental conditions (perceived intentionality).
• Positive reciprocity may be a shared mechanism for fostering cooperation across species.
• Negative reciprocity, a stabilizing mechanism for cooperation, appears less developed in great apes compared to humans.