Symbolic association between individuals and objects by a chimpanzee as an initiation of ownership

Rethinking the evolution of property and possession: A review and methodological proposition

Property is a key feature of modern human society; however, identifying the origin of this multifaceted behavior poses a formidable challenge. Here, we explore the methodologies for researching the origin of property. We discuss how an interdisciplinary approach can shed light on how our human ancestors shifted behaviorally from possessing an object to having exclusive property control over it. Possession occurs when social group members only respect an individual's claim to have exclusive access to an object when the individual has physical control over the object. Property occurs when an individual can claim exclusive access to an object, without challenge, regardless of whether the object is in their physical control or not. Researchers across different disciplines have asked what, if anything, distinguishes human property behavior from the behavior of other animals? Further, when and how did this behavior evolve in our lineage? Due to the considerable methodological challenges posed by researching this topic, few studies have been able to directly address these questions. In this review, we explore the challenges involved in defining property and possession and suggest a two-step approach to interdisciplinary definitions. Next, we evaluate four core approaches to the study of property behavior: evolutionary game theory, ethology, comparative cognition, and developmental psychology. Finally, we propose an empirical study, using an ethological approach to test the presence of property and possessive behavior in a natural setting, using our closest living relative, the chimpanzee (Pan troglodytes). Overall, we argue that this field of research is at a turning point, where the novel integration of various methods may provide an explanation to the origin of property.

Differentiated responses to different human conditions by chimpanzees

Chimpanzees' responses to human conditions were investigated. In the experimental condition, the experimenter pretended to injure the index finger, and in the control condition, the experimenter smiled and waved her hand to the chimpanzees. Although looking behavior was observed in both conditions, there was a difference in these types of behavior. Subjects seemed to concentrate their gaze on the experimenter's behavior in the experimental condition. The finding suggests the possibility that such different behaviors may be a basis for empathic behavior similar to that of human infants.