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The free‑ranging long‑tailed macaques at Bali’s Uluwatu Temple spontaneously barter stolen objects for food, providing an ecologically valid example of a culturally maintained token economy in non‑human primates.
The token exchange paradigm shows that monkeys and great apes are able to use objects as symbolic tools to request specific food rewards
Around the Uluwatu Temple in Bali, Indonesia, a large free-ranging population of long-tailed macaques spontaneously and routinely engage in token-mediated bartering interactions with humans. These interactions occur in two phases: after stealing inedible and more or less valuable objects from humans, the macaques appear to use them as tokens, by returning them to humans in exchange for food
The free‑ranging long‑tailed macaques at Bali’s Uluwatu Temple spontaneously barter stolen objects for food, providing an ecologically valid example of a culturally maintained token economy in non‑human primates.
Age influences success in both stealing and bartering, reflecting learned competence.
Monkeys adjust their acceptance of food rewards based on the value of the token they possess, demonstrating economic decision‑making.
The observed practice is cross‑generational, socially transmitted, and may represent a culturally maintained token economy.
The token exchange paradigm shows that monkeys and great apes are able to use objects as symbolic tools to request specific food rewards
Around the Uluwatu Temple in Bali, Indonesia, a large free-ranging population of long-tailed macaques spontaneously and routinely engage in token-mediated bartering interactions with humans. These interactions occur in two phases: after stealing inedible and more or less valuable objects from humans, the macaques appear to use them as tokens, by returning them to humans in exchange for food
The study aimed to develop a more ecologically valid primate model of trading systems that can inform our understanding of human economic behaviour.
Researchers combined field observations with experimental manipulations to document the two‑phase token‑mediated bartering process: macaques first stole inedible objects of varying value and then returned them to humans in exchange for food.
Field data revealed (i) age‑related differences in robbing and bartering success, indicating experiential learning, and (ii) strong behavioural links between the perceived value of tokens and the quantity or quality of food rewards that subadult and adult monkeys accepted or rejected, suggesting payoff maximisation.
The spontaneous token‑bartering behaviour of these macaques provides a naturalistic model of economic exchange, highlighting that complex trade‑like interactions can arise and be culturally sustained in free‑living animal societies.
The study is confined to a single macaque population at one temple site, limiting generalisability across species or habitats.
Observational and experimental data were gathered in a human‑altered environment, which may influence the naturalness of the behaviour.
Further research should compare token‑exchange behaviours across different primate groups and ecological contexts, and investigate the mechanisms of cultural transmission that sustain the token economy.
Understanding naturally occurring token economies in primates can inform models of human economic behaviour, aid in designing more ecologically valid experimental paradigms, and contribute to conservation strategies that consider human‑wildlife economic interactions.
The token exchange paradigm shows that monkeys
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