Publication details
Acquisition of object-robbing and object/food-bartering behaviours: a culturally maintained token economy in free-ranging long-tailed macaques
2021

Jean‐Baptiste Leca; Noëlle Gunst; Matthew Gardiner, and others

2021
Headline

The study examines the token exchange paradigm in a population of long-tailed macaques in Bali, Indonesia, providing insights into the cognitive underpinnings of economic behaviour in non-human primates, and suggests that this population may be the first example of a culturally maintained token economy in free-ranging animals.

Highlights

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

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Snapshot

The study examines the token exchange paradigm in a population of long-tailed macaques in Bali, Indonesia, providing insights into the cognitive underpinnings of economic behaviour in non-human primates, and suggests that this population may be the first example of a culturally maintained token economy in free-ranging animals.

Key findings

The key findings of the study include age differences in robbing/bartering success, indicative of experiential learning, and clear behavioural associations between value-based token possession and quantity or quality of food rewards rejected and accepted by subadult and adult monkeys.

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

Objectives

The objective of the study is to provide a more ecologically valid primate model of trading systems in humans by examining the token exchange paradigm in a free-ranging population of long-tailed macaques.

Methods

The study uses field observational and experimental data to examine the token-mediated bartering interactions between the long-tailed macaques and humans.

Results

The results of the study show that the long-tailed macaques are able to use objects as symbolic tools to request specific food rewards, and that there are age differences in robbing/bartering success and clear behavioural associations between value-based token possession and food rewards.

Conclusions

The study concludes that the population of long-tailed macaques in Bali, Indonesia, may be the first example of a culturally maintained token economy in free-ranging animals, and that this population provides insights into the cognitive underpinnings of economic behaviour in non-human primates.

Key terms

token economy

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Limitations

The study does not explicitly mention any limitations, but it notes that laboratory-based experimental situations tend to have limited ecological validity.

Future work

The study does not explicitly mention any future work, but it is part of a theme issue on the existence and prevalence of economic behaviours among non-human primates, suggesting that further research in this area is needed.

Practical applications

The study has practical applications for understanding the cognitive underpinnings of economic behaviour in non-human primates, and for developing more ecologically valid models of trading systems in humans.

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Important points

The token exchange paradigm shows that monkeys

These interactions occur in two phases

the macaques appear to use them as tokens

Key concepts
Abstract
The token exchange paradigm shows that monkeys and great apes are able to use objects as symbolic tools to request specific food rewards. Such studies provide insights into the cognitive underpinnings of economic behaviour in non-human primates. However, the ecological validity of these laboratory-based experimental situations tends to be limited. Our field research aims to address the need for a more ecologically valid primate model of trading systems in humans. 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. Our field observational and experimental data showed (i) age differences in robbing/bartering success, indicative of experiential learning, and (ii) clear behavioural associations between value-based token possession and quantity or quality of food rewards rejected and accepted by subadult and adult monkeys, suggestive of robbing/bartering payoff maximization and economic decision-making. This population-specific, prevalent, cross-generational, learned and socially influenced practice may be the first example of a culturally maintained token economy in free-ranging animals. This article is part of the theme issue ‘Existence and prevalence of economic behaviours among non-human primates'.
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References
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