The physical characteristics and usage patterns of stone axe and pounding hammers used by long‐tailed macaques in the Andaman Sea region of Thailand

Self Cite

Tool selection can affect the success of a tool-based feeding task, and thus tool-using animals should select appropriate tools when processing foods. We performed a field experiment on Piak Nam Yai Island in Laem Son National Park, Thailand, to test whether Burmese long-tailed macaques ( Macaca fascicularis aurea ) selected stone tools according to food type. We baited the island's shores with stone sets (‘tool tests’) in an effort to attract macaques to use stones presented in a quasi-experimental design. Tool tests were placed at 344 locations for 126 days over a 2 year period, with each set containing four stones of different mass (categories: X, 40–60 g; S, 90–100 g; M, 150–200 g; and L, 400–1000 g). Tool tests were checked when we could access them. The number of times each tool test was checked varied (1–32), for a total of 1950 checks. We also studied 375 non-experimental stone tools that were found at naturally occurring tool-use sites. Our data were not collected by direct observation, but by inspecting stones after use. We found an association between stone mass and food type. In the tool tests, we found S-stones were chosen most often for attached oysters, and L-stones were chosen most often for unattached foods. L-stones were almost always chosen for larger unattached foods (greater than 3 cm length), while for smaller unattached foods (less than or equal to 3 cm length) selection was less skewed to L-stones and more evenly distributed between the M- and L-stone categories. In the non-experimental study, we found that mass varied significantly across five food categories (range: 16–5166 g). We reveal more detail on macaque stone tool mass than previous studies, showing that macaques select differing stone masses across a variety of tool-processed foods. Our study is the first step in investigating the behavioural and cognitive mechanisms that macaques are using during tool selection.

Section: Discussionsupporting

confidence: 92%

Section: (B) Macaque Populationmentioning

confidence: 99%

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Long-tailed macaques select mass of stone tools according to food type

Gumert

Malaivijitnond

2013

Self Cite

“…Chimpanzees increased use of tools during periods of fruit scarcity at Bossou, Guinea [31]. Additional suggestions of tool use during times of necessity have been asserted for bearded capuchins in northeastern Brazil [45] and long-tailed macaques in Thailand [43], but the necessity hypothesis was not explicitly tested in these particular studies. There are also situations in which it is difficult to differentiate responses to necessity and opportunity.…”

Section: Introductionmentioning

confidence: 95%

Ecological and social correlates of chimpanzee tool use

Sanz

Morgan

2013

146

The emergence of technology has been suggested to coincide with scarcity of staple resources that led to innovations in the form of tool-assisted strategies to diversify or augment typical diets. We examined seasonal patterns of several types of tool use exhibited by a chimpanzee ( Pan troglodytes ) population residing in central Africa, to determine whether their technical skills provided access to fallback resources when preferred food items were scarce. Chimpanzees in the Goualougo Triangle exhibit a diverse repertoire of tool behaviours, many of which are exhibited throughout the year. Further, they have developed specific tool sets to overcome the issues of accessibility to particular food items. Our conclusion is that these chimpanzees use a sophisticated tool technology to cope with seasonal changes in relative food abundance and gain access to high-quality foods. Subgroup sizes were smaller in tool using contexts than other foraging contexts, suggesting that the size of the social group may not be as important in promoting complex tool traditions as the frequency and type of social interactions. Further, reports from other populations and species showed that tool use may occur more often in response to ecological opportunities and relative profitability of foraging techniques than scarcity of resources.

“…Most of these studies documented the use of tools only in a limited number of individuals and often the reports are anecdotal [6]. More recently, it has been reported that long-tailed macaques of a wild population in Thailand regularly use stones as tools to crack shelled seafood [7]. Despite this example, there is still a general agreement in the scientific community that macaques are not skilled tool users.…”

Section: Introductionmentioning

confidence: 99%

Individual and social learning processes involved in the acquisition and generalization of tool use in macaques

Macellini

Maranesi

Bonini

et al. 2012

Macaques can efficiently use several tools, but their capacity to discriminate the relevant physical features of a tool and the social factors contributing to their acquisition are still poorly explored. In a series of studies, we investigated macaques' ability to generalize the use of a stick as a tool to new objects having different physical features (study 1), or to new contexts, requiring them to adapt the previously learned motor strategy (study 2). We then assessed whether the observation of a skilled model might facilitate tool-use learning by naive observer monkeys (study 3). Results of study 1 and study 2 showed that monkeys trained to use a tool generalize this ability to tools of different shape and length, and learn to adapt their motor strategy to a new task. Study 3 demonstrated that observing a skilled model increases the observers' manipulations of a stick, thus facilitating the individual discovery of the relevant properties of this object as a tool. These findings support the view that in macaques, the motor system can be modified through tool use and that it has a limited capacity to adjust the learnt motor skills to a new context. Social factors, although important to facilitate the interaction with tools, are not crucial for tool-use learning.