Tool use in Singaporean monkeys

18Apr09

Read an interesting paper yesterday by Chiang (1967) about macaques (Macaca fascicularis) at the Singapore Botanic Gardens using tools. He observed them using leaves to wipe food before eating it. There were also a few instances of them ‘leaf-washing a toad that exuded defensive slime, the latter of which they didn’t end up eating.

The most widely-publicised parallel is found in seaside-living Japanese macaques (Macaca fuscata), which taught themselves how to wash sweet potatoes before eating them. But those were provisioned by Japanese researchers; the Singapore population was observed doing so by a researcher who happened to notice them while attempting to survey their breeding behaviour on regular walks. However, it’s unclear whether or not they were provisioned by the public at the time of observation.

Tool use is a major field in primatology, not least because many such examples are confined to specific populations. Even when one takes ecological factors (i.e. a certain food that can be extracted using tools is present in only one population, but not another), one finds enough variation to reliably justify the hypothesis that non-human primates have their own, population-specific, socially transmitted ‘culture’.

Indeed, Chiang (1967) stated that, as similar leaf wiping behaviour had not been observed in other Singaporean or Malaysian populations at the time, it was possible that the ‘leaf-washing’ reflected a unique ’sub-culture’ in the Singapore Botanic Gardens macaques.

The paper was published in Nature - a major scientific journal – in 1967. Due to public complaints, the entire Singapore Botanic Gardens population was eradicated by NParks in the 1970s. It is heartbreaking how much we take our biodiversity for granted.

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