Abstract
Habitual reliance on tool use is a marked behavioural difference between wild robust (genus Sapajus) and gracile (genus Cebus) capuchin monkeys. Despite being well studied and having a rich repertoire of social and extractive foraging traditions, Cebus sp. rarely use tools and have never been observed using stone tools. By contrast, habitual tool use by Sapajus is widespread. We review theory and discuss factors which might explain these differences in patterns of tool use between Cebus and Sapajus. We then report the first case of habitual stone tool use in a gracile capuchin: a population of white-faced capuchins (Cebus capucinus imitator) in Coiba National Park, Panama who habitually rely on hammerstone and anvil tool use to access structurally protected food items in coastal areas including Terminalia catappa seeds, hermit crabs, marine snails, terrestrial crabs and other items. This behaviour has persisted on one island in Coiba National Park since at least 2004. From 1 year of camera trapping, we found that stone tool use is strongly male-biased. Of the 205 camera trap days where tool use was recorded, adult females were never observed to use stone tools, although they were frequently recorded at the sites and engaged in scrounging behaviour. Stone tool use occurs year-round in this population; over half of all identifiable individuals were observed participating. At the most active tool use site, 83.2% of days where capuchins were sighted corresponded with tool use. Capuchins inhabiting the Coiba archipelago are highly terrestrial, under decreased predation pressure and potentially experience resource limitation compared to mainland populations—three conditions considered important for the evolution of stone tool use. White-faced capuchin tool use in Coiba National Park thus offers unique opportunities to explore the ecological drivers and evolutionary underpinnings of stone tool use in a comparative within- and between-species context.
Highlights
Extractive foraging permits many generalist species to access structurally protected resources
We report the first case of habitual stone tool use in a gracile capuchin: a population of whitefaced capuchins (Cebus capucinus imitator) in Coiba National Park, Panama who habitually rely on hammerstone and anvil tool use to access structurally protected food items in coastal areas including Terminalia catappa seeds, hermit crabs, marine snails, terrestrial crabs and other items
From 1 year of camera trapping, we found that stone tool use is strongly male-biased
Summary
Extractive foraging permits many generalist species to access structurally protected resources. It requires both physiological specializations and/or cognitive traits that aid in resource manipulation and extraction. It is important to the ecological success and evolutionary history of many primates. Comparative studies of tool use are key to understanding the ecological and social factors that drive its evolution within the primate lineage. The cognitive skills required for tool use was probably selected for alongside social and ecological intelligence [4] and generalized problemsolving [5] (but see [6] for exceptions to this in other taxa). Once tool use evolves it may create interesting eco-evolutionary feedbacks via gene-culture coevolution and/or cultural niche construction that are probably important in hominin evolution [7,8,9]. The cultural transmission of toolkits and associated behaviours is of central importance to human evolution; it is key to our success as the most widely dispersed vertebrate on Earth
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