Primate archaeology

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: Introductionmentioning

confidence: 99%

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

Gumert

Malaivijitnond

2013

“…These data are likely skewed by research effort and observation effects, which is why captivity bias must remain a speculative suggestion at present rather than a firm principle, and similar data from other tool using taxa are required. Nevertheless, the species that are currently most often compared with hominins (including all the primates that use stone tools in the wild today) [15] have long histories of study both in the wild and captivity, with specific attention paid to their tool use [16,17 -22]. Other primate species that are considered essentially non-tool-users in nature have also been shown to be capable of tool use under captive conditions, including Japanese macaques [23], baboons [3], cotton-top tamarins and vervet monkeys [24].…”

Section: 'Captivity Bias' In Animal Tool Use (A) Animal Tool Use In Cmentioning

confidence: 99%

‘Captivity bias’ in animal tool use and its implications for the evolution of hominin technology

Haslam

2013

Self Cite

Animals in captive or laboratory settings may outperform wild animals of the same species in both frequency and diversity of tool use, a phenomenon here termed ‘captivity bias’. Although speculative at this stage, a logical conclusion from this concept is that animals whose tool-use behaviour is observed solely under natural conditions may be judged cognitively or physically inferior than if they had also been tested or observed under controlled captive conditions. In turn, this situation creates a potential problem for studies of the behaviour of extinct members of the human family tree—the hominins—as hominin cognitive abilities are often judged on material evidence of tool-use behaviour left in the archaeological record. In this review, potential factors contributing to captivity bias in primates (including increased contact between individuals engaged in tool use, guidance or shaping of tool-use behaviour by other tool-users and increased free time and energy) are identified and assessed for their possible effects on the behaviour of the Late Pleistocene hominin Homo floresiensis . The captivity bias concept provides one way to uncouple hominin tool use from cognition, by considering hominins as subject to the same adaptive influences as other tool-using animals.

“…The earliest evidence of stone tool use consists of cut marks on animal bones dated to 3.4 million years (Myr) ago [1]. However, discoveries of past tool technology are both biased and limited by artefact preservation [2]. All living apes use tools, and common chimpanzees (Pan troglodytes) and orangutans (Pongo spp.)…”

Section: Introductionmentioning

confidence: 99%

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.