Unenculturated chimpanzees fail to produce & use sharp stone tools in the absence of know-how demonstrations
MOST of these SLIDES IS BY: Elisa Bandini
Claudio Tennie Elisa Bandini, Alba Motes- Rodrigo, William Archer, Tanya Minchin, Helene Axelsen, Raquel Adriana Hernandez-Aguilar,
Shannon P. McPherron 1 Early Stone Tools (EST)
• Earliest tools found in the hominin record – Secure case: Oldowan (approx. 2.58Ma1)
• These were “sharp stone tools” (~artificial teeth)
1. Braun et al., (2019; PNAS) 2 How was the neccessary know-how derived?
• My lab’s question: Was the know-how copied?
• Can look at patterns across time, space and species
– Lack of evidence for know-how copying 1,2
• Can test for spontaneous, individual know-how reinnovation
– No tests of hominins lacking a time machine – But, non-human great apes can be tested today 3
• cognitive inferenes regarding LCA
1. Tennie et al. (2016) 2. Tennie et al. (2017) 3. e.g. Marchant and McGrew (2005 in Stone Knapping)3 Indeed, apes have been tested
• 1 Orangutan: Abang1
• 2 Bonobos: Kanzi & Panbanisha2
• Subjects given puzzle box and materials to make sharp stone tools
1. Wright (1972, Mankind) 2. Toth et al. (1993, J. Archeol. Sci.); 4 youtube.com/watch?v=3exAOxSKYCE Good studies, but there are two problems – enculturation and non-naivety • 1) Human enculturation renders apes unrepresentative for LCA
– Kanzi and Panbanisha very enculturated – Abang’s enculturation status: possible • 2) Human demonstrations were provided to all subjects prior to test 1,2
– Abang’s actions were even moulded
5 1. Wright (1972, Mankind) 2. Toth et al. (1993, J. Archeol. Sci.) To target LCA, one must test unenculturated, naive apes
– No humans were present that enculturated LCA or early hominins
– No humans were present that demonstrated/moulded the underlying know-how
6 And so, we tested unenculturated, naive apes • We tested chimpanzees 1
– Most extensive ape tool-use repertoire in the wild
– Have been observed to unintentionally make sharp stones whilst nut-cracking 2
Can naive, unenculturated chimpanzees spontaneously and individually make and use sharp stone tools?
7 1. Pradhan et al., (2012; JHE) 2. Carvalho et al., (2008; J Hum Evol) The sample
• Total N=11
• Chimfunshi wildlife orphanage, Zambia & Dyreparken zoo, Norway
8 Methods largely followed earlier studies
• Provided two baited puzzle boxes that could only be accessed with sharp stone tools
– “Hide-box” and “Tendon-box”
9 Raw material for sharp stone tools • Stone core w. suitable angles
• Round hammerstones
10 Production & usage test conditions
• 1st: Production condition: – Raw materials plus puzzle boxes only Test whether chimpanzees would spontaneously produce a sharp stone tool
• 2nd: Usage condition: – Raw materials plus puzzle boxes plus a sharp stone tool Test whether chimpanzees would spontaneously use a sharp stone tool 11 Hindight is 20/20, thus...
• Prior to telling them, I recently asked at a major US archaeology department what outcome they predicted
– No clear main answer emerged – Indeed, answers covered a wide range (from “many” to “none”)
Prior to our study we simply were unable to predict what would happen
12 Results • Unsurprisingly, subjects were motivated to manipulate the puzzle boxes and raw material
13 Results 1
• Yet, none of the 11 naive, (and likely) unenculturated chimpanzees .... • ....made or used sharp stones in any of these two test conditions 1
1. Bandini, Motes-Rodrigo et al., (2021; Open Research Europe, under review) 14 MS is available, but under review (e.g. here: tinyurl.com/chimpstonetools)
15 Summary • All earlier studies tested non-naïve apes – who were also often (always?) enculturated
• These studies were good & important – but they did not address skills of LCA
• To do that,
– .... Naive, unenculturated apes must be tested
• We did this, and chimpanzees failed
16 Discussion
• Enculturation and/or human demonstrations may be necessary before apes (chimpanzees) produce and/or use sharp stone tools
17 Still, sharp stone tools need not be rocket science
• Naïve, unenculturated captive capuchins have also been tested (same N=11)1
Capuchins made and used sharp stone tools 1
• Proof of principle that sharp stone tools need not require know- how copying
• Thus, our question remains open
18 1. Westergaard & Suomi (1994, J. Hum. Evol) Acknowledgments
• ERC for funding the STONECULT project • All co-authors – in particular EB and ABM • Chimfunshi Wildlife Orphanage Trust and Kristiansand Zoo • L. Kristensen, A. Coombes & R. Mundry
@CTennie
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