Wild monkeys flake stone tools

Abstract

* These authors contributed equally to this work. Paleoanthropologists use the distinctive characteristics of flaked stone tools both to distinguish them from naturally broken stones, and to interpret the behaviour of the hominins that produced them 4 . Suggested hallmarks of the earliest stone tool technology include (i) controlled, conchoidal flaking 5 , (ii) production of sharp cutting edges 6 , (iii) repeated removal of multiple flakes from a single core, (iv) clear targeting of core edges, and (v) adoption of specific flaking patterns 7 . These characteristics underlie the identification of intentional stone flaking at all early archaeological sites 3,5,[7][8][9][10][11][12] , as they do not co-occur under natural geological conditions. To date, comparisons between hominin intentional stone flaking and wild primate stone tool use have focused on West African chimpanzees (Pan troglodytes verus) [13][14][15][16] . Nevertheless, stone breakage during chimpanzee tool use is accidental 15 , a result of missed hits or indirect force application during activities such as nut-cracking. The resulting stone fragments lack most of the diagnostic criteria listed above for hominin flakes 10,17 . Even when the manufacture of sharp edges was taught to captive bonobos (Pan paniscus), the resulting flaked assemblage did not replicate the early hominin archaeological record 18 .The capuchins of Serra da Capivara National Park (SCNP) in Brazil use stone tools in more varied activities than any other known non-human primate, including for pounding foods, digging, and in sexual displays [19][20][21] . Bearded capuchins and some Japanese macaques (Macaca fuscata) are known to pound stones directly against each other 22 , however, the SCNP capuchins are the only wild primates that do so for the purpose of damaging those stones 19 . This activity, which we term stone on stone (SoS) percussion, typically involves an individual selecting rounded quartzite cobbles from a conglomerate bed (active hammers), and with one or two hands striking the hammerstone forcefully and repeatedly on quartzite In addition to deliberately crushing the surface of both the active and passive hammers, the capuchins regularly unintentionally break the stones during use (Extended Data 1). In addition, we observed a capuchin purposefully place a newly fractured stone flake on top of another stone, and then strike it with a hammer in a manner resembling chimpanzee nutcracking or human bipolar reduction (Extended Data 1). Nevertheless, while the monkeys were seen to re-use broken hammerstone parts as fresh hammers, they were not observed using the sharp edges of fractured tools to cut or scrape other objects.We collected fragmented stones immediately after capuchins were observed using them at the Oitenta site in SCNP (8º 52.394 S, 42º 37.971 W) (Figure 1), as well as from surface surveys and archaeological excavation in the same area (Extended Data 2). The assemblage consists of 111 capuchin modified stone artefacts, including complete and broken hammerst...

Nut Cracking Tools Used by Captive Chimpanzees (Pan troglodytes) and Their Comparison with Early Stone Age Percussive Artefacts from Olduvai Gorge

“…However, it seems that between a pounding-like activity such as nut cracking and an intentional flaking activity there is an ‘intermediate step’, a stage in which the evolution of certain aspects related to the cognitive capabilities of hominins would have played an important role, and in which hominins would have acquired the skills necessary to systematically knap stone tools [2, 39]. However, this stage would be difficult to recognize in the fossil record because of the lack of archaeologically visible remains (but see Proffitt et al, [81]).…”

Habitual stone-tool-aided extractive foraging in white-faced capuchins,Cebus capucinus

“…Percussive techniques like those observed in non-human primates may have been the precursor to the earliest hominin stone tool making around 3 Ma [10–14]. Thus, a better understanding of tool use in non-human primates helps us to validate and critically evaluate our interpretations of the fossil and archaeological records [15]. Further, comparative studies of tool use in extant primates allow us to better interpret and understand what early lithic technologies looked like, how they may have been used by ancient hominins, as well as how site preservation and visibility (e.g.…”

Capuchin monkeys can make and use stone tools

“…Proffitt, Luncz, Falótico, Ottoni, de la Torre, and Haslam (2016) recently reported in Nature that wild capuchin monkeys unintentionally produce sharp stone flakes, but they do not purposefully use these flakes for cutting. In an associated opinion piece, the Editors of Nature downplayed any connection between these findings and the development of human stone tool production and use.…”

“…Specifically, Proffitt et al (2016) reported that wild bearded capuchin monkeys (Sapajus libidinosus) in Brazil “deliberately break stones unintentionally producing … sharp-edged flakes and cores that have the characteristics and morphology of intentionally produced hominin tools chipped from larger rock cores” (p. 85, italics added). Stone breaking by capuchins is not remarkable in and of itself.…”