New evidence on the tool-assisted hunting exhibited by chimpanzees (Pan troglodytes verus) in a savannah habitat at Fongoli, Sénégal

Abstract

For anthropologists, meat eating by primates like chimpanzees (Pan troglodytes) warrants examination given the emphasis on hunting in human evolutionary history. As referential models, apes provide insight into the evolution of hominin hunting, given their phylogenetic relatedness and challenges reconstructing extinct hominin behaviour from palaeoanthropological evidence. Among chimpanzees, adult males are usually the main hunters, capturing vertebrate prey by hand. Savannah chimpanzees (P. t. verus) at Fongoli, Sénégal are the only known non-human population that systematically hunts vertebrate prey with tools, making them an important source for hypotheses of early hominin behaviour based on analogy. Here, we test the hypothesis that sex and age patterns in tool-assisted hunting (n=308 cases) at Fongoli occur and differ from chimpanzees elsewhere, and we compare tool-assisted hunting to the overall hunting pattern. Males accounted for 70% of all captures but hunted with tools less than expected based on their representation on hunting days. Females accounted for most tool-assisted hunting. We propose that social tolerance at Fongoli, along with the tool-assisted hunting method, permits individuals other than adult males to capture and retain control of prey, which is uncommon for chimpanzees. We assert that tool-assisted hunting could have similarly been important for early hominins.

Reproductive state and rank influence patterns of meat consumption in wild female chimpanzees (Pan troglodytes schweinfurthii)

“…Increased faunivory has been linked to distinct human life-history patterns in Homo relative to other apes (Finch and Stanford, 2004; Schuppli et al, 2012) and to the social organization of human ancestors, including provisioning, sexual division of labor, and a greater reliance on home bases (Isaac, 1978; Rose and Marshall, 1996; Kaplan et al, 2000; Bunn, 2009). Though there is growing evidence for butchery of large animals using stone tools prior to the emergence of the genus Homo (McPherron et al, 2010; Harmond et al 2015; Thompson et al 2015), this is likely to have been preceded by predation on smaller game at frequencies or in ways that may not be discernable in the fossil and archaeological records, and so resembles in some ways the hunting patterns of chimpanzees (Stanford, 1996; Pruetz et al, 2015). Extinct hominins’ access to high-quality, monopolizable food resources such as meat is likely to have been socially mediated, as is the case for chimpanzees, bonobos and human foragers.…”

Culture extends the scope of evolutionary biology in the great apes

“…Others have been reported since then, including sticks bitten and thus sometimes made sharp and used to stab or evict bush baby prey at Fongoli in Senegal (70,71); a kit of stout tools used to make tunnels; and fine stems used to fish down these tunnels and extract termites from nests deep underground (72). A majority of such tools are used in food extraction, but others are used in hygienic actions such as wiping blood or semen off fur, in protective comfort roles such as creating leaf-cushions on wet ground, and in local courtship gambits such as bending small shrubs on the ground (20,21).…”

Seasonal Variation in Physiology Challenges the Notion of Chimpanzees (Pan troglodytes verus) as a Forest-Adapted Species

“…These results contrast with the assumptions that savanna habitats offer fewer nutritional or energetic possibilities to the primates that inhabit them. Therefore, limitations stemming from lower arboreal density and diversity have been proposed to be restrictive to savanna chimpanzees, potentially necessitating alternative behavioral adaptations to accommodate reduction of opportunities (Kortlandt, 1983), such as tool-assisted hunting (Pruetz and Bertolani, 2007;Pruetz et al, 2015), party size variation (e.g., Wrangham, 1977;Wrangham et al, 1992;Chapman et al, 1995;Boesch, 1996;Matsumoto-Oda et al, 1998;Mitani et al, 2002;Hashimoto et al, 2003), and incorporation of fallback foods (Wrangham et al, 1991;Furuichi et al, 2001;Hernandez-Aguilar et al, 2007), including crop-raiding (Hockings et al, 2009).…”