Ethoarchaeology and Elementary Technology of Unhabituated Wild Chimpanzees at Assirik, Senegal, West Africa

Like other wild chimpanzees (Pan troglodytes), the savanna-dwelling apes of Assirik, Senegal, West Africa, make and use tools and so have an elementary technology. Unlike their more famous counterparts elsewhere in Africa, these apes are not observable at close range. Instead, they are amenable to etho-archaeological study, in which the indirect data of artifacts, remnants, and fecal contents add to the sparse behavioral data. These open-country hominoids show 15 behavioral patterns that appear to be material culture, in the minimal sense of socially learned behavioral diversity. These can be divided into subsistence (N = 7), social (5) and maintenance (3) activities shown at customary, habitual, or present levels of frequency. Some patterns, such as Termite Fish or Baobab Crack, leave behind assemblages of hundreds of artifacts or remnants in predictable contexts at enduring worksites. Other patterns are rare and ephemeral and are known only from anecdotal data. Almost all artifacts and remnants are non-lithic, and so their perishability limits their discovery and analysis. Maximally productive use of such data depends on close collaboration between archaeology and primatology. PaleoAnthropology 2003.05. 02.1–20 Copyright © 2003 PaleoAnthropology Society. All rights reserved. 2 • P a l e o A n t h r o p o l o g y 2 0 0 3 I N T R O D U C T I O N Observers of unhabituated wild chimpanzees and paleoanthropologists face a similar problem: They have artifacts but little or no behavioral data on their use. The aims of this paper are to: Describe comprehensively for the first time the elementary technology of an unhabituated population of wild chimpanzees, analyze these mostly indirect data based mostly on artifacts and other remnants, situtate the Assirik findings in the species-typical context of Pan troglodytes, and explore how students of prehistory and primatology might help one another. Habituation is the process of reducing wild animals’ fear of human beings in order to make them accessible to behavioral observation. It can be done in various ways, the best of which is repeated neutral exposure to humans, so that the subjects’ wariness declines. Fully habituated subjects can be watched at closerange throughout their active periods. Of the 40–plus sites at which wild chimpanzees have been studied, only a handful (e.g. Gombe, Goodall, 1986) have achieved full habituation. The others yield only indirect, non-observational data or fragmented, intermittent observations to varying extents (e.g. Tutin et al., 1995; Matsuzawa & Yamakoshi, 1996). Therefore, primatologists at most sites must draw inferences about behavior based on circumstantial evidence. All primates leave behind indirect evidence of their presence, and even of their characteristics and activities, that are comparable to data collected on humans by archaeologists: hair (Bonnichsen et al., 2001), feeding remains (Hardy et al., 1997), DNA (Matheson & Loy, 2001), tracks (Leakey & Hay, 1979), bones (Selvaggio & Wilder, 2001), feces (Hunt et al., 2001), foraging signs (Prince, 2001), shelter (Sommer, 1999), etc. Most of this evidence is non-lithic and is not from artifacts. In recent years, findings from field studies of chimpanzees have informed directly the interpretation of archaeological discoveries: Sept. (1992, 1998) pioneered analogical analysis of chimpanzee nest-building and hominid home-ranging. Backwell and d’Errico (2001) used knowledge of chimpanzee termite-eating to reanalyse bone digging tools used by australopithecines. Goren-Inbar et al. (2002) referred to chimpanzee nut-cracking in order to model the origins of pitted stones as hammers and anvils used by Middle Pleistocene hominids. Finally, Mercader et al. (2002) went a step further in excavating the lithic technology of West African chimpanzees, at nut-cracking work-sites. Among living nonhuman species, only the chimpanzee (Pan troglodytes) typically makes and uses a tool-kit in daily life (McGrew, 1992). First described by Goodall (1964), such elementary technology has been recorded across populations in east, central and west Africa. Variation in artifacts across populations ranges from environmentally to culturally determined (McGrew et al., 1997). Most of the well-known findings come from forest or forest-woodland mosaic sites where the apes are fully habituated, e.g. termite fishing at Gombe (Goodall, 1986) or nut cracking at Tai (Boesch & Boesch, 1990). E L E M E N TA R Y T E C H N O L O G Y O F W I L D C H I M PA N Z E E S • 3 Recent cross-cultural analyses of these few well-known populations have produced an inclusive framework for systematic comparison (Whiten et al., 1999, 2001). Some of these artifacts cannot now be distinguished as ape or early hominid based on appearance alone, e.g. use-wear patterns on stone anvils (Joulian, 1996, Goren-Inbar et al., 2002). Here, we report for the first time the comprehensive technology of a savannaliving and unhabituated community of wild chimpanzees at Assirik, Senegal.