A Wild Chimpanzee’s Newly Invented Play Pattern towards an Artifact after a Short Exploration
Department of Sciences, Teikyo University of Science
Wild chimpanzees hold and manipulate various types of objects found in their habitat not only as tools, but also as objects to play with or to inspect (Ramsey & McGrew 2005; Nishida et al. 2010; Matsusaka et al. 2015). The shapes, weights, and other physical features of these target objects inevitably restrict the object manipulation patterns. Matsusaka et al. (2015) listed the diversity of object play among wild chimpanzees in Mahale, Tanzania. Infant or juvenile chimpanzees play with spherical objects or lumps, such as stones or fruits. These objects can be picked up, carried, raised and/or dropped, rotated with hands and/or feet laying supine on the ground, put on the chimpanzee’s back, held in the groin pocket, or thrown forward or backward under- or overarm. The chimpanzees also play with string-like objects, such as animal tails and skins, or vines, which they drag, drape, flail, and move, among others. Mahale chimpanzees handle not only natural objects, but occasionally, also human artifacts. It has been reported that when Mahale chimpanzees encounter artifacts such as an old abandoned native Tongwe clay pot, wooden boards, or plastic tags used for plant phenological research, they playfully dragged and carried them, or put these artifacts on their head. However, since only several cases are known of chimpanzees trying to steal human belongings throughout Mahale’s long research history (Matsusaka et al. 2015), chimpanzees are expected to have little idea how to handle the artifacts carried into the forest by the human observers. Intentional presentation or conferment of artifacts to wild chimpanzees should be avoided, because of the risk of disease transmission from humans to chimpanzees. Nonetheless, it is important to analyze how chimpanzees respond to artifacts they occasionally find in the forest, in order to manage such incidents when they happen by chance.
In this article, I report a case of how a juvenile wild chimpanzee in Mahale got hold of a digital video handycam (hereafter, camcorder) in the environment by chance, focusing on how the holder handled and manipulated the camcorder.
METHODS AND MATERIALS
Well-habituated wild chimpanzees of the M group in Mahale Mountains National Park, Tanzania, were studied from August to September 2014 (17 observation days and 86.6 observation hours in total) (see Nakamura et al. 2015 for details of the research site). The M group consisted of 63 members in the study period. The number and symbol in parentheses after each individual’s name represents his/her age and sex, respectively. I used a camcorder (SONY HDR CX430V: weight 420 g including a battery, size of the main body 58×66×128 mm, length of expanded grip belt 230 mm), a digital photo camera, and field notes to record the behavioral data.
On September 1, 2014, I started to follow an adult male CE (16♂). I started recording his behavior using the camcorder at 0905 h. A juvenile female QL (7♀), an infant female AY (4♀), a young male IH (11♂), an adult male DW (25♂), and CE were playing socially in turns, until 1058 h. CE moved into the wood, separating about 50 m away from the other members of the party. I started following CE, and put the camcorder in a pocket of my jacket at 1103 h. At 1125 h, I discovered I had unintentionally lost my camcorder, and in order to find it, I returned to our track.
Figure 1. QL handles the camcorder laying supine on the ground.
At 1126 h, I found QL handling the camcorder, lying supine on the ground beside the trail where I had observed CE at 1103 h (Figure 1). Since QL seemed eager to handle the camcorder, and frightening wild chimpanzees should be avoided, I decided not to disturb her. Instead, I decided to record her behavior with a digital photo camera or field notes, and to try to get the camcorder back after the chimpanzees would abandon it. QL continued biting, licking, and rotating the camcorder on her belly, then raised her upper body and moved forward on both hands after putting the camcorder in her groin pocket at 1130 h 20 s. QL threw the camcorder forward with her right underhand, and moved forward at 1130 h 35 s. QL then caught the camcorder, carried it, and laid supine on the ground at 1130 h 50 s, after which she was biting and licking the camcorder’s body. QL threw quadruped and rolled the camcorder forward at 1131 h 29 s, and subsequently moved to catch it. At 1131 h 39 s, QL lay supine again, licked and bit the camcorder. QL partially loosened the camcorder’s grip belt, which is meant for human users to put their hands in for holding the body of the camcorder at 1132 h 09 s, and continued to lick the belt and body of the camcorder. QL ran quadruped, biting the belt, at 1132 h 59 s, with the body of the camcorder dangling from her mouth. QL subsequently ran up a tree and chased AY and AY, who had escaped into the tree. At 1133 h 20 s, QL was hanging with both hands about 5 m above the ground from a branch of a tree. QL then loosened the belt from the camcorder’s body, whereas AY was hanging 3 m away from her. QL started kicking the body of the camcorder, alternating both soles, and dangling it by biting one end of the camcorder’s belt at 1133 h 33 s (Figure 2; see also video 1 by photo camera, available online at https://www.youtube.com/watch?v=Wkz_k9aJ288). QL kicked the camcorder’s body ten times by right sole, and eight times by left sole for 6 s and the camcorder fell to the ground at 1133 h 42 s, and QL immediately ran down from the tree and picked it up. She then ran into the bushes, and up another tree. While QL was hanging down from the tree by one hand, she dangled the main body of the camcorder from her mouth by biting the belt, and consequently starting kicking the body by alternating both soles again. At 1135 h 30 s, QL threw the camcorder down from a tree, from about 3 m above the ground. Since QL did not move rapidly towards the camcorder, I managed to retrieve it.
Figure 2. QL kicks the body of the camcorder on right foot (A) and on left foot (B), biting one end of the grip belt of the camcorder to dangle it, while she hangs from a tree (image captured from footage by photo camera).
Throughout the observation, QL did not display a play face and did not utter play pants, nor did she handle the camcorder imitating normal usage by humans, such as holding camcorder by grip belt, opening LCD monitor, or looking into lens. In addition, other chimpanzees, including AY who was at a visual distance from QL, paid no attention to QL or the camcorder. Fortunately, the camcorder’s body or the internal data were not destroyed except for a part of built-in cable.
The camcorder might have immediately slipped out of the pocket of my clothes after I started following CE, since QL was found handling it at the same place where I had observed CE. Although it is still unknown when QL acquired the camcorder exactly, she handled the camcorder for at least 9 min. During the handling, QL showed continuous biting or licking of both the body and belt of the camcorder. These patterns can be considered non-playful manipulation or exploration (Ramsey & McGrew 2005). Juvenile chimpanzees that encounter a novel object are considered to try to inspect its physical features, such as the hardness, weight, or shape. After QL inspected the camcorder for several minutes, she threw it forward and transported it. During these actions, QL discovered that the belt could be expanded, and she repeatedly loosened it. The former is suggested to be the behavioral pattern of solo object play toward sphere-like objects, and the latter is that toward string-like objects (Matsusaka et al. 2015). As soon as QL succeeded to fully expand the belt, she started kicking the camcorder, which was then hanging down from her own mouth. The motor pattern ‘kicking object’ is partially equal to ‘hang with legs pitterpat’ used to respond to a play partner in a tree, or to ‘rotate fruit’, carried out lying supine on the ground for object play (Nishida et al. 2010). It is therefore implied that QL engaged in kicking the camcorder as object play.
Although captive chimpanzees show various motor patterns responding to the shapes of artifacts and their combinations (Ramsey & McGrew 2005), wild chimpanzees in Mahale are unlikely to find artifacts like the camcorder. Likewise, they are unlikely to find detached natural objects that physically combine a handful lump and string shape during their daily activities. Possible exception may be a set of a handful-sized fruit of ikolyoko (Voacanga africana) and the peduncle, which chimpanzees would encounter in a certain season of the year, and thus it cannot be denied that chimpanzees may play with them. Few researchers, however, have reported the play of Mahale chimpanzees with such the sets of the objects (Nishida et al. 2010; Matsusaka et al. 2015; Hosaka pers. com., Shimada unpublished data). QL’s play behavior toward the camcorder is therefore not ordinary among wild chimpanzees, but a novel motor pattern that she invented by adapting her play to the lump (the camcorder’s body) and string (the belt) combination. This observation suggests that the creative, cognitive, and physical ability of wild chimpanzees can combine two different established behavioral patterns, and modify them into a new motor pattern after intensive inspection of the novel artifact for several minutes.
I would like to thank COSTECH, TANAPA, TAWIRI, MMNP, and MMWRC for permission to conduct research in Mahale. This study was funded by a MEXT Grant-in-Aid (KAKENHI) (#26284138).
Matsusaka T, Shimada M, Nakamura M 2015. Diversity of play. In: Mahale Chimpanzees: 50 Years of Research. Nakamura M, Hosaka K, Itoh N, Zamma K (eds), Cambridge University Press, Cambridge, pp. 544–555.
Nakamura M, Hosaka K, Itoh N, Zamma K (eds) 2015. Mahale Chimpanzees: 50 Years of Research. Cambridge University Press, Cambridge.
Nishida T, Zamma K, Matsusaka T, Inaba A, McGrew WC 2010. Chimpanzee Behavior in the Wild: An Audio-Visual Encyclopedia. Springer, Tokyo.
Ramsey JK, McGrew WC 2005. Object play in great apes. Studies in nature and captivity. In: The Nature of Play. Pellegrini AD, Smith PK, (eds), The Guilford Press, New York, pp. 89–112.
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