<Article> Innovative Behavior at Mahale: New Data on Nasal Probe and Nipple Press.

Abstract

For more than three decades, observers of wild chimpanzee unit groups (communities) have noted behavioral patterns that lend support to the idea of inter-populational differences in behavior that cannot be explained by ecological variables. McGrew & Tutin (1) suggested that the grooming hand clasp, as practiced by the chimpanzees of the Mahale Mountains, Tanzania, can be recognized as a custom. Nishida (2) documented the leaf-clipping display and discussed mechanisms of transmission (3). 1990s have yielded important syntheses of these differences as reflected in material culture, e.g., use (4). Boesch and Tomasello (5) reviewed population-specific behavioral patterns for six long-term research sites and addressed the cognitive and learning mechanisms that may underlie the acquisition of such behavioral patterns. Whiten et al. (6) summarized 65 categories of use and social acts from the seven most long-term sites. Thirty-nine of these patterns were found to be cultural patterns of behavior that are transmitted repeatedly through social acts to become a population-level characteristic (3). McGrew & Marchant (7) assessed the robustness of phenomena that are potentially cultural. They suggested four degrees of data: anecdotal unique or rare events; idiosyncratic events exhibited by only one individual, however often; habitual events repeated by several individuals; and customaryregular events by all appropriate individuals. Nishida (8) reviewed new findings on Mahale chimpanzees. In a section entitled Innovative behaviors and culture (pp. 382-84) he reported some idiosyncratic behavioral patterns. Here we present further observations on nasal probe and press. Nasal probe entails using a toothpick-like tool to induce sneezing that clears the nasal passage (9). It was shown four times by an adult male, Kalunde, during a flu-like illness in fall 1992. He inserted the deeply into one of his nostrils, which often immediately stimulated him to sneeze. When he sneezed, a large amount of nasal mucus was discharged onto his upper lip. mucus was then picked off and quickly ingested. (p. 219) In Sept.-Dec.1996, we studied laterality of function (hand preference) of M group, using an ethogram with 38 behavioral patterns and focal animal sampling. On 8 Oct., LFM saw Maggy, a 9-year-old adolescent, hold a small twig in her left hand to probe her left nostril. She also used her left index finger to probe her left nostril. This bout of nasal probing produced mucus that she ate; she then put the twig cross-wise in her mouth. Soon after, she repeated the procedure and succeeded in inducing a sneeze that yielded more mucus. She ate this second discharge of mucus with some leaves. No further observations of nasal probe by Maggie or any other M group chimpanzee were made by us in that field season. Nipple press, was described by Nishida as: The adolescent male Alofu began habitually pressing his fingers on his nipples when pant-grunting to adult males, apparently showing them his extreme respect (p. 382) (8). In a later publication (10) Nishida noted that Alofu regularly stimulates his nipples when scared by mature (p. 383) and that three prime adult females, (Fatuma, Wakilufya, and Wakusi) occasionally touched or stimulated their nipples. In their 1999 ethogram of the Mahale chimpanzees, Nishida et al. (11) catalogued this pattern as fumble with nipple (p. 155) and suggested a self-reassurance or self-stimulation function for the pattern. During fall 1996, four individuals engaged in press, but the pattern continued to be displayed most often by Alofu, who by then, was a 14-year-old adult male (see Table 1). Typically, the pattern was one-handed (91 bouts were recorded) but three instances were bimanual. other 3 individuals who pressed were: Abi, a 14-year-old female; Gwekulo, a 34-year-old adult female; and Ikocha, a 31-year-old adult female. Of the adult females who were reported on earlier (10), Fatuma and Wakusi were still members of M group but were not seen to press; Wakilufya had died. This pattern has been maintained by Alofu, who also has elaborated and generalized the pattern. Now, Alofu rarely pant-grunted while pressing, even when in the presence of senior males, but he remains careful to acknowledge them. When five adult males in a row passed Alofu, including the beta male, Kalunde, Alofu nipple-pressed 18 times, including once with both hands simultaneously while bipedal. One could speculate that Alofu was visually signaling his pant-grunt by showing this pattern to the males. use of a bipedal posture and both hands may have added amplitude to the message?