Charmalie A. D. Nahallage

Acquisition and development of stone handling behavior in infant Japanese macaques

(Section of E cology ,D epartment of E cology and S ocial B eha vior,Primate R esearchInstitute, K yoto U niversity,41-2 K anrin, Inuyama, A ichi 484-8506, Japan)(Accepted: 5 July 2007)SummaryIn this study we systematically investigate the mode of acquisition and the developmentalprocess of stone handling, a form of solitary object play , in a capti ve troop of Japanesemacaques (Macaca fuscata ) housed in an outdoor enclosure at the K yoto U niversity PrimateResearch Institute, Japan. T his study w as conducted to evaluate tw o alternati ve hypothesesregarding the mode of acquisition of stone handling in infants: (1) en vironmental stimuli(availability of and exposure to stones) and (2) social stimuli (exposure to stone handlingindi viduals). Early exposure to stones in the en vironment had no signiÞcant effect on wheninfants acquired the beha vior . N o signiÞcant correlations were recognized between the ageof stone handling acquisition and number of stones encountered per hour from birth to ac-quisition, or the time spent in a speciÞc area of the enclosure as a function of the number ofavailable stones therein. H ow ever, being exposed to a stone handling m odel(s) w as a socialstimulus that had an effect on the age of acquisition, with a signiÞcant negative correlationbetween a m otherO s stone handling frequenc y and the age of acquisition by her infant. Infantsof non-stone handling m others acquired the beha vior much later than others. Inf ant peerswho acquired stone handling earlier played no signiÞcant role as stone handling m odels. O fthe factors tested here, the timing of acquisition depended m ainly on the level of proximityto a demonstrator and the frequenc y at w hich those available demonstrators performed thebeha vior .K eywor ds : solitary object play, proximity , beha vioral m odel, stimulus enhancement, trans-mission.

Diurnal Primates in Sri Lanka and People's Perception of Them

Abstract: Five species of non-human primates occur in Sri Lanka—the toque macaque (Macaca sinica), purple-faced langur (Trachypithecus vetulus), slender lorises (Loris tardigradus and Loris lydekkarianus) and the gray langur (Semnopithecus priam thersites). The primates of Sri Lanka are endemic and considered to be Critically Endangered or Endangered. Here we report on some observations, information from interviews with local people regarding primate-human interactions, and also morphological differences in the subspecies we observed during field visits in 2004, 2005, and 2007. When asked, most people stated that they believed that primate populations had increased over the years, and many consider them to be agricultural pests due to the damage they inflict on crops. Due to religious beliefs, hunting and killing of primates were reported in low frequency, but some eat the meat of purple-faced langur for medicinal purposes. The most common methods people use to prevent monkeys from damaging crops are throwing stones, and the use of firecrackers or any other way of producing loud noises. The major threat that these primates face is the destruction of their habitat due to deforestation, human population growth and the expansion of various rural development projects. Public awareness programs for schools and through the media are needed to encourage the protection of these animals and their habitats.

Cultured Monkeys Social Learning Cast in Stones

Sixty years ago, the notion that animals could have culture was unthinkable to most behavioral scientists. Today, evidence for innovation, transmission, acquisition, long-term maintenance, and intergroup variation of behavior exists throughout the animal kingdom. What can the longitudinal and comparative study of monkeys handling stones tell us about how culture evolved in humans? Now in its 30th year, the systematic study of stone-handling behavior in multiple troops of Japanese macaques has shown that socially mediated learning is essential to explain the spread, persistence, and transformation of individual behavioral innovations among group members. The integrative research paradigm presented here can be applied to the study of various candidate behavioral traditions in other species.

Stone-throwing by Japanese macaques: form and functional aspects of a group-specific behavioral tradition

Throwing is a major behavioral component of hominid evolution. Comparison of this behavior across a broad range of non-human primate species is needed to elucidate the phylogenetic constraints on throwing behavior. In this study of stone-throwing in Japanese macaques, we present a systematic multi-group comparison of the frequency and prevalence of this behavior as well as detailed descriptions and quantitative data on the form, context, and possible social transmission of stone-throwing. Stone-throws were mainly underarm, performed from a tripedal posture, and often accompanied by repeated vertical leaps. We found marked individual hand preferences for throwing, but no consistent group-level handedness. Our results support the hypotheses relating body posture, throwing style, and handedness in throwing by primates. Based on the analysis of the contexts that may elicit the behavior, we postulate that unaimed stone-throwing in Japanese macaques may serve to augment the effect of agonistic displays, and accordingly, can be regarded as spontaneous tool-use. Our findings are consistent with the comparative data using modern non-human primate species to model the structural processes and functional aspects of throwing evolution in early hominids. This study supports the view that tool-use evolves from initially non-functional behaviors, such as stone handling, which is a form of object play. Stone-throwing by Japanese macaques meets several criteria of a behavioral tradition, including group-specificity. This first report of a stone-tool-use tradition in Japanese macaques is of direct relevance to the question of the evolution of stone technology in hominids.

Comparison of stone handling behavior in two macaque species: implications for the role of phylogeny and environment in primate cultural variation

This study describes the stone handling (SH) behavior of captive rhesus macaques and compares it with that of a captive troop of Japanese macaques with reference to the relative contributions of phylogeny‐driven behavioral propensities, environmental differences and socially facilitated learning to the formation of culture. These systematically collected data demonstrate for the first time that two closely related macaque species might share a common cultural behavior, SH. The rhesus troop displayed SH behavioral patterns that was already described in Japanese macaque troops. The one exception was a new pattern not yet seen in any Japanese macaque troop. Differences in the physical environment of the two study enclosures may be responsible for some of the variation in observed SH behavioral patterns in these two troops. These data support the idea that environmental factors can be important for the formation of cultural variation, when the key materials needed to perform the behavior are present in both habitats (stones). Our results are consistent with the prediction made by Huffman and Hirata [The biology of tradition: Models and evidence. Cambridge: Cambridge University Press. p 267–296] that an interactive triad of phylogenetic, environmental and social factors can be responsible for the formation of cultural variation in primates. Am. J. Primatol. 70:1124–1132, 2008.

Stone handling behavior in rhesus macaques (Macaca mulatta), a behavioral propensity for solitary object play shared with Japanese macaques

Stone handling (SH) behavior was systematically studied in a captive troop of rhesus macaques housed at the Primate Research Institute of Kyoto University, and compared with the results of long-term studies of this behavior in Japanese macaques, to evaluate the similarities of SH behavior in these two closely related species. Similar to Japanese macaques, rhesus macaques showed age-related differences in SH. Young animals were more active and displayed more SH patterns and bouts than did adults. Furthermore, the young displayed SH at a higher frequency and their bouts were of a shorter duration, compared to adults. Young adults were more active and displayed more patterns than did older adults. On the other hand, older adults were more conservative and displayed fewer patterns, and engaged in them for longer durations. All individuals displayed SH more frequently in relaxed environmental and social conditions. While lacking an apparent immediate adaptive value, practice of the behavior has been proposed to have long-term functional value for neural and cognitive development in the young and for the maintenance or repair of neuro-pathways in aging macaques that habitually perform the behavior. The results presented here are consistent with what we know about Japanese macaque SH. Given the uniformity of SH behavioral parameters and these two macaque species’ close phylogenetic relatedness, we propose that a similar functional and adaptive value for SH can be inferred for rhesus macaques.

Stone handling, an object play behaviour in macaques: welfare and neurological health implications of a bio-culturally driven tradition

Object play in primates is viewed as generally having no immediate functional purpose, limited for the most part to immature individuals. At the proximate level, the occurrence of object play in immatures is regarded as being intrinsically self-rewarding, with the ultimate function of supporting motoneuronal development and the acquisition of skills necessary to prepare them for survival as adults. Stone handling (SH), a solitary object play behaviour occurs, and has been studied, in multiple free-ranging and captive troops of provisioned Japanese macaques, as well as rhesus and long-tailed macaques for over 35 years now. A review of our combined findings from these observations reveal that infants acquire SH in the first 3-4 months of life and exhibit increasingly more complex and varied behavioural patterns with age. The longitudinal data shows that many individuals maintain this activity throughout life, practicing it under relaxed ecological and social conditions. The ultimate function may be bimodal, promoting motor development in young and neural maintenance and regeneration in adult and aging individuals.

Macaque–Human Interactions in Past and Present-Day Sri Lanka

Sri Lanka’s toque macaque is an endemic endangered species. Current information about the nature and diversity of their interactions with humans are limited. We conducted 307 interviews across the country using a standardized questionnaire to help clarify this. Overall, 51% believed that primate numbers were increasing, but trends varied regionally, with some provinces reporting noticeable decreases in monkey sightings while others reported increased visits by monkeys to garden plots. This may be due to variation in the intensity of human development and forest fragmentation either forcing primates closer to human habitation in search of food or driving them closer to local extinction in more developed urban and industry based provinces. This terrestrial, omnivorous species is considered a pest. For the most part they are tolerated, but in certain provinces they are responsible for significant economic damage to crops, and are treated more severely. Both Buddhists and Hindus treat macaques with reverence, and they are particularly visible in the vicinity of temples and historical areas because of a continuous supply of religious food offerings, from which feeding on is tolerated. The killing of any wild animal, including primates is against the law and prohibited by religious beliefs. Nonetheless, hunting for food and a rich belief array of medicinal and ritual uses was reported to occur at very low frequency in rural areas