Twenty years with bonnet macaques
Long-term study on the demography and social evolution in wild bonnet macaques
Distribution, morphology, behavioural ecology
The bonnet macaque, a ubiquitous but endemic primate of peninsular India, has been celebrated through art, sculpture and literature as an integral part of southern Indian culture for almost over two thousand years. And yet we know so little of this species, considered one of our most important agricultural pests. The bonnet macaque is believed to consist of two subspecies with subtle morphological differences, with the southern subspecies restricted to southeastern India. Over the last year, we have examined the morphology, demography and life history strategies of identified individuals in selected troops of the two subspecies in two protected areas – Bandipur National Park and Kalakad-Mundanthurai Tiger Reserve – within their respective distributions. This investigation, the fieldwork for which was completed in 2011, thus aims to confirm the biological legitimacy of the two subspecies using several alternative empirical field and laboratory approaches, including geographical distribution, morphometric analysis and population genetic differentiation. The laboratory component of the analysis has also been finished. We propose to integrate all our findings and publish the complete results of the study in the coming year.
Demography, ecology and social evolution
We have also been continuing a long-term field project, begun in 2000 and proposed to continue for twenty years, investigating the demographic structure, population dynamics and socioecology of a population of wild bonnet macaques in the Bandipur National Park – Mudumalai Wildlife Sanctuary complex in the states of Karnataka and Tamil Nadu. During the last year, we have continued our demographic monitoring of twenty-two troops of the species and quantitative observations on the socioecology of five of these groups. During this work, we have been able to document the influence of the tourist traffic through these sanctuaries on the evolution of a new unimale form of social organisation in this species, characterised by certain unique demographic and behavioural features. Our studies on the socioecology of selected multi male and unimale troops in this population have allowed us to evaluate the ecological and anthropogenic factors that may have influenced the trajectories of social change in this population.
Social cognition, communication and culture
One of our long-term interests has been to investigate the social cognitive abilities of wild bonnet macaques, particularly from the perspective of both distributed and/ or embodied cognition as well as individual internal processes such as theory of mind. Our earlier studies had focused on specific behavioural processes including the acquisition of social knowledge and tactical deception in this species. Over the last year, we have been continuing our exploration of these processes and their interactions in wild bonnet macaques, drawing upon inter-disciplinary approaches such as observational studies of behaviour, philosophical analyses and mathematical modelling. We have also continued to document behavioural transmission in this macaque and are currently investigating the cognitive processes underlying tactical deception in wild groups of this species.
Temperament and personality in wild bonnet macaque
Personality, from an evolutionary perspective, represents a meta-category of the output of a suite of species-typical, relatively domain-specific, evolved psychological mechanisms designed possibly in response to the social adaptive problems recurrently faced by our primate ancestors. Early last year, we initiated a study on the evolutionary reconceptualisation of the development, structure, and processes of human personality through a closer understanding of the nature of temperament/personality in nonhuman primates that live in complex social groups, often in changing environments. We are currently in the process of devising novel methodologies that could be employed to not only define but to gain deeper insights into several issues of personality in a nonhuman primate species, typically characterised by remarkable variation in individual life-history strategies. These include, but are not restricted to, consistency/variability in personality traits, individual differences against the background of a ubiquitous species-typical nature, sex differences and similarities, age-graded and developmentally contingent personality phenomena, and the contextual determinants of personality.
Social network analysis of bonnet societies
Our research on primate societies has so far implicitly assumed that social complexity arises due to cognitively sophisticated decision-making processes exercised by each individual on the basis of individually acquired and processed information. Group- level dynamics of complex primate societies could, however, also be explained by more parsimonious, non-cognitive alternative hypotheses arising from general individual-based rules, as predicted by principles of self-organisation and chaos. In 2010, we initiated an investigation into appropriate agent-based models that could account for several emergent properties of the bonnet macaque social networks that we have earlier observed. We are interested in the role played by interactions between general rule-based behaviours and individual-specific cognitive behaviours in the emergence of social networks such as those of cercopithecine primates, which perhaps represent an intermediate stage between the simpler prosimian groups and the much more complex human societies.
- Book Chapter2014Experientially Acquired Knowledge of the Self in a Nonhuman PrimatePages 81-99 in Sangeetha Menon, Anindya Sinha and B V Sreekantan (editors) Interdisciplinary Perspectives on Consciousness and the Self, Springer, India
The pressures of developing and maintaining intricate social relationships may have led to the evolution of enhanced cognitive abilities in many social nonhuman species, particularly primates. Knowledge of the dominance ranks and social relationships of other individuals, for example, is important in evaluating one’s position in the prevailing affiliative and dominance networks within a primate society and could be acquired through direct or perceived experience. Allogrooming supplants among female bonnet macaques usually involve the subordinate female of a grooming dyad retreating at the approach of a third female, dominant to both members of the dyad, although, in a few exceptional cases, the dominant member of the dyad could, instead, retreat. Retreat by the dominant individual was observed to be positively correlated to the social attractiveness of her subordinate companion, indicating that individual females successfully evaluate social relationships among other group females. Logistic regression analysis revealed the probability of retreat of the dominant female to be significantly influenced by her own dominance rank and those of the other two interacting females. Individual macaques thus possess egotistical knowledge of their own positions, relative to those of others, in the social hierarchy and appear to, therefore, abstract and mentally represent their own personal attributes as well as those of other members of the group. The experiential acquisition of such cognitive knowledge of the self raises important questions about the possible mechanisms underlying the nature of this mental representation and the general ability to categorise social information in non-verbalizing animal species such as macaques.
- Book Chapter2014Nature and Culture in the wild: Biological foundations of behavioural traditions in non-human primatesPages 367-389 in R Narasimha and S Menon (editors) Nature and Culture Volume XIV, Part 1, Project of History of Indian Science, Philosophy and Culture Centre for Studies in Civilizations, New DelhiDownload
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A variety of mechanisms for socially facilitated learning allow animals to acquire information from the behaviour of others, and through their own modified behaviour such information can subsequently be transmitted between individuals within and across generations. Variation in such socially acquired and transmitted behaviours is unlikely to be under direct genetic control since individuals who are closely related genetically can have and pass on very different behaviours; this is also true for cultural traditions that such behaviours may have generated. Behavioural information transfer of this nature thus represents another form of inheritance that operates in many nonhuman species, including primates, in tandem with the more basic genetic system. Most behavioural traditions usually precede genetic adaptations but exert persistent directional selection for genetic variations congruent with the new patterns of behaviour since such traditions lead to the transmission of the same selective regime. Selection for the ability to learn a particular behaviour pattern more efficiently and rapidly may also lead to it becoming dependent on fewer learning trials or none at all – ultimately culminating in a partial or complete incorporation of the trait into the basic genetic inheritance system. This paper reviews principles of culture and its biological foundations, and examines the rôles that behavioural inheritance and socially transmitted cultural traditions play in the structure and dynamics of primate societies, with particular reference to data from long-term field studies on Japanese macaques and from bonnet macaques, a species endemic to peninsular India. Three principal consequences are considered: the appearance of individual behavioural traits leading to the establishment of social traditions, the rôle of stable behavioural traditions in facilitating cultural selection, and the influence of particular behavioural and life-history traits on gene-culture coevolution in nonhuman primates.
- Book2013The Macaque Connection: Cooperation and Conflict between Humans and MacaquesSeries: Developments in Primatology: Progress and Prospects, Vol. 43, Springer, New Delhi
Most successful among the non-human primates in terms of geographical distribution and adaptability to ecological habitats, macaques have existed for many thousands of years in close contact with modern humans, the only primate more successful than them. Centuries-old literary works attest to the fact that macaques have always been an intrinsic part of human lives and imaginations. In their interactions with humans, macaques play multiple roles that often transcend the boundaries of categorization. They are often, simultaneously, wildlife and domestic pets, sentient beings and experimental subjects, crop-raiding pests and religious symbols. In many parts of the tropics, macaques are an economic resource for human communities, as they provide meat and money through tourism and the animal trade. Equally, they cause much damage and bring about great economic losses due to their crop- and house-raiding tendencies. A more recent cause for alarm has been the possibility of transmission of diseases to humans due to contact with macaques. Across Asia, macaques, perhaps more than any other animal species, exemplify the multiple facets of synurbization and the conservation problems of commensal species. Humans and macaques associate in rather remarkable ways, and this volume explores the tone and nature of those human-macaque connections by focusing on various forms of interactions between macaques and humans, change in human attitudes vis-à-vis macaques over the ages, cultural views on macaques, human-macaque conflict and its conservation implications. Its holistic perspective of the myriad aspects that illustrate the singular relationship between men and macaques makes it essential reading not only for primatologists and anthropologists but also for anyone interested in the intricacies of human-animal relations.
- Book Chapter2013The Monkey in the Town’s Commons, Revisited: An Anthropogenic History of the Indian Bonnet MacaquePages 187-208 in S. Radhakrishna et al. (eds.), The Macaque Connection: Cooperation and Conflict between Humans and Macaques, Developments in Primatology: Progress and Prospects, Springer, New Delhi
- Book Chapter2013Bonnet macaque Macaca radiataPages 148-169 in A J T Johnsingh and N Manjrekar (editors) Mammals of South Asia, Volume 1, Universities Press, Hyderabad
- Journal Article2011Less than wild? Commensal primates and wildlife conservationJournal of Biosciences 36: 749-753
- Journal Article2005Ecology proposes, behaviour disposes: Ecological variability in social organization and male behavioural strategies among wild bonnet macaquesCurrent Science, 89: 1166-1179Download
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The structure and evolution of primate societies are generally shaped by ecological and social forces of natural selection. The habitat and feeding ecology of primate populations, in particular, largely determine the size of the existing social groups and the pattern of interactions between individuals within and across such groups. The bonnet macaque (Macaca radiata), an Old World monkey endemic to peninsular India, usually lives in seasonal tropical deciduous forests and occurs in typically large multimale multifemale associations. This species, however, appears to have evolved, in re- cent years, a fairly high proportion of small, but rea- sonably stable, unimale troops within one particular population in the Bandipur–Mudumalai wildlife sanc- tuaries of southern India. Demographic analyses indi- cate that, as compared to multimale troops, unimale groups are relatively depleted in subadult and juvenile males, exhibit a unique female-biased birth sex ratio and display extensive female dispersal, all of which may have arisen in response to reproductive monopo- lization by the solitary resident male. Several ecological factors, including food provisioning, may have led to the evolution of this social organization, unique for a seasonally breeding cercopithecine primate. Provisioning of primate groups also leads to a significant increase in intra-troop competition among individuals for the newly available resources. Do such individuals, however, exhibit altered behavioural strategies to alleviate social tension? Changing patterns of social interactions between adult males were also analysed for one particular troop of bonnet macaques in the Mudumalai Wildlife Sanctuary under two ecological situations – as they foraged on their natural diet and when they gathered provisioned food from tourists visiting the sanctuary. Although feeding competition increased markedly as these individuals alternated between natural foraging and competing for provisioned food, individual macaques were able to adopt appropriate social strategies under such rapidly changing eco- logical regimes. These studies demonstrate the behavioural and social plasticity of a primate species and the value of demographic studies of multiple groups and populations in different ecological environments.
- Journal Article2005Not in their genes: Phenotypic flexibility, behavioural traditions and cultural evolution in wild bonnet macaquesJournal of Bioscience 30: 51-64
- Journal Article2003Changing social strategies of wild female bonnet macaques during natural foraging and on provisioningCurrent Science 84 (6): 780-790Download
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Provisioning of free-living primate groups usually leads to a significant increase in competition among individuals for the newly available resources. Do such individuals, however, exhibit altered behavioural strategies to alleviate social tension? Changing pat- terns of social interactions between adult females was studied in a wild group of bonnet macaques (Macaca radiata) in the Mudumalai Wildlife Sanctuary, Tamil Nadu, southern India, under two conditions of forag- ing. The group spent approximately 66% of the ob- servation time foraging on its natural diet; during the remaining period the group gathered provisioned food from tourists visiting the sanctuary. Provisioning was marked by a sharp increase in aggression and feeding supplants within the group. Dominant females directed contact aggression specifically towards higher-ranked subordinates, while subordinate fe- males increased non-contact aggression towards their dominant counterparts. Allogrooming was, however, much more reciprocated at the group level during provisioning. Subordinate females also initiated rela- tively more allogrooming towards those dominant in- dividuals who were most aggressive during this period. Social tensions thus increase markedly when bonnet macaques move from natural foraging to com- petting for provisioned food; individual macaques, however, can adopt appropriate social strategies un- der such rapidly changing ecological regimes.