Abstracts
Abstracts of presentations by invited speakers
Plenary speakers
Biomechanical analysis of the Laetoli footprint trails
Robin H Crompton1, Todd Pataky1, Russell Savage1, William I Sellers2
1School of Biomedical Sciences, University of Liverpool, Sherrington Buildings, Ashton Street, Liverpool L69 3GE, UK
2Faculty of Life Sciences, 3.614 Stopford Building, The University of Manchester, Oxford Road, Manchester M13 9PT, UK
Email: rhcromp@liverpool.ac.uk
The Laetoli footprint trails, dating to around 3.8 Ma and most commonly attributed to the only early hominin known from postcranial fossils in the Laetolil beds, Australopithecus afarensis remain our most direct evidence of the function and biomechanics of the foot in early human ancestors. Just as gait of Au. afarensis continues to be the subject of much debate, primarily as to whether it would have been upright ('stiff') walking or bent-hip, bent-knee ('compliant') walking, so interpretations of the footprints, most based largely on the juvenile, G-1 trackway, range from claims, as recent as 2007, that they are completely consistent with a chimpanzee-like bipedalism, (and hence compatible with a recent knucklewalking ancestry) to claims that they are completely modern in functional aspect. We report progress in biomechanical analysis of the Laetoli footprint trails based primarily on on: 1) quantitative experimental studies of human foot pressure in a variety of gaits both directly over a pressure/forceplate combination and measured under 4 mm of fine damp sand, and 2) both forwards-dynamics and finite-elements modelling of foot pressure and footprint formation.
Darwin, Time and Morphology: Constraints on Sociality in Primates and their Implications for Evolution
Robin I.M. Dunbar
Institute of Cognitive & Evolutionary Anthropology, University of Oxford, 64 Banbury Road, Oxford, OX2 6PN, UK
Email: robin.dunbar@anthro.ox.ac.uk
Primates are intensely social animals, and this imposes a constraint on a species’ capacity to occupy different kinds of habitats since animals must be able to maintain groups of a minimum size to cope with the demands of a particular habitat. Two key constraints in this respect are time and predation risk, both of which are influenced by morphology. Time is about animals’ abilities to balance their time budgets while meeting both the demands of foraging and nutrient intake and the maintenance of the social bonds that ensure group cohesion through time. When species cannot balance their time budgets, they must either evolve a new adaptive strategy or go extinct. I will consider the implications of our time budget models for species evolutionary history and extinction risk.
Form and function in the primate skeleton: guenon case studies
Sarah Elton
Hull York Medical School, University of Hull, Cottingham Road, Hull, HU6 7RX, UK
Email: sarah.elton@hyms.ac.uk
Primate skeletal morphology is influenced by a wide array of factors: evolutionary history, developmental plasticity, geography, environment, social behaviour and ecology (including feeding and locomotion). These factors need to be teased apart in order to understand the relationship between form and function. In this presentation I will review some recent work on guenon craniofacial form that illustrates how multiple factors, only some of which are directly related to function, influence morphology (both size and shape). I will also use the terrestrial guenons as a case study to demonstrate how postcranial morphology in a group of closely related primates adapts in response to different locomotor and habitat pressures.
Darwin with a smile
Prof Jan A.R.A.M. van Hooff
Professor Emeritus, Behavioural Biology Group, Utrecht University, The Netherlands
Email: jaramvanhooff@planet.nl
This year we commemorate the genius who gave us an explanatory model for the phenomenon of evolution. He was also one of the first to make scientifically reliable observations about animal behaviour; see his third famous book: “The Expression of the Emotions in Man and Animals”. Darwin regarded, contrary to what many were willing to accept, also the mind as a product of evolution. And yes, he found evidence that there is evolutionary continuity in the behavioural expression of mental states, especially in primate facial expressions. A century later new approaches have revived the interest in our expressive behaviour. They even reveal the evolutionary origins of such “unique” human attributes as our ‘laughter’ and ‘sense of humour’. A good reason to look at this with a smile
Linking morphology, behaviour and ecology: how reliable are inferences from fragmentary hominin remains?
Prof. Gabriele A. Macho
University of Bradford, Bradford BD7 1DP, UK
Email: G.Macho@Bradford.ac.uk
The late Miocene to early Pleistocene is one of the most exciting periods in hominin evolution, as it marks the key innovations in hominin morphology and behaviour, largely triggered by environmental changes. Elucidating these changes, processes and underlying causes is however fraught with problems, not least because of the sparse and fragmentary nature of the fossil record itself. Where sufficient material is available, phylogenetic and developmental constraints on morphology may mask behavioural changes already established (“form follows function”). Evolutionary anthropologists have therefore relied on broad comparative analyses of extant (and some extinct) taxa to infer evolutionary changes in morphology and behavior, or they have used modern analogues to deduce the behaviour of extinct species. In the case of hominins, chimpanzees are commonly used as such modern analogues given their close genetic relationship with modern humans. Whether chimpanzees are indeed suited for functional and behavioural inferences has been called into question however. Over the last few years it has become increasingly evident that early hominins may have been more comparable to gorillas in dietary adaptations and habitat exploitation, and may have differed from both chimpanzees and gorillas in positional behavior. Here we review the evidence and present a new analytical approach, which throws further light on the locomotor behavior of A. anamensis and A. afarensis.
This work is funded by The Leverhulme Trust and the Natural Environment Research Council.
Applying numbers to the three Fs: form, function, and phylogeny
Todd C. Rae
Centre for Research in Evolutionary Anthropology, Roehampton University, Holybourne Avenue, London SW15 4JD
Email: t.rae@roehampton.ac.uk
Throughout the history of evolutionary thought, there has been an uncomfortable tension in morphology between those intent on exploring function and those with an interest in phylogeny. To many, the relationship between form and function is self-evident, and the relationship between form and phylogeny is obvious and tractable, but that between function and phylogeny is a philosophical nightmare. While some maintain that phylogeneticists should concentrate only on non-functional traits (however they may be defined), others argue that phylogeny can only be inferred from functional characteristics, as they are under the strictest control of natural selection. Even less straightforward is how quantitative traits should be treated, as most phylogeny reconstruction computer programs require that data be coded into discrete states for input, and the translation of quantitative data into codes is tantamount to violence in the eyes of many.
To explore these issues, a large dataset of cercopithecine primate postcranial measurements was analysed using a number of techniques, reflecting a wide range of approaches to the problem of function and phylogeny. The data demonstrate a number of issues, including sensitivity to dominant locomotor pattern, the effect of allometry on attempts to scale data to body size, and the relationship of functional features to phylogenetic relationships, which highlight the opportunities and difficulties in inferring function and phylogeny from form. While it may not be possible to ‘solve’ the function/phylogeny conundrum, this example demonstrates the utility of some approaches to the problem, and the failure of others.
Oral presentations (9):
Sexual dimorphism and extended cranial growth in the great apes: links between morphology and social behaviour
Katharine Balolia
University College London, Department of Anthropology, 14 Taviton Street, London, WC1H 0BW
Email: k.balolia@ucl.ac.uk
Sexual dimorphism and reproductive behaviour have long been linked in that species whose males exhibit a high intensity or frequency of intrasexual competition show greater levels of body mass dimorphism, compared to species where males show lower levels of intraspecific aggression. Of additional relevance is the timing of maturity with respect to the attainment of full body size, in that sex differences in the timing of growth cessation are indicative of a social structure with high levels of intraspecific male-male competition. This paper describes how cranial dimorphism in four species of great ape (Pan troglodytes, Pan paniscus, Gorilla gorilla and Pongo pygmaeus) is achieved, through the analysis of male and female growth following dental maturity. Results are used to investigate the relationship between social structure, social dominance and cranial growth, particularly focusing on the areas of the skull which demonstrate extended growth or shape change with age after dental maturity has been reached. Patterns of cranial growth are interpreted in conjunction with overall levels of cranial dimorphism, life history characteristics, ecological factors and the nature of intrasexual competition prevalent in these four great ape species. Results are also discussed in terms of their relevance for the reconstruction of social behaviour in extinct hominin species.
Social networks in adult female rhesus macaques
Lauren J N Brent, Ann MacLarnon, and Stuart Semple
School of Human & Life Sciences, Roehampton University, Holybourne Avenue, London SW15 4JD.
Email: L.Brent@roehampton.ac.uk
Social network analysis is a powerful tool which provides quantitative measures of social structure and relationships. Advances in computational power and development of new software have recently made this technique practical for primatologists. Social network analysis may provide a vast scope of insights into the causes and consequences of primate sociality. Here, we examine the grooming and proximity networks of adult female rhesus macaques. Behavioural data collected over 9-months were analysed for 21 adult females from a free-ranging group on Cayo Santiago. Social network analysis was performed using UCINET and SOCPROG software. The proximity network was more tightly connected than the grooming network. Dominance rank was significantly related to many measures of social integration for both networks, indicating that higher ranking females were more socially integrated. Despite this finding, individuals with the highest levels of integration were not the same in both networks. Social networks were more tightly connected in the mating season compared to the birth season. This may be due to differing levels of female competition, consortships with males, or the presence of infants. This is one of the first studies to use social network analysis to examine social structure in a free-ranging nonhuman primate. In addition to the novel insights this study may provide into rhesus macaque sociality, it also represents a first step toward generating the social network data necessary for potentially fruitful inter-species comparisons.
The impact of social events on urinary cortisol in zoo housed spider monkeys
Nick Davis 1,2,3, Colleen M. Schaffner1, Tessa E. Smith 2
1Department of Psychology, University of Chester, Parkgate Road, Chester, CH1 4BJ
2Department of Biology, University of Chester, Parkgate Road, Chester, CH1 4BJ
3North of England Zoological Society, Upton, Chester, CH2 1LH
Email: N.Davis@chesterzoo.org
Over a six year period three different types of social stressors were examined in a group of 8-13 spider monkeys (Ateles geoffroyi rufiventris) housed at Chester Zoo. Their resulting physiological stress response was measured through changes in urinary cortisol the week prior to, the day of and the week following a stressor event. The three stressors were aggressive events (minor, severe or lethal), reproductive events (oestrus, mating and births) and separation events (separation <24h, separation >24h and reintroduction). Analyses were performed using linear mixed models. The first model tested for the overall impact of the three types of stressors and revealed that aggression led to the largest effect on urinary cortisol, regardless of time or role in the aggression. When we examined the type of stressors individually, the model which best explained the data for aggression revealed that targets and bystanders had the highest levels of cortisol on the day of aggression for severe and lethal aggression, respectively. When examining the reproductive events, the best model revealed that cortisol levels were significantly elevated in the mother the week prior to and the day of birth. Finally, in the case of separations, cortisol was elevated when an individual was separated for >24h relative to separations < 24h or reintroductions. This study contributes to our understanding of the physiological responses to stressors in a zoo environment and has implications for animal management.
Correlates of stress and anxiety in wild male olive baboons (Papio hamadryas anubis) in Gashaka-Gumti National Park, Nigeria
Jacklyn J. Ellis, Stuart Semple, Ann MacLarnon
School of Human & Life Sciences, Roehampton University, Holybourne Avenue, London SW15 4JD
Email: j_j_ellis@hotmail.com
Sociality can confer many benefits to gregarious animals, however, group living does not come without associated costs. One of the major costs is that social life can be stressful. This study investigates the behavioural and social correlates of stress and anxiety in group-living wild male olive baboons (Papio hamadryas anubis) in Gashaka-Gumti National Park, Nigeria, and presents the first examination of these correlates for male baboons living in a forested environment. Faecal glucocorticoid concentrations were used to quantify the physiological stress response, while rates of both total self-directed behaviours and self-scratching were used to quantify anxiety. EIA techniques were employed to analyse glucocorticoid concentrations from the faecal samples, and behavioural data were collected using forty-five minute continuous focal animal sampling and ad libitum sampling. Mean glucocorticoid concentrations were found to correlate negatively with the mean rate of mounting adult males. Total self-directed behaviour rate was negatively correlated with the mean rate of being presented to by adult females. Both total self-directed behaviour rate and self-scratching rate were positively correlated with the percentage of time spent with a male as a nearest neighbour or social partner. These results suggest that physiological stress and behavioural anxiety are affected by different aspects of social life.
Energetic advantages of large body size in orang-utans
Mark E. Harrison and Helen C. Morrogh-Bernard
Wildlife Research Group, The Anatomy School, University of Cambridge
E-mail: harrison_me@hotmail.com
Previous researchers have hypothesised that large body size is energetically advantageous for orang-utans, because of (a) increased ability for fibre digestion, (b) greater absolute and relative fat storage capacity, which can be metabolised during periods of energetic shortfall and (c) lower mass-specific metabolic rates in larger animals. These hypotheses were formulated primarily from observations of orang-utans in captivity, where obesity is frequently problematic and, moreover, in mast-fruiting dipterocarp forests, which experience dramatic fluctuations in fruit availability, of a degree not generally experienced by apes elsewhere. In this paper, we re-assess these hypotheses in light of new information on energy and nutrient intake in orang-utans in the non-masting Sabangau peat-swamp forest, Central Borneo (collected by the authors), and in African apes. Similar to masting habitats, Sabangau orang-utans Sabangau experienced prolonged negative energy balance, with occasional energy intake far in excess of requirements, and an average 34% (maximum 52%) of their energy potentially obtained from fibre. Combined with low overall energy intake, this indicates that fibre fermentation is as essential for orang-utan survival in non-masting forests, as in masting habitats. Similar prolonged periods of negative energy balance have not been observed in African apes, and the fibre content of orang-utan diets is intermediate between chimpanzees and gorillas. These observations support the above hypotheses, and suggest (i) that orang-utans face greater difficulties in meeting energy requirements than are typically faced by African apes and (ii) that energetic pressures have led to orang-utans evolving the maximum body size commensurate with an arboreal lifestyle.
Patterns of water use in primates
Erica Kempf
Department of Archaeology, University of York and Hull York Medical School
Email: ek538@york.ac.uk
Primate biology and ecology have been studied extensively for many species, but have focused primarily on the terrestrial and arboreal aspects of the environment. However, primates also interact with water, with at least 10% of primate species being reported to have significant interactions with water. Based on the available literature, these interactions seem to be influenced by five major factors: diet, predation, range, thermoregulation and display. Diet and predation are directly linked to an individual’s survival, while range, thermoregulation and display are very important to understanding energetic costs, breeding success and resource acquisition. Overall, primate species interactions with water are important in gaining a more complete understanding of the individual species that perform them, as well as a more general picture of primate behaviour as it relates to aquatic environments. Additionally, the use of aquatic environments by extant primates can be used to more accurately reconstruct ecology and behaviour in extinct primates, including hominins.
Sex differences in sibling caretaking by cotton-top tamarins: acquiring skills or paying dues?
William C McGrew and Peter.J. Dannatt
Leverhulme Centre for Human Evolutionary Studies, Dept. of Biological Anthropology, University of Cambridge, Fitzwilliam St., Cambridge CB2 1QH,
Email: wcm21@cam.ac.uk
Carrying of younger siblings in cooperative rearing as is characteristic of marmosets and tamarins (Callitrichidae) is costly in time, energy, and risk, and therefore demands explanation. This study looked at a captive colony of cotton-top tamarin (Saguinus oedipus), in order to test two competing hypotheses: Carrying infants in order to gain allo-parental caretaking experience, or carrying as a ‘payment’ to be allowed to stay in the family-group. Sex differences in life-history strategies (male-biased philopatry versus female-biased dispersal) suggest that while both sexes need to gain parental experience, males should carry more and for longer. We found such a sex difference in infant-carrying, with male data fitting the ‘pay-to-stay’ hypothesis, while female data agreed with the ‘carry-for-experience’ model.
Cognitive enrichment in chimpanzees
Lisa Riley1,2, Ann MacLarnon3 and Deborah Custance1
1 Department of Psychology, Goldsmiths College, University of London, New Cross, London, SE14 6NW.
2 School of Human & Life Sciences, Roehampton University, Holybourne Avenue
London SW15 4JD.
Email: sandjriley@hotmail.com
Environmental enrichment typically overlooks the cognitive requirements of captive chimpanzees. We considered whether cognitive challenge is enriching for chimpanzees by decreasing the stress response. Seven chimpanzees (3 males, 4 females) from Twycross Zoo, UK, were given the opportunity to learn (via independent and social-learning strategies) the solution to a complex food-acquisition task (considered to be a significant cognitive challenge). Stress was assessed by investigating changes in faecal glucocorticoid metabolite concentration (fGCM) (ng/g faecal dry weight) over several weeks pre-, during- and post-exposure to the social learning paradigm. As a group, the chimpanzees’ fGCM decreased significantly when presented with cognitive challenge (median fGCM pre 289.68 ng/g, during 257.16 ng/g, post 302.31 ng/g, N=54, df=2, χ2=19.59, exact P<0.001). Female participants showed a significantly reduced baseline stress response during cognitive challenge (median fGCM pre 256.68 ng/g, during 186.39 ng/g, post 230.02 ng/g, N=33, df=2, χ2=12.606, exact P=0.002). Male participants displayed no such reduction, and tended to become stressed when the challenge was removed post exposure (median fGCM pre 335.19 ng/g, during 335.92 ng/g, post 470.38 ng/g, N=21, df=2, χ2=4.952, NS). Preliminary data suggests that an individual’s behavioural response to cognitive challenge may also be an important indicator of stress. Cognitive enrichment may improve the welfare of captive chimpanzees, particularly females and those of a low social rank.
Vocal traditions in communities of wild spider monkeys
Claire Santorelli1; Colleen Schaffner1; Filippo Aureli2
1Department of Psychology, University of Chester, UK
2Research Centre in Evolutionary Anthropology, Liverpool John Moores University, UK
Email : c.santorelli@chester.ac.uk
Variation in vocalisations between species, and within a species, can function as highly conspicuous signals of group membership and, under certain conditions, indicate the presence of traditions. We investigated the extent to which acoustic variation in the whinny calls of spider monkeys (Ateles geoffroyi) indicated the existence of vocal traditions. We recorded vocalisations in three communities of wild spider monkeys living in two different field sites in Mexico and Costa Rica. Nine temporal and four frequency parameters were measured from multiple whinny calls of 43 individuals. Principle component analysis and discriminant function analysis procedures were used to assign calls either to field sites, specific communities or to individuals. Significant vocal variation was found between the two field sites, between neighbouring communities in Mexico, and among individuals in two of the communities. Variation in correct call classification rates shown for individuals’ calls in these two communities may reflect differences in recent demographic patterns. In one community group membership remained relatively stable, whereas one experienced high immigration levels over a short period of time. Genetic drift and adaptation to local habitat are likely explanations for between site variations, which do not support the presence of traditions. Social learning, however, is likely to account for variation between the Mexico communities’ calls, which does provide evidence of dialect traditions between these two communities.
Poster presentations (9):
The ontogeny of the great ape scapula
Anna Barros
UCL
Email: anna.pepe.barros@googlemail.com
The discovery of an infant Australopithecus specimen and associated complete scapula in 2002 (Alemseged et al, 2006) prompted more questions than answers regarding the importance and degree of arboreality in Australopithecus. Why does this infant appear to have scapular proportions more similar to those of Gorilla than to Pan or Homo sapiens, which are phylogenetically closer to Australopithecus than is Gorilla? Does scapular shape reflect function or phylogeny (or both)? Studies tracking the ontogenetic development of the scapula during infancy are scarce, as are studies attempting to link muscle action (locomotion) to scapular development. The current study aims to track Pan and Gorilla scapular growth from 0 to 11 years (infants and juveniles) using geometric morphometrics. Published locomotor age classes and EMG studies were used to predict how bone may respond to changing muscle strains during development. Apart from changes at the scapular borders, the results show that the glenoid fossa and the scapular spine rotate cranially at a specific stage in both species, (an unexpected and novel finding). Function, therefore, may contribute more significantly to scapular shape than previously thought, albeit constrained by certain genetic boundaries.
Inter- and Intraspecific Craniofacial Morphology in Old World Monkeys: Environments, Dietary Adaptations and Facial Mechanics
Jason Dunn
Mammal Ecology & Environments Group, Hull-York Medical School, The University of York, Heslington, York YO10 5DD
Email: Jason.Dunn@hyms.ac.uk
The Old World monkeys exhibit considerable interspecific diversity in morphology, ecology and behaviour. Some species, such as vervets and red colobus monkeys, also show striking intraspecific differences. These relate in part to geography, with some studies identifying significant clinal variation. Environmental factors also affect morphology in these groups. However, geography, environment and the interactions between the two do not account for all the observed variance. Diet has been shown in numerous studies to have an impact on morphology. Thus, in my PhD project I will use geometric morphometric data to explore the contribution of diet to inter- and intraspecific variations in Old World monkey morphology. I will assess its relative importance compared to spatial and environmental factors, as well as addressing its interactions with these variables. Geometric morphometrics is an ideal tool for this study, as the technique is powerful enough to identify even subtle variations in morphology. If diet is a major factor in creating differences within and between species, this may be reflected in differential craniofacial mechanics and hence morphological variation. Finite element analysis is a technique that allows the estimation of masticatory stress and strain on a skull under a given load. To augment the geometric morphometric study and produce detailed, multi-proxy models for morphological differentiation, I will use finite element analysis to load Old World monkey skulls according to different dietary regimens. Establishing clear ties between diet and morphology has obvious implications for reconstructing the ecology of fossil primates, and may even help to interpret variation in the hominin fossil record. No less importantly, identifying even small morphological differences between animal populations may denote ecological separation and thus emphasize biodiversity and inform conservation priorities.
Development of social skills and social networks in captive infant and juvenile chimpanzees (Pan troglodytes)
Samina H. Farooqi & Nicola F. Koyama
Research Centre for Evolutionary Anthropology and Palaeoecology, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool
Email: S.H.Farooqi@2007.ljmu.ac.uk
It has been suggested that social skills are critical to establish and maintain social relationships with group members. This study documents the development of social skills and social networks of infant and juvenile chimpanzees (Pan troglodytes) living in Chester Zoo. Changes in spatial interactions, such as sitting in contact and proximity, and in social interactions, such as grooming and play, of infants with mothers and other group members were observed during a 9-month study. First, we found a decrease in suckling and approaches to others over the 9 months. Second, as infants grew older time spent in sitting in contact decreased whereas time spent in proximity increased. In addition, grooming received from mothers and other individuals decreased over time probably because infants were involved in more social interactions such as play, the duration of which increased as infants achieved more social independence. Time spent in social interactions with other social partners (i.e, excluding their mother for infants and excluding their infant for mothers) increased over time. The number of social partners was higher for infants than for their mothers. The findings suggest that as infant and juvenile chimpanzees develop social skills and gain independence from the mothers they start to form relationships with other social partners.
Primate research opportunities at Howletts and Port Lympne Wild Animal Parks
Mark Kingston Jones1 and Nathalie Laurence2
1. Howletts and Port Lympne Wild Animal Parks
2. The Aspinall Foundation
Email:
Howletts and Port Lympne Wild Animal Parks in Kent were founded by the late John Aspinall, and are now managed by The Aspinall Foundation – a charity created in 1984 to oversee both the parks and in-situ conservation projects for endangered species. These collections have grown extensively and now house 28 species of primate. This includes the world’s largest captive population (currently 75) of Western Lowland Gorilla (Gorilla gorilla gorilla), nearly half of all captive Javan gibbons (Hylobates moloch) in pairs and family groups, and an extensive collection of Indonesian langurs and leaf eater monkeys - some found nowhere else outside their native countries. In addition we hold several species housed in only a handful of collections, such as the Greater bamboo lemur (Prolemur simus), a breeding group of drill (Mandrill leucophaeus), two male crowned sifaka (Propithecus verreauxi coronatus) and a growing group of Heck’s macaques (Macaca hecki). The parks have always aimed to pioneer captive breeding and husbandry techniques, while contributing to our knowledge of species’ wild counterparts. Due to continued breeding success, many of the primates at our parks have reached a stage where the size and number of social groups affords researchers valuable opportunities to conduct behavioural and ecology focused research without the variables incurred by multi-institutional studies. We therefore hope to create collaborations with external researchers in order to continue with these aims.
Dispersal and reproduction in reintroduced western gorillas (Gorilla g. gorilla)
T. King and C. Chamberlan
Affiliation: The Aspinall Foundation.
Email:
We present here observations of dispersal and reproduction made during long-term post- release monitoring of groups of rehabilitated western gorillas reintroduced within the species former range. Emigration of five males aged 9.5 to 12.1 years (median 11.8) was gradual, taking six to 16 months (median 9), followed by one or more sudden and rapid solitary excursions outside their established home ranges. Female dispersal was also often gradual, final emigration occurring up to 13 months after initial temporary dispersals. Estimated age of nine females at the first signs of dispersal ranged from 6.3 to 10.2 years (median 7.3). These included one permanent and four temporary female transfers, while sudden female emigration without transfer was observed following agonistic interunit encounters. Cohesion of an all female group was recorded when three adult females with one infant remained intact during a four-month period before the return of the group silverback. Estimated age of six females at first birth ranged from 8.5 to 16.5 years (median 10). All, but one, were still in their ‘natal’ group. However, four became pregnant during a 17-month phase of periodic but temporary transfers between their group, which lacked a full-grown male, and a solitary silverback. Our observations suggest that dispersal of young adult males is most likely influenced by the perceived availability of potential mates, while female dispersal appears in some cases to be linked to improved breeding opportunities outside their ‘natal’ group, but in others to avoidance of physical aggression during agonistic interunit encounters.
Using digit ratios (2D:4D) to predict the social systems of extinct hominids
Emma Nelson1 Campbell Rolian2 and Lisa Cashmore3
1. Department of Archaeology, University of Liverpool, L69 3BX
2. Department of Cell Biology and Anatomy, University of Calgary, T2N 4N1,
3. Centre for the Archaeology of Human Origins (CAHO), University of Southampton, SO17 1BJ
Email: Emma.Nelson@liverpool.ac.uk
Social systems are notoriously difficult to identify in the hominid fossil record due to difficulties in estimating body size dimorphism from fragmentary remains and in hominins, low canine size dimorphism. Here we attempt to reconstruct the social systems of three fossil hominid taxa (Hispanopithecus laietanus, Australopithecus afarensis and Homo neanderthalensis) by comparing their second-to-fourth digit length ratios (2D:4D) to those of extant hominoids. Recent studies have shown that 2D:4D, a putative biomarker for prenatal androgen effects (PAE), co-varies with anthropoid social systems: pair-bonded taxa have significantly higher 2D:4D ratios (low PAE) than non-pair bonded species, with the strongest relationships shown in apes. Here we use information on extant anthropoids (n=1164) and discriminant function analysis to identify social systems from 2D:4D predicted from bone ratios of fossilised proximal phalanges (II and IV). Results: Neanderthals and Hi. laietanus are classified as non-pair-bonded, while Au. afarensis groups with pair-bonded taxa. Small fossil sample sizes and possible taphonomic effects on sampling and bone length preclude drawing firm conclusions using this method. However, it is possible that as more fossil hand bones become available digit ratios could supplement current techniques used for reconstructing the social systems of fossil hominids.
Chimpanzee gut kinetics – molecular analysis of faecal samples for Pan troglodytes, Kibale National Park, Uganda
Caroline Phillips and Leslie A Knapp
Department of Biological Anthropology, University of Cambridge, Cambridge, CB2 1QH
Email: cap60@cam.ac.uk
Direct observations of great apes’ feeding can greatly illuminate their diet, however, such behavioural data can only be collected at fewer than 20 per cent of study sites; those having successfully habituated populations. New, integrated and non-invasive approaches are needed to yield dietary data on remaining ape populations, especially those unlikely to be habituated. An area of dietary analysis receiving little attention in wild populations is that of gut kinetics; the retention-time and passage-rate of ingesta (Milton and Demment 1988). Here I present a non-invasive protocol for the future analysis of gut kinetics for various food items included within the diet of an observable population of Pan troglodytes in Kibale National Park, Uganda. First, floral and faunal DNA sequences from faecal samples collected from adult males and females will be amplified and extracted. Second, a comparison with known genomes and those extracted from on-site reference samples will be conducted. Third, the extracted sequences will then be cross validated with observations of food intake for the same adult males and females in order to assess passage rate of food items for this wild population.
Reference
Milton, K and Demment, M.W. 1988. Chimpanzees fed high and low fiber diets and comparison with human data. Journal of Nutrition. 118, 1082-1088.
Assessing the impact of anthropogenic activities on the distribution of proboscis monkeys (Nasalis larvatus) in Danau Sentarum National Park, West Kalimantan, Indonesia
James Robins
Department of Anthropology and Geography, Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford OX3 0BP, UK
Email: stleonards4@hotmail.co.uk
Danau Sentarum National Park in West Kalimantan, Indonesia, is one of the few inland areas of Borneo to support a large population of proboscis monkeys (Nasalis larvatus). Preliminary surveys conducted in 1994 revealed the local population to be one of the world’s largest despite notable fragmentation and disturbance to riverine habitat. To better understand current habitat preferences it was necessary to assess the impact of the locally predominant anthropogenic activities. River surveys showed there to be significant differences in group numbers between wet and dry seasons due in part to the higher fishing intensity during the drier months. Habitat assessments revealed that proboscis monkeys avoid stretches of river with significantly higher river traffic and fishing activity, while restricting themselves to densely forested tall vegetation types. A series of village-based interviews focusing on the dietary preferences of local people also revealed proboscis monkeys to be under notable hunting pressure from a number of local Dayak villages in and around the national park boundary. The relative abundance of proboscis monkeys in the area is due to Islamic law preventing the locally dominant Melayu from eating primates.
Exploring the role of anthropogenic pressures and local perspectives in the conservation of a population of the grey-shanked douc langur (Pygathrix cinerea), Quang Nam province, Central Vietnam
Lauren Wright
Department of Anthropology and Geography, Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford OX3 0BP, UK
Email: lauren_wright21@yahoo.com
In 2005, a population of the Critically Endangered grey-shanked douc langur (Pygathrix cinerea) was discovered by a WWF team in Quang Nam province, Vietnam. The uniqueness of this discovery can be understood by the relatively high population count of approximately 180 individuals, and high population density within a continuous forest. A case study approach was conducted of the anthropogenic pressures confronting this population, explored in a historical framework. Interviews were conducted with the local villagers in Phuoc Ninh and Que Phuoc communes, in Nong Son district, Quang Nam province. Data were collected with three primary objectives: (1) to determine ranging patterns of the douc population and the presence of any other primate taxa in the study area, (2) to determine the degree of anthropogenic pressures by assessing livelihood practices, and lastly, (3) to identify how local people value the forest and wildlife, forest protection and resource management. Findings demonstrated that grey-shanked douc langur occurrences and extent of range have changed over the years in response to human events; that hunting and logging pressures have reduced; and that local villagers generally believe in the need to protect the forest and wildlife. The results from this investigation into this grey-shanked douc langur population, and the incorporation of the human perspective and influence, will hopefully allow for the most appropriate conservation initiatives in the near future
