PSGB Spring Meeting 2003
Thursday 10th and Friday 11th April
School of Psychology, University of St Andrews, Fife
The Spring meeting aims to encourage postgraduate students to give short presentations at a national conference and to provide students with the opportunity to meet leading primatologists. £25 prizes will be awarded for the best oral and poster presentations by postgraduate students.
Registration will take place on Wednesday (4-6pm) and on Thursday (8.30-9am). Talks will start at 9am on Thursday and finish mid-afternoon on Friday. Details of how to get to St Andrews are provided on the University website www.st-andrews.ac.uk and further details of travel and accomodation are available on www.saint-andrews.co.uk, www.visitscotland.net and www.standrews.com/fife. Unfortunately, student dorms are not available in St Andrews at the time of the meeting - places may be available in the St Andrews youth hostel (01334 479911). St. Andrews has a number of attractions, including a castle and cathedral, botanic gardens, beaches, coastal walks, golf courses, restaurants and pubs, and the nearby Isle of May, famous for its seabird colonies and grey seals, is accessible by boat trip (see www.visit-standrews.co.uk or contact the St. Andrews Tourist Office 01334 472021).
Registration fees for the meeting (payable on the door) are £7 for non-student PSGB members, £5 for postgraduate student members, £3 for undergraduate student members, and £10 for non-members.
To obtain further information, e-mail Dr Gillian Brown (grb4@st-andrews.ac.uk) or Dr Klaus Zuberbuhler (kz3@st-andrews.ac.uk).
Programme
Thursday 10th April
8.30 - 9.00 REGISTRATION
9.00 - 9.10 WELCOME ADDRESS
9.10 - 9.40 ANDREW WHITEN 'Cultural Panthropology'
9.40 - 10.10 CHARLES SNOWDON 'Social learning in cooperative breeders'
10.10 - 10.30 CHRISTINE CALDWELL 'Can scroungers be learners? Social learning in common marmosets, Callithrix jacchus'
10.30 - 10.50 YFKE VAN BERGEN 'Marmosets go back to school: the role of food sharing in learning about food'
10.50 - 11.20 TEA AND COFFEE / POSTERS
11.20 - 11.50 KEVIN LALAND 'Necessity is the mother of primate invention: an examination of behavioural innovation in primates'
11.50 - 12.10 SIMON READER 'Innovation, climatic variability, and brain evolution'
12.10 - 12.30 ANTONIO MOURA 'The cognitive abilities of Cebus apella libidinosus: tool use and survival in a harsh environment'
12.30 - 12.50 REBECCA HARRISON 'Can nonhuman ape limb preference be used in the study of the evolution of brain complexity?'
12.50 - 2.00 LUNCH BREAK / POSTERS
2.00 - 2.30 LOUISE BARRETT 'From 'what now?' to 'what if?': quotidian cognition and cognitive control'
2.30 - 2.50 GUILLERMINA ECHEVERRIA-LOZANO 'Reconciliation and post-conflict affiliation with former allies in chacma baboons (Papio cynocephalus)'
2.50 - 3.10 BONAVENTURA MAJOLO 'Post-conflict behaviour among Japanese macaque males'
3.10 - 3.30 FRIEDERIKE RANGE 'Recognition of third-party rank relationships in sooty mangabeys (Cercocebus torquatus atys)'
3.30 - 3.50 EMILY BETHELL 'Rank effects on chimpanzee social monitoring'
3.50 - 4.20 TEA AND COFFEE / POSTERS
4.20 - 4.50 DEBORAH CUSTANCE 'Testing for stimulus enhancement, emulation and imitation in pig-tail macaques (Macaca nemestrina), gorillas (Gorilla gorilla), orang-utans (Pongo pygmaeus) and human children'
4.50 - 5.10 VICTORIA HORNER 'Is chimpanzees social learning affected by observing errors?'
5.10 - 5.30 SARAH MARSHALL-PESCINI 'Social learning of nut-cracking behaviour in infant and juvenile chimpanzees (Pan troglodytes)'
Friday 11th April
9.00 - 9.30 HANNAH BUCHANAN-SMITH 'Colour vision and cognition in primates'
9.30 - 9.50 NICK BLACKWOOD 'Do age and sex affect responsiveness to novelty in common marmosets?'
9.50 - 10.10 PAUL ASHLEY 'Behavioural and physiological methods for the assessment of social status in pair housed common marmosets (Callithrix jacchus)'
10.10 - 10.30 ELIZABETH PIMLEY 'Ranging patterns and social interactions of Allen's bushbabies (Galago alleni cameronensis) in Cameroon'
10.30 - 10.50 TOGU SIMORANGKIR 'The impact of offspring on the feeding and social behaviour of wild female orangutans (Pongo pygmaeus)'
10.50 - 11.20 TEA AND COFFEE / POSTERS
11.20 - 11.40 KIRSTEN PULLEN 'Enclosure use and dyadic interactions of a bachelor group of western lowland gorillas (Gorilla gorilla gorilla)'
11.40 - 12.00 SANDRA TRANQUILLI 'Semantic content in black-and-white colobus (Colobus polykomos) vocal communication'
12.00 - 12.20 HUGO RAINEY 'Hornbills can distinguish between alarm calls of Diana monkeys'
12.20 - 12.40 KATJA LIEBAL 'Chimpanzee gesture sequences'
12.40 - 1.00 BRIDGET WALLER 'Differential behavioural effects of 'smiling' and 'laughing' in chimpanzees (Pan troglodytes)'
1.00 - 1.05 CLOSING ADDRESS AND AWARD OF PRIZES
Abstracts for oral presentations
Behavioural and physiological methods for the assessment of social status in pair housed common marmosets (Callithrix jacchus)
ASHLEY P.J.(1), NEILL J.C.(1), MIDDLEMISS D.N.(2) AND HENDRIE C.A.(3)
(1) Bradford School of Pharmacy, University of Bradford, BD7 1DP
(2) Glaxo SmithKline Pharmaceutical Co, Harlow, Essex
(3) Department of Psychology, University of Leeds, Leeds
In the wild, common marmoset groups usually consist of a dominant breeding pair and several generations of offspring. Non-breeding adult members of the group are reproductively suppressed by the dominant pair. Dominance is therefore the single most important factor controlling an individual's ability to reproduce. Cortisol (the major "end product" of HPA axis activation) has been used as an objective marker of stress in primates (Bahr et al. 2000, General and Comparative Endocrinology, 117,3, 427-438). In stable primate hierarchies dominant individuals frequently have lower basal concentrations of cortisol than subordinates (Sapolsky 1982, Hormones and Behavior, 16, 3, 279-292). However this relatively simplistic model does not fully explain some of the observations seen in primates. The common marmoset exhibits pronounced social regulation of HPA function (Saltzman et al. 2000, Psychoneuroendocrinology, 25, 5, 463-477). However it remains to be determined how social status and its physiological consequences relate to the situation often seen in research environments (e.g. where animals are pair housed with multiple pairs in one room). Indeed little attention has been paid to the impact of such environmental constraints on behaviour (and physiology), which is surprising given the importance of social status on such parameters. The current study therefore aims to produce a behavioural and physiological description of status in pair housed marmosets. We report here on the behavioural methods developed to identify and characterise social status and to correlate social status to cortisol levels.
From "what now" to "what if": quotidian cognition and cognitive control
LOUISE BARRETT
School of Biological Sciences, University of Liverpool
What is the difference between monkeys and apes? As with most questions of this nature, it all depends on who you ask, and there is, as yet, no definitive answer. Here, it is suggested that understanding how monkeys and apes differ lies in the evolution of a more dispersed social system among the apes, and a consequent need for greater cognitive control over both behaviour and mental processes. In such dispersed systems, individuals must, in some sense, be able to mentally represent individuals that are not present and to retain and manipulate information about them, whereas there is no such pressure for these abilities to evolve in spatially and temporally stable monkey groups. Via a process of analogical reasoning (something of which apes, but not monkeys, appear to be capable), this ability to represent others in alternative spatial locations provided a scaffold for the development of an extended sense of future time in the hominoids. Improved cerebellar-neocortical circuits would have been crucial for the construction and modulation of the neural maps needed to create these inner cues and allow animals to represent social relationships internally in the absence of the individuals concerned. The anterior cingulate cortex (ACC), in particular, is suggested to be crucial in this respect; a notion supported by the fact that "spindle cells", a particular class of neuron in the ACC, are found only in apes and humans, and not monkeys. Consequently, studies directed at testing analogical reasoning ability and aspects of executive function, like inhibition, attention-to-action and planning, may help reveal exactly how apes and monkeys differ cognitively from each other.
Rank effects on chimpanzee social monitoring
EMILY BETHELL
Department of Psychology, University of Portsmouth
Visual monitoring of conspecifics provides many social animals with the information necessary to interact with group members in an optimal way. Dominance hierarchies are an organising force in most primate societies. In the chimpanzee (Pan troglodytes) the nature of social interactions between individuals and access to resources are dictated by the relative dominance status of each animal. We would therefore expect attention structures to vary between chimpanzees of different rank. It was hypothesised that high ranking chimpanzees should allocate a significant proportion of time attending to reproductive strategies. Lower ranking animals, however, constrained by the risk of attack from dominants, would be expected to allocate a greater proportion of their time towards monitoring the position and behaviour of those dominants in order to avoid such attacks. Analysis of data collected at the Budongo Forest Project, Uganda, revealed rank-determined attention structures for both males and females. In particular, the results highlighted the unique implications of alpha status for both males and females with respect to following reproductive strategies.
Do age and sex affect responsiveness to novelty in common marmosets?
NICK BLACKWOOD(1), PETER PEARCE(2), LEAH SCOTT(2) AND JAN DERUITER(1)
(1) Evolutionary Anthropology Research Group, Department of Anthropology, University of Durham, 43 Old Elvet, Durham, DH1 3HN
(2) Biomedical Sciences Department, Dstl, Porton Down, Salisbury, SP4 0QJ
Sex differences in callitrichids is an area of research receiving increasing attention, as evident from the symposium at the recent IPS meeting in China. The effect of gender and age are important factors to consider when studying behavioural variation across individuals. We studied responsiveness to novel objects in common marmosets (Callithrix jacchus). It is expected that males in general take greater risks, as they have higher variation in their reproductive success compared to females (Bateman's Rule). In terms of novelty responsiveness this would predict that males should be more inclined to investigate novel objects or situations. With respect to age, we expected younger animals to be more novelty responsive; in relation to the importance of learning at this stage of their life history, they would be more inquisitive. We presented nine novel stimuli to temporarily isolated female (n=42) and male (n=26) marmosets in a home cage environment. We scored all individuals for visual attendance, latency to first approach, latency to first contact, duration of proximity and duration of contact. We did not find a consistent effect of age or sex on these scores. This allows us to investigate individual variation without detrimental effect on analyses from these confounding variables. The implications of the results for investigating behavioural traits will be discussed.
Colour vision and cognition in primates
HANNAH M. BUCHANAN-SMITH(1), ANDREW C. SMITH(1), ALISON K. SURRIDGE(2), MARK J. PRESCOTT(3), DANIEL OSOSIO(4) AND NICHOLAS I. MUNDY(5)
(1) Scottish Primate Research Group, Department of Psychology, University of Stirling, Stirling, FK9 4LA
(2) School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ
(3) Research Animals Department, RSPCA, Horsham, West Sussex, RH13 9RS
(4) Department of Biological Sciences, University of Sussex, Falmer, Brighton, BN1 9QG
(5) Department of Zoology, Downing St, University of Cambridge, Cambridge CB2 3EJ
An animal's sensory capacities will affect its cognitive abilities, such that its ability to see, smell, taste, touch and hear stimuli will determine how it interacts with its social and physical environment. Primates are excellent models to examine the utility of colour vision, and its effects on cognitive abilities, as not only within the order are there routinely monochromatic, dichromatic and trichromatic species, but there is also variation within most species of New World, and some species of Madagascan primates. This colour vision polymorphism means that all males and some females are dichromatic, whilst other females are trichromatic. In this paper we explore the effects that this may have on the behaviour of these primates. Field observations and controlled experiments on tamarins (Saguinus spp.) indicate that on certain tasks, colour vision affects foraging behaviour, efficiency and learning abilities.
Can scroungers be learners? Social learning in common marmosets, Callithrix jacchus
CHRISTINE CALDWELL(1) AND ANDREW WHITEN(2)
(1) School of Psychology, University of Exeter
(2) School of Psychology, University of St Andrews
Previous research concerning the relationship between scrounging and social learning has generally shown scrounging to have an inhibiting effect on learning. We report data in which common marmoset subjects that could interact with, and scrounge food rewards from, a trained demonstrator, learned a task much more effectively than those that received a purely observational demonstration (through wire mesh). Fifty-nine common marmoset subjects were divided into five groups which were provided with differing pre-test experience. The five conditions were: observation of a trained demonstrator through wire mesh (O); joint interaction with a trained demonstrator allowing the possibility of scrounging (S); individual interaction with the apparatus (I); joint interaction with another naïve individual (J); and no prior experience (control, C). Significantly more individuals from the scrounging group learned the new behaviour, compared with the other four groups. We propose that there are several reasons that our result contrasts with those described in the previous literature, including the nature of the task we used, and the social structure of the species that we tested. We suggest that the inhibitory effect of scrounging on social learning may have been over-emphasised in the past, and that there may be situations under which scrounging is likely to facilitate learning.
Testing for stimulus enhancement, emulation and imitation in pig-tail macaques (Macaca nemestrina), gorillas (Gorilla gorilla), orang-utans (Pongo pygmaeus) and human children
DEBORAH CUSTANCE
Department of Psychology, Goldsmiths College, Lewisham Way, New Cross, London, SE14 6NW
Several sources of information are potentially available to an observer when s/he is exposed to a model. A series of experiments were conducted to explore three kinds of social learning: stimulus enhancement (observers focus their manipulations upon the same part of an object as a model), emulation (observers cause a part of the object to move in the same direction as a model) and imitation (observers learn to use the same physical actions from a model). Four puzzle boxes were presented to 12 pig-tailed macaques and 10 two- to three-year-old children. The boxes were designed to test for stimulus enhancement and emulation. The monkeys only produced only fragile evidence of emulation on one box, while the children provided clear evidence of social learning on all four boxes. A conspecific demonstrator was then used to show two groups of monkeys alternative methods for opening an artificial fruit. No evidence of precise behavioural matching was found. 11 gorillas and 10 orangutans were shown a button that could be pounded or turned with the flat of the hand to produce a food reward. The button was obscured by the human model's hand so that any matching would be based on reproducing the model's actions rather the movement of the button. There was evidence of matching by the orang-utans but not the gorillas. While the human children utilised and faithfully reproduced several aspects of a model's actions, the monkeys and great apes did so to a much lesser extent.
Reconciliation and post-conflict affiliation with former allies in chacma baboons (Papio cynocephalus)
GUILLERMINA ECHEVERRIA-LOZANO AND LOUISE BARRETT
Evolutionary Psychology and Behavioural Ecology Research Group, School of Biological Sciences, University of Liverpool, Liverpool, L69 7ZB
Since the first observation of post-conflict affiliative contact between former opponents in captive chimpanzees, in 1979 (de Waal and Roosmalen), a productive area of research in conflict management was open. Since this first study, several studies have been conducted on a number of primate and non-primate species such as long tailed macaques, vervet monkeys, baboons, ring-tailed and red-fronted lemurs, patas monkeys, gorillas and spotted hyenas. However, the research on post-conflict interactions has been mainly focused in the study of reconciliation (post-conflict affiliative behaviour between former opponents), and only a few studies have considered other post-conflict interactions between the aggressor or the victim and other members of the group. To our knowledge, only one has evaluated the possible function that these interactions may have. Data were collected from one of the two main study troops of chacma baboons (Papio cynocephalus) in the De Hoop Nature Reserve, Western Cape Province, South Africa between March 2001 and August 2002. The results showed focus on 1) reconciliation and 2) post-conflict interaction between the victim/aggressor and their former allies. We evaluate the possible function of them both and compare them as different strategies of conflict management.
Can nonhuman ape limb preference be used in the study of the evolution of brain complexity?
REBECCA M. HARRISON
Department of Archaeology, University of Sheffield
Preferential limb use appears to be associated with the increased complexity and compartmentalisation of the brain which in turn has been correlated with the development of language and cognition. Thus limb preferences in apes are widely studied in order to further our understanding of when the species-level right limb preference found in modern humans evolved. Consequently studying limb preference has become considered a means, albeit indirect, to approach such topics as the evolution of cognition. Even though there is some intraspecific variability, which is least expressed for complex tasks and more expressed for less demanding tasks, modern humans display a species-level right limb preference. When seeking an evolutionary trajectory for this species-level right limb preference in humans, studies of limb preference in extant African nonhuman apes have produced contradictory results: some population preferences have been displayed but there is no convincing evidence of a species-level limb preference in bonobos, chimpanzees or gorillas. The question remains as to whether these patterns of behavioural laterality can be used as a measure of inferring cognitive ability. Structural asymmetries have been discovered in nonhuman ape brains in areas that in humans are associated with language, cognition and motor activity. Together this suggests that using species-level limb preference to infer cognition might be too great a leap. Intraspecific variability in limb preference should be examined more closely in nonhuman and human apes, and this should be done in the context of species brain asymmetry. Using limb preference alone to infer cognition may produce misleading results.
Is chimpanzees social learning affected by observing errors?
VICTORIA HORNER
School of Psychology, University of St Andrews
Many of the natural tool-using activities of chimpanzees, such as termite fishing or nut-cracking involve a complex mixture of interconnecting causal relationships, and many of these behaviours are thought to be acquired by social learning. The aim of this study was to determine whether chimpanzees are able to extract and utilize causal information by observation. If causal information does play a role in social learning, chimpanzees might benefit more from observing mistakes and successes than from only observing successes, as mistakes provide additional causal information about what not to do. However, this study found that there was no significant difference in the performance of subjects who observed both the incorrect and correct solution to a tool-using task, and subjects who observed only the solution. Therefore chimpanzees did not benefit from the observation of errors. However these subjects did perform significantly better than a stimulus enhancement control group, suggesting that the performance of the experimental groups was aided by observing the causal relevance of the tool. Two chimpanzees (one in each of the experimental groups) performed significantly better than would be expected by chance; but their success appears to be based on the formation of simple perceptual rules. However, subjects in the control group did not solve the task. Therefore the two successful subjects may have used the causal information available in the experimental demonstrations to form this set of rules. It therefore remains a possibility that chimpanzees can extract and utilize causal information by observation.
Necessity is the mother of primate invention: an examination of behavioural innovation in primates
KEVIN N. LALAND
Centre for Social Learning and Cognitive Evolution, School of Biology, University of St. Andrews, Fife, KY16 9TS
When learned behaviour patterns spread through animal populations, typically a single individual will have triggered the diffusion by devising a novel means of exploiting the environment. This capacity for "innovation" is important to the survival of many primates, of particular significance to endangered species forced to adjust to changing environments, and perhaps central to primate brain evolution. Quantitative analyses of reports of primate innovation suggest that innovators are disproportionately likely to be male, adult and of low social rank, and that this sex difference in innovation is found in (body size) dimorphic but not monomorphic species. Consistent with this, experimental studies of innovation in callitrichid monkeys reveal no sex differences in innovation. These observations can be accounted for in terms of the action of sexual selection.
Chimpanzee gesture sequences
KATJA LIEBAL, JOSEP CALL AND MICHAEL TOMASELLO
Max-Planck-Institute for Evolutionary Anthropology, Inselstrasse 22, D-04103 Leipzig, Germany
liebal@eva.mpg.de, call@eva.mpg.de and tomas@eva.mpg.de
The gestural communication of a group of 19 captive chimpanzees was observed, with particular attention to gesture combinations (sequences). The goal of the study was (1) to describe the inventory of gesture sequences with regard to the number and modalities of gestures combined and (2) to investigate whether chimps accommodate the gesture modality to the attention state of the recipient or even manipulate the recipient's state of attention by using particular gestures serving as attention-getter. The majority of combinations occurred in play context and were sequences of two or three gestures, which were most often repetitions of the same gesture. Other sequences combined gestures either within modality (visual, auditory, tactile) or across modalities. All combinations were used for functions that could also have been indicated with single gestures. Although chimpanzees used visually based gestures mostly when the recipient was already attending and tactile gestures regardless of whether the other's attentional state, they almost never used an attention-getter as the first gesture in a sequence - in order to secure attention - followed by a visual gesture. Instead of manipulating the recipient's state of attention other strategies were used to secure to be in the visual range of the recipient before performing visual gestures. Moreover, although the recipient frequently did not respond to the first gesture, the sender continued repeating the same gesture. Therefore chimpanzee gesture sequences don't seem to represent a strategy to increase the flexibility of the chimpanzee gestural repertoire, but seem to emerge by the recipient's lack of responsiveness.
Post-conflict behaviour among Japanese macaque males
BONAVENTURA MAJOLO(1), RAFFAELLA VENTURA(2) AND NICOLA KOYAMA(1)
(1) School of Biological and Earth Sciences, Liverpool John Moores University, Byrom St., Liverpool, L3 3AF
(2) Scottish Primate Research Group, School of Social and Health Sciences - Division of Psychology, University of Abertay Dundee, 158 Marketgait, Dundee, DD1 1NJ
Since it was first defined by de Waal & van Roosmalen (1979), reconciliation (defined as the post-conflict friendly reunion of former opponents that restores their social relationship) has been reported to occur in many social primates and other mammals. Reconciliation is more often observed among kin and/or among animals that maintain long-lasting good relationships with one another. For this reason, most of the studies conducted so far have been focused on cercopithecine females who are philopatric and show complex social interactions. However, almost no data are available on reconciliation among males living in multimale/multifemale groups, although they may gain some benefits by establishing good relationships with one another (e.g. tolerance in the group) and thus by restoring these relationships through post-conflict affiliation. This study focuses on post-conflict behaviour among wild non-provisioned Japanese macaque (Macaca fuscata yakui) males. Reconciliation was observed to occur in 27% of the conflicts among males. This figure is high even if one compares it to the frequency of reconciliation recorded among Japanese macaque females in other studies. This result is discussed in light of the high frequency of grooming observed among Yakushima males in comparison to those living on the mainland (Macaca fuscata fuscata) and for the consequences that reconciliation may have on male reproductive tactics and group transfers.
Social learning of nut-cracking behaviour in infant and juvenile chimpanzees (Pan troglodytes)
SARAH MARSHALL-PESCINI AND ANDREW WHITEN
Scottish Primate Research Group, School of Psychology, University of St. Andrews, St. Andrews, KY16 9JU
sarahmarshallpescini@hotmail.com
Nut cracking varies between communities of wild chimpanzees both in its occurrence and in the material tools used in ways that suggest it is an example of "cultural" behaviour. Detailed study of the acquisition of nut cracking in wild chimpanzees is consistent with this conclusion. However only one experiment has been carried out in captivity explicitly to test the role of social transmission in the acquisition of this behaviour, in adult chimpanszees. The study presented here is the first to investigate the effect of age and knowledgeable conspecific and human models on infant and juvenile chimpanzees" acquisition of nut cracking. Results confirmed that nut cracking can be acquired by social learning but only in chimpanzees 3 to 4 years old and above. Direct comparisons are made with a developmental study carried out with wild chimpanzees, revealing striking similarities in developmental profiles.
The cognitive abilities of Cebus apella libidinosus: tool use and survival in a harsh environment
ANTONIO C. DE A. MOURA AND PHYLLIS C. LEE
Department of Biological Anthropology, University of Cambridge, Downing Street, Cambridge, CB2 3DZ
Among Neotropical Primates, capuchin monkeys have the largest brain size in relation to body mass and show great cognitive capabilities in solving problems and in tool use. Despite the huge amount of data on tool use in captive groups of Cebus spp., in wild groups tool use seems to be quite rare. A group of C. apella libidinosus was followed for one year at the Serra da Capivara National Park, located in the dry Caatinga forest of Southeast Piaui, Brazil. In this area, droughts are frequent and the dry season lasts 6 months. The monkeys presented a strikingly rich repertoire of tool use for obtaining food. They used stones to help dig for tubers, to crack open dry branches, cactus, seeds and dry Manihot tubers. The monkeys also used branches for probing into tree holes and rock crevices and on many occasions the branch (twig) was modified by removing leaves or stems. A total of 134 cases of tool use were recorded, during the 311.5 hours of sampling observation. In the harsh condition of the Caatinga, ecological pressure maybe the primary factor driving the cognitive capabilities of Cebus and the use of tools is a crucial component of their foraging and energetic strategy. Effectively, the monkeys are maximising their energetic intake through their cognitive capabilities. The use of a stone to pound the ground is a remarkable type of tool use not yet described for any population of Cebus either in captivity or wild.
Ranging patterns and social interactions of Allen's bushbabies (Galago alleni cameronensis) in Cameroon
ELIZABETH PIMLEY
Sub-Department of Animal Behaviour, University of Cambridge, Madingley, Cambridge, CB3 8AA
Allen's bushbabies (Galago alleni cameronensis) are small nocturnal prosimians inhabiting the rainforests of equatorial Africa. This paper presents new information on the social organization of these lesser-studied primates, derived from fieldwork in Cameroon using radio-telemetry combined with behavioural observations. Allen's bushbabies were found to be more sociable than expected for supposedly solitary primates, spending 25% of observations in proximity to a conspecific. Female Allen's bushbabies tended to form sleeping groups and possessed highly overlapping ranges that were overlapped by one male. The relatively low testes volumes of males in combination with ranging data imply that Allen's bushbabies in Cameroon adopt a polygynous mating system. In Cameroon the social behaviour and ranging patterns of Allen's bushbabies appear to conform to a dispersed unimale-multifemale(harem) social system. Such dispersed social systems differ from conventional gregarious social arrangements, in that individuals forage solitarily rather than together. In this respect the social organization of Galago alleni cameronensis resembles a dispersed neighbourhood, where a network of social relationships exists between individuals.
Enclosure use and dyadic interactions of a bachelor group of western lowland gorillas (Gorilla gorilla gorilla)
KIRSTEN PULLEN
Exeter University and Paignton Zoo Environmental Park
The establishment of a bachelor group of western lowland gorillas at Paignton Zoo Environmental Park, Devon, consisting of one silverback, three blackbacks and one sub-adult, has provided the opportunity for longitudinal research into the social behaviour of gorillas in a bachelor group situation. Captive bachelor groups have been established to deal with the surplus of males in the captive breeding programme, based on observations of bachelor groups of wild mountain gorillas. However the presence of bachelor western lowland gorillas groups in the wild is still disputed. Thus long-term research on the effects of this husbandry technique may have wide implications for the welfare of captive male gorillas. Observations of the group (five male gorillas) at Paignton Zoo were carried out over a period of nine days, using instantaneous scan sampling, to assess their enclosure use and the dyadic interactions within the group. Due to considerations of the captive breeding programme, one blackback male was then removed from the group. The observation schedule was therefore repeated for a further nine days to assess the effect of the removal of this male on the enclosure use and dyadic interactions of the remaining four males. A spread of participation index (spi) was constructed for each animal, both prior to and since the removal of the blackback male, to assess levels of enclosure use in both situations. In addition, the results of the dyadic interactions were analysed to provide an insight into male / male interactions exhibited within a bachelor group. The implications of these results will be discussed here.
Recognition of third-party rank relationships in sooty mangabeys (Cercocebus torquatus atys)
FRIEDERIKE RANGE
Department of Psychology, University of Pennsylvania , U.S.A.
Several experimental and observational studies demonstrate "triadic knowledge": an individual knows about the relationship that exists between two others (e.g. Cheney and Seyfarth 1990, 1999; Silk 1992, 1999). Although it has been argued that primates differ from most other mammalian species in their ability to understand third-party social relationships (e.g. Harcourt 1992), more tests are required using non-primate animals (e.g. Connor et al. 2000). Additionally, most studies on the social intelligence of non-human primates in their natural environment have focused on vervets and baboons (e.g Cheney et al. 1996), species that live in savannah habitat. We know little about cognitive abilities of species living in tropical forests, a habitat that may have placed different demands on the primate brain; whereas in savannah habitat most interactions between others can be observed, low visibility makes this impossible in forest habitat. I present the first data on knowledge of triadic relationships a rainforest primate, the sooty mangabey. Using focal animal and ad libitum sampling on a group of approximately 120 individuals, I examined the relative ranks of an individual's opponent and the animal recruited as an ally during conflicts. I found that even young animals enlisted agonistic support most often from animals higher ranking than their opponents, thus indicating knowledge of third-party rank relationships. Further, I examined the relative rank among individuals competing for access to grooming partners. When a high-ranking animal approached two lower ranking animals and supplanted one, it was the lower ranking individual who was more likely to move away.
Innovation, climatic variability, and brain evolution
SIMON M. READER
Utrecht University, Behavioural Biology, Padualaan 14, PO Box 80086, 3508 TB Utrecht, The Netherlands
Behavioural innovation, new or modified learned behaviour, provides an ecologically relevant measure of cognitive ability. Innovation rate can be operationally measured as the frequency of published reports of novel behaviour, and thus provides a useful tool to quantify inter-taxon differences in cognition and to test classic hypotheses regarding the evolution of the brain. Here, I show that brain size and a cognitive capacity are correlated. A comparative analysis of 533 instances of non-human primate innovation established that innovation frequencies are positively correlated with species" relative neocortex volumes, after controlling for phylogeny and research effort. Moreover, innovation frequencies correlate positively with other cognitive measures, such as measures of individual learning, social learning, and tool use. These findings parallel similar results in birds, suggesting a striking pattern of convergent evolution in two taxa whose ancestors diverged more than 300 million years ago. Primates" innovation frequencies were not found to correlate with measures of climatic variability or with species" range size, perhaps inconsistent with the hypotheses that more innovative species can tolerate greater climatic variability, that innovation is a response to climatic change, or that climatic variability has selected for a propensity to innovate.
The impact of offspring on the feeding and social behaviour of wild female orangutans (Pongo pygmaeus)
TOGU SIMORANGKIR
Oxford Brookes University and Yayasan Orangutan Indonesia/YAYORIN (Orangutan Foundation Indonesia)
Orangutans (Pongo pygmaeus) are known to be essentially solitary animals, although occasionally they do occur in groups and may even form travel-bands that stay together for several days. Mothers and offspring are the only consistent social units in orangutans. The offspring is totally dependent on the mother, which consequently affects the mother's daily activities. The young orangutan remains dependent for about 6 years. This research investigates the influence of the offspring, based on their age-class, on the mother's behaviour, with a focus on feeding and the social behaviour. Records of feeding include time required to reach, process, extract, grip, chew and swallow each food source. Measures of social behaviour include grooming, mating, childcare, breast-feeding and vocalisation. The research is based on a six months preliminary study at the Camp Leakey, Tanjung Puting National Park, Central Kalimantan, Indonesia. The observations were made during the period of food source scarcity, between February and August 1998. The research method is "focal animal instantaneous sampling", with data collection at one minute intervals. The study subjects were three orangutan females with offspring at different ages and an orangutan female without offspring as a baseline for comparison. The females were named: A with a 2 years old offspring, B with a 6 year old offspring, C with 10 years old offspring and D without offspring. The research concluded that, in terms of feeding behaviour, there were no significant differences between A, B and C, the only difference in feeding behaviour was with D, who spent significantly less time on this activity. The food consumed during this period of food scarcity was mainly bark and leaves. On the other hand, in terms of social behaviour, Female A, with the youngest offspring, was different from B and C. She spent significantly more time breast-feeding, whilst B and C spent their time in vocalisation and occasionally grooming the offspring and female D spent time on mating.
Social learning in cooperative breeders
CHARLES T. SNOWDON
Department of Psychology, University of Wisconsin, Madison, U.S.A.
Coordination of infant care among cooperatively breeding tamarins and marmosets requires close attention to the behavior of other group members and responsiveness to cues produced by others. Does this coordination of activities required by cooperative infant care translate into increased skills in social learning and changes in brain activity? In the first part I present three studies where cotton-top tamarins display social learning skills rarely seen in other, non-cooperative breeding monkeys. (1) Tamarins learn socially to avoid highly preferred familiar foods made noxious by the addition of invisible white pepper. The tamarins that sampled the food produced visual reactions of disgust and alarm calls, providing a communication mechanism to keep others away. (2) Tamarins more readily learned a novel foraging task requiring a novel motor pattern in the presence of their mate as demonstrator than when alone. Social learners explored the apparatus and acquired the motor response significantly faster than individual learners. However, they did not receive food rewards any sooner because they followed closely behind the demonstrator, rather than foraging independently. (3) Tamarins each learned to pull on a tray that released a food reward. When the trays were adjusted so that food could be obtained only if both monkeys pulled simultaneously, they rapidly and spontaneously acquired the cooperation task. Tamarins rarely pulled on the tray when alone, compared to when both partners were present. These studies demonstrate a high level of social learning in tamarins. In the second part I present results using functional magnetic resonance imaging (fMRI) to study neural responses of common marmosets to olfactory cues from ovulating and non-ovulating females. Males conditioned to expect to copulate with a female in the presence of a previously neutral lemon odor displayed increased neural activation in the same areas activated by odors of ovulating females. (Supported by MH29775, MH 58700)
Semantic content in black-and-white colobus (Colobus polykomos) vocal communication
KLAUS ZUBERBUHLER(1,3) AND SANDRA TRANQUILLI(2,3)
(1) School of Psychology, University of St Andrews, St Andrews, U.K.
(2) Dipartimento di Biologia Animale e dell"Uomo - Universita" degli Studi di Roma "La Sapienza", Rome, Italy
(3) Centre Suisse de Recherches Scientifiques, Tai Monkey Project, Abidjan, Ivory Coast
In the Tai forest, Ivory Coast, western black-and-white colobus (Colobus polykomos polykomos) are preyed upon by both leopards (Panthera pardus) and crowned-hawk eagles (Stephanetus coronatus). Field playback experiments conducted on many black-and-white colobus groups show that, in response to the two predator vocalizations and to the alarm calls to eagle and to leopard of Diana monkeys (Cercopithecus diana), Campbell's monkey (Cercopithecus campbelli) and chimpanzee (Pan troglodytes), they give acoustically and structurally distinct alarm calls, according to the different predator. The results of these experiments are consistent with the hypothesis that the black-and-white colobus are able to represent mentally and acoustically the type of danger related to the type of predator. This represents a first hint of a semantic structure in their vocal communication.
Marmosets go back to school: the role of food sharing in learning about food
YFKE VAN BERGEN(1), ROSAMUNDE ALMOND(1) AND GILLIAN R. BROWN(2)
(1) Sub-Department of Animal Behaviour, University of Cambridge
(2) School of Psychology, University of St. Andrews
Many species actively provision their offspring with solid food. One function of this behaviour may be to ensure that the young are provided with essential nutrients before they can obtain these for themselves. It may also give infants the opportunity to learn which foods are palatable. This study examined social influences on foraging behaviour in the common marmoset (Callithrix jacchus). A series of experiments investigated the influence of sharing novel food with family members on the diet choice of infant marmosets. Infants preferred a novel food that they had shared with family members to a novel food that they had experienced alone. Older infants may even prefer a novel food they have only watched their parents eat. Further experiments tested the relative effects of palatability, accessibility and novelty on infant food sharing behaviour. Parents refused to share palatable novel foods more often than familiar foods, but quickly handed over unpalatable novel foods. Infants were equally likely to beg for familiar and novel foods that they could not reach. When food was accessible to them, infants readily ate familiar foods but relied more on sharing when food was novel. The results of this study support the hypothesis that sharing novel food with family members enables infants to gain information about new foods and incorporate these foods into their diets, but, at least in this study, parents do not play an active role in the learning process.
Differential behavioural effects of "smiling" and "laughing" in chimpanzees (Pan troglodytes)
BRIDGET M. WALLER
Department of Psychology, King Henry Building, University of Portsmouth, Portsmouth, PO1 2DY
Primate non-vocal communication has to date been understudied, and the social function of facial displays is largely unknown. This study examines the behavioural consequences of the Silent Bared Teeth display (SBT, "fear grin") and the Relaxed Open Mouth display (ROM, "playface") in the chimpanzee. Rates of affinitive behaviour increase (in relation to baseline levels) following SBT, suggesting that SBT is a signal of affinity. ROM is observed primarily during play, and dyadic play bouts are significantly longer when ROM is bidirectional, indicating that it is an effective signal of play. It is also found that rates of affinitive behaviour increase after ROM, suggesting that ROM may have a social bonding effect. These findings support the hypothesis that human smiling and laughing are rooted in different motivational complexes, but have since converged in the course of evolution (van Hooff, 1972).
Cultural Panthropology
ANDREW WHITEN, VICTORIA HORNER AND SARAH MARSHALL-PESCINI
Centre for Social Learning and Cognitive Evolution [ http://culture.st-and.ac.uk/SoLaCE ]
and Scottish Primate Research Group, School of Psychology, University of St Andrews, St Andrews, KY16 9JU
"Culture" - in the most basic sense of "tradition" - has been shown to exist in many species, including fish, birds and mammals. There is much more to the phenomenon of culture in humans, however, than the mere existence of traditions. From these two contrasting observations, it follows that rather than expecting that culture can be assigned to living or ancestral species in an all-or-none fashion, reconstruction of the evolution of this uniquely complex phenomenon is likely to depend on successfully teasing apart its components, which may have evolved in a somewhat mosaic fashion. In this paper ten such aspects of human culture are distinguished, and evidence is offered that most of them are manifested in chimpanzees, even if sometimes in minimal form. This permits us inferences about the cultural profile of our common ancestor. The aspects of culture examined include large scale patterns of behavioural variation across populations, the mechanisms available for social transmission, and the behavioural contents of traditions. The contrasts so drawn for humans and chimpanzees offer a framework for cultural comparisons between other taxa from the past and present.
Reference: A. Whiten, V. Horner, & S. Marshall-Pescini. "Cultural Panthropology" Evolutionary Anthropology, Special Issue on Cultural Evolution. in press March/April 2003.
Abstracts for posters
Relating the use of height and space to the acquisition of planning behaviour: a comparative study of captive and wild western lowland gorillas (Gorilla gorilla gorilla)
MARIE BAMBURY
Department of Archaeology, Bristol University
The aim of this thesis is to demonstrate that the evolution of self-awareness can be investigated through the study of planning and problem-solving skills displayed by captive western lowland gorillas whilst moving at height. This work has been based on theories developed by Povinelli and Cant (1995) suggesting that orang-utans display patterns of behaviour during climbing activity that could be considered as evidence for self-awareness. Research carried out for this thesis at Howlett's Wild Animal Park, Paignton Zoo, San Diego Zoo and San Diego Wild Animal Park suggests that there are four social and two ecological motivators for clambering activity. The social motivators include displaying social status to other group members and the human audience, ensuring group safety, hiding and exploring. The ecological motivators are feeding and resting. During these activities an element of planning prior to clambering activity and a corresponding element of problem solving can be distinguished in most instances. Some of the planning and problem-solving behaviour is common to all the gorilla groups studied however, certain types of behaviour are unique to an individual group and can be demonstrated to be a result of social rather than environmental pressures. This work has produced compelling evidence to suggest that captive western lowland gorillas are not only capable of planning and problem-solving abilities, but can also accurately assess and exploit the mental states of other individuals within the group.
Olfactory communication in white-fronted brown lemurs (Eulemur fulvus albifrons)
VICTORIA COOPER
Psychology & Life Sciences, Bolton Institute, Deane Road, Bolton, BL3 5AB
It is well documented that strepsirrhine primates rely greatly on olfactory cues in their environment, in contrast to visual cues and in comparison with many haplorrhine primates. In this study, data were collected over a year from a family group of six E.f. albifrons, revealing the frequency and location of olfactory behaviours, as part of an ongoing study testing the role of colour in sexual selection and communication in E. fulvus subspecies. The olfactory behaviours observed included sniffing, licking, and scent-marking. Preliminary analysis revealed that as well as directing olfactory behaviours to objects in their environment, the lemurs also directed olfactory behaviours to different locations on another lemur's body, in varying proportions. There were significant differences between males and females with regards to the frequency of sniffing and licking of another female lemur's anogenital region. The results are discussed in relation to the role of olfaction in inter-sexual behaviour in E.f. albifrons.
Quantity or quality? Comparing reproductive parameters in captive bonobos (Pan paniscus) and chimpanzees (Pan troglodytes)
MIEKE DE LATHOUWERS(1,2) AND LINDA VAN ELSACKER(1,2)
(1) University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
(2) Centre for Research and Conservation - Royal Zoological Society of Antwerp. Koningin Astridplein 26, B-2018 Antwerp, Belgium
Bonobo (Pan paniscus) females can co-operatively dominate males and monopolise resources whereas chimpanzee (Pan troglodytes) females in general are controlled by their male conspecifics. If control over resources leads to an immediate higher reproductive output bonobo females might ultimately have a greater reproductive success than chimpanzees. Our aim is to test this hypothesis by comparatively investigating reproductive parameters in captive bonobos and chimpanzees. We calculated the age at first birth, fertility rate, infant survival and interbirth interval. Our results show that bonobo females tend to reproduce at a younger age and have higher infant survival. However, they have a lower fertility rate and a longer interbirth interval compared to chimpanzees. All these factors combined reveal that bonobo females do not have a higher reproductive success. However, bonobo and chimpanzee females apply different reproductive strategies to reach the same success. Where chimpanzees choose quantity to overcome high infant mortality, bonobos choose quality. We discuss whether the more central social role of females in bonobo society results in better control over infant survival as opposed to chimpanzees.
Spontaneous attention following: a comparative study in human adults and rhesus macaques
ERIKA N. LORINCZ, DAVID I. PERRETT AND JUAN-CARLOS GÓMEZ
School of Psychology, University of St. Andrews
Human infants progressively acquire the ability to follow attention displays by other humans, using increasingly complex body cues. Apes, monkeys and other animals also possess some capacity to attention follow. However the underlying mechanism that drives this behaviour is not fully understood either in humans or in non-humans. One suggestion is that attention following is a quasi-orienting reflex to automatically follow head direction of others. This idea is supported in humans by studies with Posner type paradigms, using drawings of head facing / looking at targets as priming cues. If the reflexive hypothesis is true, an individual's attention should initially be redirected "automatically" in the relevant direction. The aim of this study was to investigate the extent to which attention following was induced in 9 adult humans and 1 rhesus macaque. Eye movements were recorded with an eye tracker at the presentation of photographs of faces of conspecifics (humans or rhesus) and other species (orang-utans, lions, and cats) attending with congruent eyes and head direction either to a lateral empty space or to 1 of 2 lateral backgrounds. The analysis of the duration of inspections at locations lateral to the stimulus face shows that only 2 out of the 9 humans reliably follow attention in all conditions; the rest did not show any consistent gaze following pattern. The monkey subject showed a significant tendency to follow attention independent of the species only in the condition without lateral backgrounds. Our results suggest that attention following is not an automatic response.
Mating harassment in captive bonobos (Pan paniscus)
JEROEN STEVENS(1,2) HILDE VERVAECKE(1,2) AND LINDA VAN ELSACKER(1,2)
(1) University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
(2) Centre for Research and Conservation, Royal Zoological Society of Antwerp, Koningin Astridplein 26, B-2018 Antwerp, Belgium
Bonobos are known for their promiscuous and tolerant mating behaviour, which is considered to be an indication of low reproductive competition in this species. Previous studies from the wild and captivity have shown that mating harassment is rare. In an ongoing study on male mating strategies in captivity, data were gathered in three multi-male, multi-female groups at Apenheul (the Netherlands), Twycross (United Kingdom) and Planckendael (Belgium). We present data on quantity (number of cases by each individual) and quality (different behaviours: mild aggression, fierce aggression, approach, join sex) of mating harassment, defined as all interactions of third individuals with a copulating pair. We also investigate the effect of harassment on duration of copulation and test the hypothesis that, because of their high dominance positions, females can effectively interrupt copulations of group members. For males we propose that high-ranking males effectively interrupt copulations of lower-ranking males. In two study-groups, harassment by females was more common than harassment by males. We found that alpha males used mostly fierce aggression directed at lower ranking males, while aggressive mating harassment was rare amongst the lower ranking males. In alpha females, harassment was mostly of an affiliative nature, but at least in Twycross, lower ranking females used aggression frequently, suggesting female-female competition. The fact that mating harassment was most common in the study-group at Twycross, where bonobos were kept in a single room enclosure, suggests that potential for social plays an important role.
Influence of dominance rank, age and acute stress on cognitive performance in group-living long-tailed macaques
I.B. TOXOPEUS(1,2), E.H.M. STERCK(2), T.J. HEEREN(1), J.A.R.A.M. VAN HOOFF(2) AND B. M. SPRUIJT(3)
(1) Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, The Netherlands
(2) Department of Behavioural Biology, Utrecht University, The Netherlands
(3) Department of Animal and Society, Utrecht University, The Netherlands
Research on the effects of ageing on cognitive capacities has shown that there are considerable differences in the performance of aged individuals. Possible causes for this variability were found in their life history (humans) and long-term stress (humans and possibly macaques). Our hypothesis is that life-time stress facilitates age-related cognitive decline. The combined effects of chronic exposure to stress and ageing on the learning capacity were investigated with adult female long-tailed macaques, differing in age and dominance rank, by means of a 'Discrimination-Reversal' task. Previous results confirmed the hypothesis; however in this study we were confronted with a number of factors confounding the results, such as inter- and intra-individual differences in stress. In our view a better understanding of these factors is crucial for future social cognition research.
In situ conservation of Asian lorisines
PAMELA TRONI
Oxford Brookes University, Oxford
A paucity of information can be found on Asian lorisines; the IUCN 2002 presently classifies the conservation status of slow loris (Nycticebus coucang) as data deficient, the pygmy slow loris (Nycticebus pygmaeus) as vulnerable and the slender loris (Loris tardigradus tardigradus) as endangered. Fieldwork on the behavioural ecology of Asian lorisines has lagged behind that of the African taxa. This along with an increase in the commercial pet trade of lorises reinforces the necessity of further study into these little known nocturnal prosimians for conservation measures. Critical issues for loris conservation in habitat countries are related mainly to food and shelter. This study will build on long-term efforts by Schulze and Nekaris whose web sites have generated a number of requests about how to maintain lorises either bought or confiscated in the pet trade. The project will be conducted in two biodiversity hotspots and aims to focus on diet and habitat use of three different taxa of lorises. The goal will be to design and disseminate a manual to diet in situ translated into Vietnamese, Sinhala and Indonesian. Without encouraging the trade, the manual will address critical issues and problems such as obesity, weight loss, osteomalacia and death. The study will also incorporate an educational programme of local Sri Lankan children to raise awareness about lorisine behaviour and conservation issues.
Do spider monkeys have mental maps? A new procedure to study animal movements in the wild
ALEJANDRA VALERO AND RICHARD W. BYRNE
School of Psychology, University of St. Andrews, St. Andrews, KY16 9JU.
The spatial abilities of non-human primates when searching for or retrieving food have been widely documented. Experimental studies have shown that primates perform well at memorising the location of hidden food items, and have remarkable abilities to move about in least-distance paths. But wild primates may face even more demanding tasks than can be presented in a small-scale replica of their environment and so observational studies of primates" movements are also needed. We introduce Jupp's test, a novel way to analyse primate travel paths in the wild. We present a description of the procedure along with examples of its application to real data collected from observations of spider monkeys in a natural reserve in southeastern Mexico. In a real data example, we were able to pinpoint the extent of straight-line movements along one day's travel path. These were found to be in between stops the animal made at key feeding resources that could not have been in sight from each other, given the distances that separated them. Jupp's procedure is a powerful tool to test the hypothesis of primates" mental maps by studying animal movements in the wild instead of the animals" performance in captive conditions.
Pan continuity: bonobo-chimpanzee hybrids
HILDE VERVAECKE(1,2), JEROEN STEVENS(1,2) AND LINDA VAN ELSACKER(1,2)
(1) University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
(2) Centre for Research and Conservation, Royal Zoological Society of Antwerp, Koningin Astridplein 26, B-2018 Antwerp, Belgium
From historical accounts it appears that natural populations of bonobos and chimpanzees have been allopatric since their phylogenetic separation. There are no accounts of hybridisation under natural conditions. There is, however, evidence for interbreeding between bonobos and chimpanzees in captivity. We briefly (6.5 hrs) observed and filmed a small group of four bonobo-chimpanzee hybrids (2 males, aged 10 and 9, and 2 females aged 10 and 8). There was clear individual variation in degree of expression of typical chimpanzee - or bonobo features. In each individual there were anatomical features reminiscent of both of the parental species: the specific bonobo-like pink coloration of the lips, the hairstyle and slender body-built, the chimpanzee-like dorsal position of the female genitals, more sturdy body built and prognathism. The behaviours could be categorized less exclusively. We observed mostly female oriented interactions, including grooming, play, approaches and intersexual ventro-dorsal sex. There was one female coalition against the males. The individuals lip-smacked while grooming and performed swaggering displays. The hoots were like chimpanzee pant-hoots with an introduction, build-up and climax in a higher pitched bonobo tone and more "e" than "o" sounds. Studies on Pan in the seventies and eighties emphasised discontinuity between the two species, contrasting the male-dominated, aggressive nature of the chimpanzee to the female-oriented, peaceful nature of the bonobo. In the nineties and in present studies, the continuity among Pan is increasingly being documented. The existence of hybrids challenges our tendency for binary thinking and points at the conceptual relativity of the species gap.
Evidence from rhesus macaques (Macaca mulatta) suggests colouration may play a role in primate mate choice
CORRI WAITT(1), ANTHONY C. LITTLE(2), ANTHONY BROWN(3), HANNAH M. BUCHANAN-SMITH(1) AND DAVID I. PERRETT(2)
(1) Department of Psychology, University of Stirling, Stirling, FK9 4LA
(2) School of Psychology, University of St. Andrews, St. Andrews, Fife, KY16 9JU
(3) Harlan UK, Hillcrest, Dodgford lane, Belton, Leicestershire, LE12 9TE
Male animals of many species use conspicuous colouration to attract mates. Among mammals, primates possess the most brilliant secondary sexual colouration; however whether colour plays a role in female mate choice in primates remains unknown. In this study, we experimentally investigated whether male facial colouration is attractive to females in rhesus macaques (Macaca mulatta). In a captive setting, adult females were simultaneously presented with computer manipulated pale and red versions of male faces. Duration and direction of gaze were measured to establish visual preferences. Females exhibited strong preferences for the red versions of male faces. This is the first study to provide experimental evidence that male colouration may influence attractiveness to females among nonhuman primates and it is proposed that male colouration might provide a cue to male quality.
The Indonesian primate trade
CLAIRE WEBBER and K.A.I. NEKARIS
Oxford Brookes University, Oxford
An investigation was conducted into the availability of primates at wildlife markets on the Indonesian islands of Sumatra and Java between July and August 2002. Data suggest a continuing increase in the level of primate trade from earlier studies and that the practice of primate trading in Jakarta, Java is more widespread than previously reported. Macaca fascicularis, Macaca nemestrina, Nycticebus coucang and Trachypithecus auratus were the most commonly traded species. When compared with population data, it is anticipated that T. auratus is the species most at risk from the trade. This study also provides the first documentation of the trade in Tarsius spp. Presently, M. fascicularis and M. nemestrina are not legally protected from capture. Whilst the trade in M. fascicularis is deemed sustainable, it is suggested that M. nemestrina will require protective legislation in the near future. A quarter of primates observed at markets were found to be suffering from one or more physical or behavioural conditions. Cage space and hygiene were found to be important predictors of primate welfare and it is recommended that guidelines governing these factors should be introduced. In addition, enforcement actions are required to prevent levels of trade increasing further and to ensure the conservation of Indonesia's primate populations.
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