Social network inheritance and differentiation in wild baboons

Immatures' social development may be fundamental to understand important biological processes, such as social information transmission through groups, that can vary with age and sex. Our aim was to determine how social networks change with age and differ between sexes in wild immature baboons, group-living primates that readily learn socially. Our results show that immature baboons inherited their mothers' networks and differentiated from them as they aged, increasing their association with partners of similar age and the same sex. Males were less bonded to their matriline and became more peripheral with age compared to females. Our results may pave the way to further studies testing a new hypothetical framework: in female-philopatric societies, social information transmission may be constrained at the matrilineal level by age- and sex-driven social clustering

Neuromechanical Mechanisms of Gait Adaptation in C. elegans: Relative Roles of Neural and Mechanical Coupling

Understanding principles of neurolocomotion requires the synthesis of neural activity, sensory feedback, and biomechanics. The nematode \textit{C. elegans} is an ideal model organism for studying locomotion in an integrated neuromechanical setting because its neural circuit has a well-characterized modular structure and its undulatory forward swimming gait adapts to the surrounding fluid with a shorter wavelength in higher viscosity environments. This adaptive behavior emerges from the neural modules interacting through a combination of mechanical forces, neuronal coupling, and sensory feedback mechanisms. However, the relative contributions of these coupling modes to gait adaptation are not understood. The model consists of repeated neuromechanical modules that are coupled through the mechanics of the body, short-range proprioception, and gap-junctions. The model captures the experimentally observed gait adaptation over a wide range of mechanical parameters, provided that the muscle response to input from the nervous system is faster than the body response to changes in internal and external forces. The modularity of the model allows the use of the theory of weakly coupled oscillators to identify the relative roles of body mechanics, gap-junctional coupling, and proprioceptive coupling in coordinating the undulatory gait. The analysis shows that the wavelength of body undulations is set by the relative strengths of these three coupling forms. In a low-viscosity fluid environment, the competition between gap-junctions and proprioception produces a long wavelength undulation, which is only achieved in the model with sufficiently strong gap-junctional coupling.The experimentally observed decrease in wavelength in response to increasing fluid viscosity is the result of an increase in the relative strength of mechanical coupling, which promotes a short wavelength.Comment: Pages 25, Figures 14. Submitted to SIAM Journal on Applied Dynamical System

Phenotypic assortment in wild primate networks: implications for the dissemination of information.

Open Access article published under Creative Commons Attribution Licence.Final published version© The AuthorsElectronic supplementary material is available at http://dx.doi.org/10.1098/rsos.140444 or via http://rsos.royalsocietypublishing.org.This paper is a publication of the ZSL Institute of Zoology’s Tsaobis Baboon Project.Individuals' access to social information can depend on their social network. Homophily-a preference to associate with similar phenotypes-may cause assortment within social networks that could preclude information transfer from individuals who generate information to those who would benefit from acquiring it. Thus, understanding phenotypic assortment may lead to a greater understanding of the factors that could limit the transfer of information between individuals. We tested whether there was assortment in wild baboon (Papio ursinus) networks, using data collected from two troops over 6 years for six phenotypic traits-boldness, age, dominance rank, sex and the propensity to generate/exploit information-using two methods for defining a connection between individuals-time spent in proximity and grooming. Our analysis indicated that assortment was more common in grooming than proximity networks. In general, there was homophily for boldness, age, rank and the propensity to both generate and exploit information, but heterophily for sex. However, there was considerable variability both between troops and years. The patterns of homophily we observed for these phenotypes may impede information transfer between them. However, the inconsistency in the strength of assortment between troops and years suggests that the limitations to information flow may be quite variable.Churchill College, University of CambridgeNatural Environment Research Council (NERC)Leakey FoundationAnimal Behavior Society (USA)International Primatological SocietyExplorers Fun

Animal personality: What are behavioural ecologists measuring?

© 2012 The Authors. Biological Reviews © 2012 Cambridge Philosophical SocietyThis is the peer reviewed version of the article available in final published form via DOI: 10.1111/brv.12007.The discovery that an individual may be constrained, and even behave sub-optimally, because of its personality type has fundamental implications for understanding individual- to group-level processes. Despite recent interest in the study of animal personalities within behavioural ecology, the field is fraught with conceptual and methodological difficulties inherent in any young discipline. We review the current agreement of definitions and methods used in personality studies across taxa and systems, and find that current methods risk misclassifying traits. Fortunately, these problems have been faced before by other similar fields during their infancy, affording important opportunities to learn from past mistakes. We review the tools that were developed to overcome similar methodological problems in psychology. These tools emphasise the importance of attempting to measure animal personality traits using multiple tests and the care that needs to be taken when interpreting correlations between personality traits or their tests. Accordingly, we suggest an integrative theoretical framework that incorporates these tools to facilitate a robust and unified approach in the study of animal personality. © 2012 Cambridge Philosophical Society.FennerSchool of Environment and SocietyResearch School of BiologyZoological Society of LondonNatural Environment Research Council (NERC

Psilocybin links binocular rivalry switch rate to attention and subjective arousal levels in humans

Rationale: Binocular rivalry occurs when different images are simultaneously presented to each eye. During continual viewing of this stimulus, the observer will experience repeated switches between visual awareness of the two images. Previous studies have suggested that a slow rate of perceptual switching may be associated with clinical and drug-induced psychosis. Objectives: The objective of the study was to explore the proposed relationship between binocular rivalry switch rate and subjective changes in psychological state associated with 5-HT2A receptor activation. Materials and methods: This study used psilocybin, the hallucinogen found naturally in Psilocybe mushrooms that had previously been found to induce psychosis-like symptoms via the 5-HT2A receptor. The effects of psilocybin (215μg/kg) were considered alone and after pretreatment with the selective 5-HT2A antagonist ketanserin (50mg) in ten healthy human subjects. Results: Psilocybin significantly reduced the rate of binocular rivalry switching and increased the proportion of transitional/mixed percept experience. Pretreatment with ketanserin blocked the majority of psilocybin's "positive” psychosis-like hallucinogenic symptoms. However, ketanserin had no influence on either the psilocybin-induced slowing of binocular rivalry or the drug's "negative-type symptoms” associated with reduced arousal and vigilance. Conclusions: Together, these findings link changes in binocular rivalry switching rate to subjective levels of arousal and attention. In addition, it suggests that psilocybin's effect on binocular rivalry is unlikely to be mediated by the 5-HT2A recepto

How do foragers decide when to leave a patch? A test of alternative models under natural and experimental conditions.

This is the peer reviewed version of the article which has been published in final form at DOI: http://dx.doi.org/10.1111/1365-2656.12089. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.© 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.A forager's optimal patch-departure time can be predicted by the prescient marginal value theorem (pMVT), which assumes they have perfect knowledge of the environment, or by approaches such as Bayesian updating and learning rules, which avoid this assumption by allowing foragers to use recent experiences to inform their decisions. In understanding and predicting broader scale ecological patterns, individual-level mechanisms, such as patch-departure decisions, need to be fully elucidated. Unfortunately, there are few empirical studies that compare the performance of patch-departure models that assume perfect knowledge with those that do not, resulting in a limited understanding of how foragers decide when to leave a patch. We tested the patch-departure rules predicted by fixed rule, pMVT, Bayesian updating and learning models against one another, using patch residency times (PRTs) recorded from 54 chacma baboons (Papio ursinus) across two groups in natural (n = 6175 patch visits) and field experimental (n = 8569) conditions. We found greater support in the experiment for the model based on Bayesian updating rules, but greater support for the model based on the pMVT in natural foraging conditions. This suggests that foragers may place more importance on recent experiences in predictable environments, like our experiment, where these experiences provide more reliable information about future opportunities. Furthermore, the effect of a single recent foraging experience on PRTs was uniformly weak across both conditions. This suggests that foragers' perception of their environment may incorporate many previous experiences, thus approximating the perfect knowledge assumed by the pMVT. Foragers may, therefore, optimize their patch-departure decisions in line with the pMVT through the adoption of rules similar to those predicted by Bayesian updating.Natural Environment Research Council (NERC)Fenner School of Environment and SocietyLeakey FoundationAnimal Behavior Society (USA)International Primatological SocietyExplorers Club Exploration Fun

Phenotypic assortment in wild primate networks: implications for the dissemination of information.

Individuals' access to social information can depend on their social network. Homophily-a preference to associate with similar phenotypes-may cause assortment within social networks that could preclude information transfer from individuals who generate information to those who would benefit from acquiring it. Thus, understanding phenotypic assortment may lead to a greater understanding of the factors that could limit the transfer of information between individuals. We tested whether there was assortment in wild baboon (Papio ursinus) networks, using data collected from two troops over 6 years for six phenotypic traits-boldness, age, dominance rank, sex and the propensity to generate/exploit information-using two methods for defining a connection between individuals-time spent in proximity and grooming. Our analysis indicated that assortment was more common in grooming than proximity networks. In general, there was homophily for boldness, age, rank and the propensity to both generate and exploit information, but heterophily for sex. However, there was considerable variability both between troops and years. The patterns of homophily we observed for these phenotypes may impede information transfer between them. However, the inconsistency in the strength of assortment between troops and years suggests that the limitations to information flow may be quite variable.A.J.C. is supported by a Junior Research Fellowship from Churchill College, University of Cambridge. H.H.M. was supported by a NERC Open CASE studentship (NE/F013442/1). A.E.G.L. is supported by a NERC Quota studentship (NE/J500409/1). The TBP researchers have received funding from NERC, the Leakey Foundation, the Explorers Fund, the Animal Behavior Society (USA) and the International Primatological Society over the 6 years of the study.This is the final version. It was first published by Royal Society Publishing at http://rsos.royalsocietypublishing.org/content/2/5/140444#ack-1