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Real-World Social Networks: Structure and Dynamics Bottom Up

Real-World Social Networks: Structure and Dynamics Bottom Up. Robin Dunbar Institute of Cognitive & Evolutionary Anthropology University of Oxford. The Global Village?. The Internet was based on the promise of enlarging your social world beyond the limits of the local village.

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Real-World Social Networks: Structure and Dynamics Bottom Up

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  1. Real-World Social Networks:Structure and Dynamics Bottom Up Robin Dunbar Institute of Cognitive & Evolutionary Anthropology University of Oxford

  2. The Global Village? • The Internet was based on the promise of enlarging your social world beyond the limits of the local village But does it actually work?

  3. Does Technology Really Widen Your Horizons? The answer from Facebook’s own data seems to be: No Modal number of friends is 120-130 You may list 100s of friends, but you only talk to a few   WHY? Cameron Marlow web-blog

  4. To Begin at the Beginning…. Social Brain Hypothesis • Among primates, social group size is determined by neocortex volume • Predicted group size for humans is ~150 [Dunbar’s Number] Monkeys Apes Dunbar (1992, 1993)

  5. HumanSocial Networks These all have mean sizes of 100-200 Neolithic villages 6500 BC 150-200 military units (company) (N=10) 180 * Hutterite communities (N=51) 107 Nebraska Amish parishes (N=8) 113 business organisation <200 ideal church congregations <200 Doomsday Book villages 150 C18th English villages 160 * GoreTex Inc’s structure 150 Research sub-disciplines (N=13) 100-200 Twitter personalised contacts 100-200 Small world experiments (N=2) 134 Hunter-Gatherer communities 148 Xmas card networks 154 Twitter exchange contacts Gonçalves et al. (2011) Killworth et al (1984)) Her 152 facebook friends ….remembered forever “Reverse” Small World Experiments 100 10 Hunter-Gatherer Societies Dunbar (1993) Individual Tribes SusyJ87 http://www.youtube.com/watch?v=ApOWWb7Mqdo Hill & Dunbar (2003) Xmas Card Networks Dunbar (1993, 2008)

  6. BUT….Human Networks are NOT Homogenous Less like this …..and more like this

  7. Intimacy, Frequency and Trust Contact frequency differs across layers There is a relationship between frequency of contact and intimacy Hill & Dunbar (2003)

  8. The Fractal Periodicity of Human Group Sizes Sizes of Hunter-Gatherer Groupings Peak at=5.4 Slope  3 Social Groupings Database [N=60] Hamilton et al (2007) Peak at=5.2 Xmas Card Database Scaling ratio = exp(2π/) = 3.2 and 3.3 Zhou, Sornette, Hill & Dunbar (2005)

  9. The Friendship Shells • Our social worlds consist of layers of relationships • …with 150 as the core • number • ….and a scaling ratio • of ~3 • …but extending beyond • to 500, 1500 Intensity EGO 5 15 50 150 1500 500

  10. Intimacy, Frequency and Trust Contact frequency and emotional closeness differs across layers The layers appear to be quite discrete Mean contact frequency/day Mean Emotional Closeness Network Layer Sutcliffe et al (in press)

  11. Network Structure Has Consequences Happy Intermediate Unhappy Fowler et al (2008) Christakis (2007) Happiness and obesity are contagious …with effects up to three degrees away

  12. Network Density is Important • How well integrated your close network is influences your willingness to act altruistically Would you lend £5000? Curry & Dunbar (in press)

  13. The Circles of Acquaintanceship • Our networks are structured by more than just social closeness Intensity EGO FRIENDS Our networks are also split roughly equally between Family (kin) and Friends – two separate sub-networks that intersect 5 FAMILY 15 50 150 500

  14. The Kinship Factor 80 close networks Inner layers Outer layers • Our networks consist of about 50% kin [family] • Kin are given priority over Friends • If you come from a large extended family, you have fewer friends! Slope  -1 250 complete networks -0.3 < slope< -0.9 Total Kin

  15. Blood is Thicker Than Water • We value kin more than we value friends ….. in any given layer of the network How much I value you relative to myself Welfare Trade-off Ratio Family Friends 5 15 150 Network Layer Curry & Dunbar (in press)

  16. Stable Family, Fragile Friends Stay KIN Move Friends Change in Network Layer Change over Time 0 9 18 months Kin Friends Roberts & Dunbar (2011)

  17. by change in activity score by change in contact frequency How to Prevent Relationships Decaying Change in Emotional Closeness months 0-9 Roberts & Dunbar (2010)

  18. What Makes Relationships Work? Primate social bonds seem to involve two distinct components: • An emotionally intense component [=grooming] • A cognitive component [=brain size + cognition]

  19. The Limits to Intentionality... A natural limit at 5th order intentionality: “I intend that you believe that Fred understands that we want him to be willing to [do something]…” [level 5] % Correct Intentionality Level

  20. The Cognitive Limits to Sociality 5th order seems to be the limit “I intend that you believe that Fred understands that we want him to be willing to [do something]…” Intentionality correlates with size of support clique The Orders [or Levels] of Intentionality Stiller & Dunbar (2007) Powell et al (2010)

  21. In a stereological analysis of gross volume: best predictor of network size and intentional competence is orbitofrontal PFC volume In a fine-grained VBM (voxel) analysis: overlap of network size and intentional competence in the orbitovental PFC Insights from Neuroimaging Powell et al (2010 & in press) Lewis et al (in press)

  22. How Grooming Works An experimental study with monkeys Opiates block social drive; Opiate-blockers enhance social drive • endorphins are relaxing • They create a psycho-pharmacological environment for building trust? Sal

  23. Grooming Time in Humans? • If we bonded our groups using the standard primate mechanism ….we would have to spend 43% of the day grooming

  24. Grooming Time in Humnas? • In fact, we spend only 20% of our time in social interaction …..from a sample of 7 societies from Dundee to New Guinea • How do we bond our super-large communities?

  25. Laughter as Virtual Touch? Change in Pain Threshold in Response to Laughter Factual vs Comedy Videos • Pain threshold as an assay for endorphin activation • Laughter as a form of virtual grooming to bond more individuals? Comedy EdinburghFringe Edinburgh Fringe Neutral • Procedure: • pain test • video/activity • pain re-test Dunbar et al (submitted)

  26. Nothing Beats Reality….? • Both perceived happiness AND laughter rates, F2F and Skype are better than all other media • Laughter influences happiness [except in Skype] • And may be more important than duration of interaction in promoting satisfaction Satisfaction Rating Frequency of Laughter Satisfaction Rating Vladovik et al (submitted) NOYES Laughter

  27. Synchony Ramps up the Endorphins Change in pain threshold before and after 45 mins rowing work-out on ergometers in the gym: Alone vs in a virtual boat Alone Group Alone Group

  28. With Thanks to…. Comparative brains: Dr Susanne Shultz Social Networks and behaviour: Dr Sam Roberts Dr Tom Pollet Dr Oliver Curry Dr Holly Arrow Dr Jens Binder Prof Alistair Sutcliffe Tatiana Vlahovic Dr Wei Zhou Dr Russell Hill Prof Didier Sornette Prof Mark van Vugt Rebecca Baron, Ellie Pearce and Anna Frangou Neuroimaging: Amy Birch Joanne Powell Rachel Browne Dr Penny Lewis Prof Neil Roberts Dr Marta García-Fiñana Funding: British Academy EPSRC ESRC Leverhulme Trust EU-FP7

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