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

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Presentation on theme: "Real-World Social Networks: Structure and Dynamics Bottom Up Robin Dunbar Institute of Cognitive & Evolutionary Anthropology University of Oxford."— Presentation transcript:

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 Facebooks 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 Cameron Marlow web-blog WHY?

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 [Dunbars Number] Apes Monkeys Dunbar (1992, 1993)

5 Human Social 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 Incs 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 Reverse Small World Experiments Hunter-Gatherer Societies Xmas Card Networks Individual Tribes Dunbar (1993) Hill & Dunbar (2003) Killworth et al (1984) ) Twitter exchange contacts 100 10 Gonçalves et al. (2011) Dunbar (1993, 2008) Her 152 facebook friends ….remembered forever SusyJ87

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

9 The Friendship Shells 5 15 50 150 Intensity EGO 5001500 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

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

11 Network Structure Has Consequences Fowler et al (2008) Christakis (2007) Happy Intermediate Unhappy 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 Estimates of Fixed Effects a ParameterEstimateStd. Error dftSig. Intercept2.350.60321.593.920.00 AGREEABLENESS0.070.05283.661.470.14 CONSCIENTIOUSNESS-0.090.06281.99-1.540.12 YEARS_KNOWN0.030.002139.469.810.00 CONTACT_FREQUENCY0.340.022127.6313.880.00 AGREEABLENESS of TARGET0.090.012065.937.340.00 CONSCIENTIOUSNESS of TARGET0.120.022079.317.760.00 NETWORK DENSITY0.050.022170.822.790.01 Would you lend £5000? Curry & Dunbar (in press)

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

14 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! 250 complete networks -0.3 < slope< -0.9 80 close networks Total Kin Slope -1 Inner layers Outer layers The Kinship Factor

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

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

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

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 5 th 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 5 th 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 Stiller & Dunbar (2007) Powell et al (2010) The Orders [or Levels] of Intentionality

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 Powell et al (2010 & in press) Insights from Neuroimaging Lewis et al (in press)

22 How Grooming Works endorphins are relaxing They create a psycho- pharmacological environment for building trust? An experimental study with monkeys Opiates block social drive; Opiate-blockers enhance social drive 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 Procedure: pain test video/activity pain re-test Edinburgh Fringe Neutral Comedy Laughter as Virtual Touch? Edinburgh Fringe Pain threshold as an assay for endorphin activation Laughter as a form of virtual grooming to bond more individuals? Change in Pain Threshold in Response to Laughter Factual vs Comedy Videos Dunbar et al (submitted)

26 Nothing Beats Reality….? Both perceived happiness AND laughter rates, F2F and Skype are better than all other media o Laughter influences happiness [except in Skype] o And may be more important than duration of interaction in promoting satisfaction Vladovik et al (submitted) Satisfaction Rating Frequency of Laughter NO YES Laughter

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

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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