RealWorld 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? l The Internet was based on the promise of enlarging your social world beyond the limits of the local village But does it actually work?

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

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

Twitter exchange contacts Human Social Networks These Gonçalves et al. (2011) Her 152 facebook friends all have mean sizesforever of …. remembered “Reverse” Small World Experiments 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 C 18 th English villages 160 * Gore. Tex Inc’s structure 150 Research sub-disciplines (N=13) 100 -200 Twitter personalised contacts 100 -200 Killworth et al (1984)) 100 10 Dunbar (1993) Individual Tribes Hunter-Gatherer Societies Susy. J 87 http: //www. youtube. com/watch? v=Ap. OWWb 7 Mqdo Small world experiments (N=2) 134 Hunter-Gatherer communities Xmas card networks Dunbar (1993, 2008) 148 154 Xmas Card Networks Hill & Dunbar (2003)

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

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

Sizes of Hunter-Gatherer Groupings The Fractal Periodicity of Human Group Sizes 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)

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

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

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

Network Density is Important l How well integrated your close network is influences your willingness to act altruistically Estimates of Fixed Effectsa Would you lend £ 5000? Parameter Estimate Std. Error df t Sig. Intercept 2. 35 0. 60 321. 59 3. 92 0. 00 AGREEABLENESS 0. 07 0. 05 283. 66 1. 47 0. 14 CONSCIENTIOUSNESS -0. 09 0. 06 281. 99 -1. 54 0. 12 YEARS_KNOWN 0. 03 0. 00 2139. 46 9. 81 0. 00 CONTACT_FREQUENCY 0. 34 0. 02 2127. 63 13. 88 0. 00 AGREEABLENESS of TARGET 0. 09 0. 01 2065. 93 7. 34 0. 00 CONSCIENTIOUSNESS of TARGET 0. 12 0. 02 2079. 31 7. 76 0. 00 NETWORK DENSITY 0. 05 0. 02 2170. 82 2. 79 0. 01 Curry & Dunbar (in press)

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

The Kinship Factor 80 close networks Inner layers l Slope -1 Our networks consist of about 50% kin [family] Outer layers l l 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 Total Kin

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

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

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

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

The Limits to Intentionality. . . % Correct 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] Intentionality Level

The Cognitive Limits to Sociality The Orders [or Levels] of Intentionality l 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]…” l Intentionality correlates with size of support clique Stiller & Dunbar (2007) Powell et al (2010)

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

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

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

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

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

Nothing Beats Reality…. ? l Both perceived happiness AND laughter rates, F 2 F and Skype are better than all other media Satisfaction Rating o Laughter influences happiness [except in Skype] o And may be more important than duration of interaction in promoting satisfaction Frequency of Laughter Satisfaction Rating Vladovik et al (submitted) NO YES Laughter

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

Comparative brains: l Dr Susanne Shultz Social Networks and behaviour: l Dr Sam Roberts l Dr Tom Pollet l Dr Oliver Curry l Dr Holly Arrow l Dr Jens Binder l Prof Alistair Sutcliffe l Tatiana Vlahovic l Dr Wei Zhou l Dr Russell Hill l Prof Didier Sornette l Prof Mark van Vugt l Rebecca Baron, Ellie Pearce and Anna Frangou Neuroimaging: l Amy Birch l Joanne Powell l Rachel Browne l Dr Penny Lewis l Prof Neil Roberts l Dr Marta García-Fiñana With Thanks to…. Funding: British Academy EPSRC ESRC Leverhulme Trust EU-FP 7