Session 10: From Small to Large Groups

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Session 10 From Small to Large Groups
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Questions

• When and why did humans develop the capacity to
  operate in large groups?
• What are the obstacles to achieve large scale
  cooperation?
• What mechanisms, cognitive, emotional, and
  behavioral, enable humans to bond with each other
  in large units?
• How can we foster cooperation in modern society?

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The Problem
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Social brain hypothesis (Dunbar, 2003)

• Humans have a large brain in order to cope with
  the demands of a complex social environment
  rather than the physical environment
• If this is true then as social complexity
  increases between species we should ee an
  increase in brain power
• How to measure social complexity?

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Social brain hypothesis (Dunbar, 2003)

• Brain size is an adaptation for network size
  the need to maintain bonds between ever larger
  and more complex social groups
• Particularly increase in neocortex social
  cognition functions
• Machiavellian intelligence ability to
  manipulate social relationships
• Theory of Mind ability to understand that
  others also have a mind (Baron-Cohen, 1994)
• Between species correlations between neocortex
  ratio and group size (primates, mammals)

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The Social Brain Hypothesis

• Group size is a function of neocortex volume
• Neocortex ratio neocortex vol/rest of brain
• i.e. thinking part of brain

Monkeys
Apes
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Evolutionary analysis Why we moved away from
small kin-based groups?

• Most social animals (including many nonhuman
  primates) live in kin groups only
• Kin cooperation is not really a puzzle (se kin
  selection theory)
• Genus Homo has lived in larger units for some
  time now, according to the brain data (Dunbar,
  1993) around 1.5 MYA.
• What were the pressures to increase group size?
• Ecological pressures dispersed resources
  (sharing waterholes, resource variability)
  fission-fusion societies (Dunbar, 2004)
• Safety pressures (competition between rival
  groups predator avoidance) Alexander, 1979)

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Evolutionary analysis Costs and benefits of
living in large groups

• Benefits
• Resource exploitation
• Group defense
• Costs
• Intragroup competition (over resources)
• Coordination problems
• Freerider problems (avoiding and dealing with
  cheaters)

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Solutions

• New ways of finding partners evolution of
  (social) intelligence and theory of mind (mind
  reading)
• Purpose to use tactical deception to find mates
  and cooperation partners
• New ways of communication evolution of language
• Purpose to communicate to several people at the
  same time and to people not there (symbolic
  language)
• New ways of grooming evolution of laughter,
  music, dance, religion
• Purpose To make larger groupings more cohesive

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The psychological literature Predictions

• 1. Human social network size should be around 150
  people (where everyone knows everyone)
• Religious communities (Hutterites)
• Aborigine groups
• Christmas card lists

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Human Social Network Size

• A study of Xmas card distribution lists in
• 43 long-suffering participants
• Mean cards sent 68.2
• Mean recipients 153.5
• Mode ? 120

Mean
Hill Dunbar (2003)
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The Expanding Circles

• Human groupings are
• limited by
• frequency of
• interaction
• capacity for
• emotional closeness

Intensity
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15
35
80
150
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Predictions

• 2. Cooperation should decrease with group size
• Overwhelming evidence (Marwell Schmitt, 1972)
• Kerr (1989) found that people feel their
  contribution does not matter once groups become
  too large

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Predictions

• 3. Communication enables people to solve social
  dilemmas
• - Dawes, McTavish, Shaklee (1977)

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Communication and cooperation
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Predictions

• 4. People should be able to identify with and
  sacrifice for large groups
• Literature on organizational (Ellemers et al.,
  1998) and national loyalty (Stern, 1995)
• Social movement participation (Simon et al.,
  1998)
• Community identification and water conservation
  (Van Vugt, 2001)

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Community identification predicts water
conservation during a drought (Van Vugt, 2001)
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Prediction Laughter increases bonding in groups

• 5. Our recent study

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Cooperation in modern society

• Use the social brain and work-around the
  limitations of it
• Turn large units into smaller groupings that
  people can more easily identify with
• Have charismatic leaders that can mobilize the
  masses (leaders with personal qualities)
• Promote gossip and information exchange so that
  people are concerned about their reputations
  (media)
• Have systems in place to punish and ostracize
  cheaters

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Take-home message

• Humans have the capacity to function in large
  groups
• This is made possible by a number of cognitive
  and affective evolved mechanisms unique to
  humans
• Theory of mind
• Language
• Laughter, identification
• Culture (?)
• To sustain cooperation in our large, complex
  society requires us to use the social brain
  optimally and work around its limitations

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Summary of module

• Take a particular group-related behaviour
• Ask yourself what the proximate functions of this
  behaviour are when do people show it, how and
  why do they show it?
• Ask yourself what the ultimate function of this
  behaviour is did it yield selective advantages
  in our evolutionary past or is it a recent
  cultural phenomenon?
• Use information from both the evolutionary and
  social psychology perspectives to getter a better
  picture
• If the group behaviour is a problem suggest
  realistic solutions that take into account the
  evolutionary basis of the behaviour

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Evaluation of module

• What did you learn from this course?
• What did you think of Ridleys book?
• Which session did you enjoy most?
• Which session did you enjoy least?
• How can this course be improved?

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Sessions

• 1 Why humans live in groups
• 2 The puzzle of human altruism
• 3 Reputations matter
• 4 Status, conformity and obedience
• 5 Dominance or leadership?
• 6 The nature of group cohesion
• 7 Aggression within groups
• 8 Aggression between groups
• 9 Group performance and decision-making
• 10 Group size

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Evolution of religion (Discussion)

• What is religion?
• What are the main aspects of religion?
• Are there any adaptive benefits to religious
  beliefs?
• If so, which are they? Individual-level or
  group-level benefits
• If not how did religion emerge? (byproduct
  hypothesis)
• What are the ultimate and proximate functions of
  religion?
• What are the cognitive capacities needed to get
  religious beliefs? (evolutionary history)
• Can modern humans do without religion?

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Functions of religion

• Coping with uncertainty (naive scientific
  beliefs)
• Group cohesion and solidarity (supernatural
  punishment Johnson, 2005)
• Self-control