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Guest Lecture UvA / UAntwerpen / Leiden

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Thomas Pollet

on 5 January 2016

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Transcript of Guest Lecture UvA / UAntwerpen / Leiden

Guest Lecture: The social brain hypothesis
Theory of mind
Communication science /computing
Dunbar, 1998
Business / organization
Humans are primates
Primates have (on average)
larger brains than 'typical' mammals, controlling for body weight
20 to 50x >
What distinguishes
humans from other primates (\animals)?
Pure evil @ art happy
Humans are atypical primates
Neocortex "seat of cognition"
Brain roughly 3x larger than
"average primate" (controlling for body
Falk, 1980
More neocortex
What explains large primate
brain (and more neocortex)?
* Development (/allometry)
Big brains are not simply scaled-up
versions of small brains
* Nutrition
Brain consists of costly tissue.
Long development span.
Bipedal locomotion
Capacity for cumulative culture
("Full Blown") language
"Large brain for body weight"
Sangild, 2006, Exp. Biol. Med.
cary wolinski
Dr. Thomas Pollet
Dept. of Experimental and Applied psychology
Developmental psychology
Schoenemann, 2006
Snodgrass et al., (2009) in J.-J. Hublin and M.P. Richards (eds.), The Evolution of Hominin Diets: Integrating Approaches to the Study of Palaeolithic Subsistence, pp. 15–29. Springer NY.
Frugivory vs. folivory
Mental map
Better extraction of
* Sociality
Upper (successful) limit: 35
Take home message managing a social network online
might be even harder (especially when you have to do stuff together)... .
Allen, 2005
Upper (successful) limit: 40-45.
(Guilds seldom exceed
Tax office
Gladwell, 2000; Dunbar, 2011
Optimal school size?
NFER report
Several other factors
moderate. (e.g. single
sex vs mixed).
>360,000 16-17 year olds
from 2,953 schools
Optimum: 175-200
Then why do primates live in groups?
Ultimate pressure is likely predation

Dunbar, 1998
(Hill & Dunbar, 1998, Dunbar, 2010)
Group size increases pressures on social cognition
Larger groups --> stress
Grooming: maintaining key relationships
+ 'endorphin kick'
So what?

We can then use equations
to predict likely ancestral upper group size
in humans

Dunbar's number: group size of 150. (147.8)
What is the evidence for Dunbar's number
(number of meaningful
social relationships)
Upper limit to facebook?
Upper limit to twitter.
Optimal functional
army unit?
(Dunbar, 1993, 2008)
Company size: 130-223
Social network studies
Hill & Dunbar 2003, Hum. Nat.
Networks are not undifferentiated
Literature, arts
linguistics/ cogn. psychology
Machiavellian intelligence
Yanomamö village size
Archeology: Anglo-Saxony, Mesopotamia, New Guinea
Aboriginal clans
Optimal 'sect' size
Hutterites: "150 rule"
Iannacone, 1992, J. Pol. Econ.
Sect: M= 173 (121)
Dunbar, 1993, J. Hum. Evol.
Sectlike: M= 335 (186)
Chagnon, 1992; Dunbar, 2003
Dunbar, 2003
Dunbar, 1998
1. 'natural' groupings
11. Social network studies
around 148
Natural groupings
Social Brain hypothesis:
One potential explanation for language
Among primates: largest time budget
spent on grooming 20%
Vast majority of ' every day' language is social.
(~ 60%)
Humans would have to spend double time
Endorphin kick: laughter
e.g. Mehu & Dunbar, 2008
Dunbar, 1992, 1993, 1998, 2008
I know that Mark knows
that Ronald knows that Bram knows...
Level 0: preferences/desires
Level 1: beliefs
Level 2: beliefs about
someone else's beliefs
Level 3: beliefs about
someone else's beliefs
about someone else's
Liddle & Nettle, (2006). JCEP
--> related to autism
--> development
Baron Cohen, 1995
Shakespeare: 5+
Woolf: 6
Dunbar et al., 1994; Zunshine, 2004
Moretti, 2011
All of these
Dunbar, 1998
The End
Roberts et al., 2009
Social networks
Do humans also
have the largest brain
in absolute terms?

* Slides
* Article by Dunbar.
* Some knowledge / critical thinking
on social brain hypothesis

* an example of hypothesis development (and
testing) and how evolutionary theory can lead to novel hypotheses.

* Social Brain hypothesis

* Implications + 'new research'
How much does a brain weigh?
5,620 g
1300-1400 g.
Hedgehog Dilemma /
Porcupine problem
What is an endorphin?

Where is it produced?

What activities release it?
End of part 1
What makes human language unique?

Theories of language evolution

Potential pre-adaptations

Consensus and controversy.

What is a 'language'?
No agreed upon definition.

Working definition: ‘language consists of a string of words ordered by the rules of grammar to convey meaning’. (Doupe and Kuhl, 1999)

Perhaps best to compare it to other forms of animal communication.
Specific calls for:
Part II: further suggested
A key review article

Christiansen & Kirby, 2003
What criticisms
can you come up

What pre-adaptations to language
can you name (think back to Annemie's class)?
Question then becomes:
What selected for culture?

--> Fleur.
Part of this is covered in the book
but pay attention to slides.

An example question
could be:

Discuss the social brain hypotheses
versus competing hypotheses for primate
brain evolution.

Critically discuss what makes human language
unique compared to other forms of animal

What are 'mirror neurons'?. Why is the debate
about them important.
* an example of successful hypothesis
("better" than other explanations of primate
brain evolution).
In a distilled form: predation --> group living --> selection on social cognition -->
increase in Neocortex.

* novel way of thinking about brain evolution.

* Framework for certain human behaviors (broader picture).

One potential limitation:
line of sight (Dunbar, 1999)
In both cases (biological/cultural)
an evolutionary perspective is useful.
What limitation does
gesturing have (vs. speech?)

Now discussion of what you
have read... .

Dunbar (1992)
* Chomsky: 'Universal grammar'

* Bickerton: 'Language bioprogram' (many theories)

* Pinker: 'language instinct

* Dunbar: 'Grooming to language'

* Deacon: 'Symbolic species'

* Miller: 'Mating mind': sexual selection.
Theories we covered
(in monkeys and apes)
Multidisciplinary approach. (which disciplines?)
Seyfarth calls these like 'words'
(and in earlier work
tentatively called it language)
C. Slobodchidkoff
Monkeys don't imitate
complex actions.
Mirror neurons fire when
animal performs an action
or sees another (conspecific)
performing the action.
Christiansen & Kirby (2003).
structure 1
to structure 5
Some proposed traits
Full transcript