Culture trumps ethnicity!– Intra-generational cultural evolution and ethnocentrism in an artificial society

Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 1
Culture trumps ethnicity!
– Intra-generational cultural evolution and
ethnocentrism in an artificial society
David Hales and Bruce Edmonds
Centre for Policy Modelling
Manchester Metropolitan University

Acknowledgements
• Work was funded by EPSRC,
as part of the “Social
Complexity of Immigration and
Diversity” project, grant
number EP/H02171X.
• The majority of the work was
done by my friend, David
Hales, who has investigated
many tag models
Hales, D. & Edmonds, B. (2018) Intragenerational Cultural Evolution and
Ethnocentrism, Journal of Conflict Resolution,
http://goo.gl/vS9uqN (Open Access)

Ethnocentrism or In-group Bias
• Ethnocentrism, and more generally in-group bias,
is a widely observed empirical phenomena in
human societies having many different aspects
and occurring in many different ‘flavours’ (LeVine
& Campbell 1972)
• People seem to often divide the population into
those who are considered as part of their group or
their ‘type’ (what we will call the in-group) and the
rest who are seen as outsiders (the out-group).
• When there is social agreement about these
divisions this can polarize differences and
increase tensions between the different kinds.

Tags and Groups
‘Tags’ are any trait of an
individual that are
observable by another.
These can be used as a (fallible)
guide to the characteristics of that
individual (e.g. looking like a mad
professor).
Within a social process tags can
help define a group or even bring it
into being.

Axelrod & Hammond 2003
• There are a number of abstract models (Axelrod
and Hammond 2003 etc.) where:
– agents are located on a spatial grid and evolve
– interaction and reproduction are localised on the grid
– agents can not change their behaviour or location
– the ethnic marker may change over generations
• In these, agents eventually come to favour their
in-group defined by an observable ethnic marker
as a result of a genetic process.
• These models focus on long-range,
inter-generation dynamics where no intra-
generational learning can occur.

Motivation
Although (Axelrod and Hammond 2003) is entirely
non-empirical, it has been very influential on the
way some people think about ethnocentrism, e.g.
that:
• Ethnocentrism is a genetic predisposition
• This is an inevitable result of genetic evolution
We wanted to show an alternative, cultural,
explanation of ethnocentrism, just presuming that
humans have a genetic tendency to distinguish
between in and out groups, and tend behave
differently to each (not even presuming that they
prefer their in-group)

The ethno-cultural tag (ECT) model
• We explore within-generation cultural evolutionary
processes in non-spatial environments (because
space just makes the reported effects stronger)
• Agents do not reproduce or die but rather imitate
other and innovate their beliefs and behaviours based
the results of interactions with other agents
• These other agents can be society wide, but are
(probably) members of what they consider to be their
in-group
• Agents have a (fixed) ethnic tag and a (changeable)
cultural tag, so the emergence of ethnicity-based vs.
culture-based cooperation can be explored

The interaction between agents
• Agents play a ‘donation game’ – that is, each agent
may choose to donate to another or not
Each tick (maybe a number of times): each agent:
1. Picks another agent to interact with (mostly) from
own group – however they define this (unless this is
impossible then another at random)
2. They then donate to this other depending on their
strategies for in- and out-groups
• The other gains the value at a cost to the donor
• Thus there is no direct benefit to donor
• Donor does not know if other would donate to them
(because the only things it knows are the other’s tags)

Agent Traits I (tags)
Here the possible ethnic and cultural tags are simply one of a
finite discrete number of possibilities
If you have the same number (e.g. ethnic marker) you have
the same ethnicity, otherwise different
We have tried lots of different ways of doing this (multi-
dimensional vectors, continuous distances etc.) but since we
get essentially the same results we show you this, the
simplest way of doing this.

Agent Traits II (in-group selector)
The in-group selector determines its in-group, as one of:
– those with the same ethnic marker as itself (ethnic);
– those with the same cultural tag as itself (cultural);
– those with the same ethnic maker and cultural tag
(both);
– any other agent without restriction (none).

Agent Traits III (strategy)
Agents can hold one of four possible strategy
combinations in the donation game that is played:
1) shirk against both the in-group and out-group (ss);
2) donate to both the in-group and out-group (dd);
3) donate to in-group, shirk on out-group (ds);
4) shirk on in-group, donate to out-group (sd).

Model Processes
Each tick all agents do the following as follows:
1. Partner Selection: select another in its in-group as
self (if there is one) otherwise another at random
2. Game Interaction: donate to this other or not
depending on strategies and whether other is in- or
out-group
3. Imitation: select another from anywhere, if other’s
payoff > its own, copy the other’s: selector, cultural
tag and strategies (but not, of course, its ethnic tag)
4. Innovation: with small probabilities change (a)
cultural tag to a random other and (b) change one of
its strategies or selector

Model Parameters
• We have tested MANY other possible parameter
changes and variations in implementation
• But the effect is pretty robust within some known
limitations
• I am not going to go into them here, for some of
the details see the paper, or the discussion paper

Measures on the model
• All measures are a float in [0, 1] and are averages
(over 10 runs) of these calculated over the last
1000 ticks of each 3000 tick run
High
Low
Low
Low
Low
Low
Low

Some Typical Runs
(a) shows domination of the population by the
cultural selector after initial domination by both

Some Typical Runs
(b) shows an oscillation between the two. Notice
that when sb is high ie is low

Some Typical Runs
(c) shows a more typical run in which sc dominates

Some Typical Runs
(d) shows a run where sb comes to dominate

Cultural groups forming and dying

Cross section of culturally defined group

Cross section of culture+ethnic defined
group

Dominating Model Process
On inspection of many runs the following two
processes seem to dominate the dynamics:
• By chance a new “seed group” of two mutual
cooperators appears, these have a high mutual
donation and hence are imitated by others; the
group grows quickly producing a surge of
whatever kind of selector were in the seed
• After a while the group is “infected” by defecting
individuals who receive but do not donate (by
innovation), the payoff of agents in the group
gradually diminishes and eventually individuals
copy a new group

NE=1, 2, 3 cases
With bigger NE, inter-ethnic donation rates increase,
and the cultural selector increasingly dominates the
both selector, but rest is very similar
NE
dr ie sn sc se sb ss ds sd dd
1 0.926 0.000 0.003 0.443 0.002 0.552 0.053 0.875 0.006 0.067
0.003 0.000 0.000 0.264 0.000 0.264 0.003 0.016 0.002 0.015
2
0.917 0.392 0.002 0.778 0.003 0.218 0.061 0.872 0.005 0.063
0.008 0.117 0.000 0.236 0.000 0.236 0.007 0.012 0.001 0.013
4
0.921 0.725 0.002 0.963 0.003 0.033 0.057 0.880 0.005 0.058
0.007 0.014 0.000 0.019 0.000 0.019 0.006 0.013 0.001 0.009

General Observations of the Model
• High donation rates occur when game interaction is
biased towards the in-group and learning is
population wide.
• In general, cultural groups “trump” ethnic groups and
no pure ethnocentrism emerges. Most agents come to
ignore the ethnic marker in defining their in-groups
• In a significant minority of circumstances a form of
ethnocentrism does emerge based on in-groups
defined by both cultural tag and ethnic marker.
• Suggests hypothesis: that group-based
cooperation/discrimination is a result of cultural
adaptation and that ethnic-based cooperation occurs
only as a special kind of culture-based cooperation

Conclusions
• High donation rates occur between agents sharing the
same cultural tag.
• Cultural tag groups trump ethnic groups and no pure
ethnocentrism emerges.
• A form of ethnocentrism does emerge based on in-
groups defined by both the cultural tag and ethnic
marker combined.
• It is the success of the cultural tag processes that
allows for the promotion of discrimination based on
ethnic markers and cultural tags…
• … This occurs when small early-stage tag groups
happen to be ethnically homogeneous through
random variation in their composition.

Interpretation Warning!
Real people in real societies do not change their beliefs and
behaviours based on simple imitation or random changes.
People are attached to particular beliefs and practices for
many reasons other than individual benefit. In fact they may
be the basis of identity itself and may be held even when
they are of no benefit at all. Social behaviours and beliefs
result from a complex interplay of upbringing, personal
experience, social expectations and norms and are not only
the result of adaption of strategy and the basis of judging
who is “in-group”. Cultural groups may fall as well as rise.
Your social capital is at risk if you do not keep up your social
obligations. Membership of any cultural or ethnic group is
subject to terms and conditions. See website for details.
This model merely tests assumptions about the necessity for
a genetically-determined ethnic bias and explores how
cultural mechanisms might be responsible.

The End!
These slides are at: http://slideshare.net/BruceEdmonds
David Hales: http://davidhales.com
Bruce Edmonds: http://bruce.edmonds.name
Centre for Policy Modelling: http://cfpm.org
Discussion paper is at: http://cfpm.org/discussionpapers/152
Published paper is at: http://goo.gl/vS9uqN (Open Access)
Supplementary material: http://goo.gl/eZX2TW
The model code is at: https://comses.net/codebases/4744

Possible game interactions between
agents within early-stage groups
Some possible game interactions between agents within small (early
stage) tag groups. Circles represent agents and indicate payoffs, arrows
donations, shading represents ethnicity. (a–e) Show ethnically
homogenous groups and (f–i) show mixed groups.

Inter-ethnic donation rate and
prevalence of “both” selector (NE=2)
(left) shows inter-ethnic donation rates (ie).
(right) shows both prevalence of “both” selector

Cumulative distribution of tag group sizes and
their total area for a simulation run.

Early-stage ethnic homogeneity
Early-stage ethnic homogeneity for groups reaching size 10
agents, shown for each stage of initial (rising edge) group
size from 2 to 10

Culture trumps ethnicity!– Intra-generational cultural evolution and ethnocentrism in an artificial society

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