Ethnocentrism denotes behaviour and beliefs that are positive towards those who share the same ethnicity and negative towards others. Recent artificial society models have been interpreted as demonstrating how ethnocentrism can evolve under minimal assumptions. In these, evolution is modelled over generations of agents where new agents are born inheriting the ethnicity, behaviours and location of their parents. Behaviour does not change within generations but over many generations and agents only interact with their neighbours. We present a model that considers short-term cultural adaption, where agents may interact with any in a population and do not die or give birth but imitate and innovate their behaviours. While agents retain a fixed ethnicity they have the ability to form and join cultural groups and to change how they define their in-group based on both ethnic and cultural markers (or tags). We find that over a range of parameters cultural identity rather than ethnocentrism becomes the dominant way that agents identify their in-group producing high levels of positive interaction both within and between ethnicities. However, in some circumstances, cultural markers of group preference are supplemented by ethnic markers. In other words, whilst pure ethnocentrism (based only on ethnic identity only) is not sustained, groups that discriminate in terms of a combination of cultural and ethnic identities do occur. In these less common cases, high levels of ethnocentric behaviours evolve and persist – even though the ethnic markers are arbitrary and fixed – but they only emerge when combined with culture centric behaviour. Furthermore, cooperative ethnocentric groups do not emerge in the absence of cultural processes. The latter suggests the hypothesis that observed ethnocentrism in observed societies need not be the result of long-term historical processes based upon ethnic markers but could be more dependent upon short run cultural ones. We discuss these results as well as the danger of over interpretation of artificial society models.

1. 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

2. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 2
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).
• Where such distinctions are made there is often a
propensity for more positive behaviour towards
the in-group than towards the out-group.

3. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 3
Previous Models
• There are a number of abstract models (Axelrod
and Hammond 2003; Hammond & Axelrod 2006;
Jansson 2013; Roitto 2015) 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.
• These models focus on long-range, inter-
generation dynamics where no intra-generational
learning can occur.

4. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 4
The ethno-cultural tag (ECT) model
• We explore within-generation cultural evolutionary
processes in non-spatial environments
• Agents do not reproduce or die but rather imitate
and innovate their beliefs and behaviours based
the results of interactions with other agents
• These other agents can be society wide rather
than localised, but are (probably) members of
what they consider to be their in-group
• Agents have a (fixed) ethnic marker and a
(changeable) cultural marker, so ethnicity-based
vs. culture-based cooperation can be explored

5. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 5
Agent Traits (in-group selector)
Agents can only distinguish between other agents by
observing their ethnic marker and cultural tag
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).
trait type range
ethnic marker +ve integer [1..NE]
cultural tag +ve integer [1..NC]
in-group selector member of {none, cultural, ethnic, both}
in-group strategy member of {donate, shirk}
out-group strategy member of {donate, shirk}

6. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 6
Agent Traits II (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).
trait type range
ethnic marker +ve integer [1..NE]
cultural tag +ve integer [1..NC]
in-group selector member of {none, cultural, ethnic, both}
in-group strategy member of {donate, shirk}
out-group strategy member of {donate, shirk}

7. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 7
Model Processes
Each tick all agents do the following as follows:
1. Partner Selection: with probability GB select another
in its in-group as self (if there is one) otherwise
another agent at random
2. Game Interaction: donate or not depending on
strategies and whether other is in- or out-group
3. Imitation: with probability LB select another in its in-
group as self (if exists) otherwise another at random,
if other’s payoff > its own, copy other’s selector,
cultural tag and strategies
4. Innovation: with small probabilities change (a)
cultural tag to a random other and (b) change one of
its strategies or selector

8. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 8
Model Parameters
Parameter description range
N number of agents in population 1000
NE number of different unique ethnic markers {1, 2, 4}
NC number of different unique cultural tags 1000
GB game in-group bias {0, 0.5, 1}
LB learning in-group bias {0, 0.5, 1}
CM cultural tag mutation rate 0.01
SM strategy and in-group selector mutation rate 0.001
C cost of making a donation 0.1
B benefit obtained from receiving a donation 0.2

9. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 9
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
Measure description
dr overall donation rate as proportion of all games played
ie inter-ethnic donation rate as proportion of donations made
ss proportion of agents with in-group and out-group shirk
sd proportion of agents with in-group shirk and out-group donate
ds proportion of agents with in-group donate and out-group shirk
dd proportion of agents with in-group donate and out-group donate
sn proportion of agents with the in-group selector type “none”
sc proportion of agents with the in-group selector type “cultural”
se proportion of agents with the in-group selector type “ethnic”
sb proportion of agents with the in-group selector type “both”

10. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 10
Some Typical Runs
(a) shows domination of the population by the cultural selector after initial
domination by both. (b) shows an oscillation between the two. Notice that when
sb is high ie is low. (c) shows a more typical run in which sc dominates. (d)
shows a run where sb comes to dominate. (all NE =2, GB=1, LB=0).
(a) (b)
(c) (d)

11. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 11
Cultural Tag Groups
Simulation Time 
DifferentCulturalMarkers

12. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 12
Donation Rate (dr) for NE=1
Surface plot over parameter space of GB and LB. High
cooperation occurs for low LB and high GB (learn from
anybody, interact only within group). Cases NE=2 and
NE=4 were almost identical.

13. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 13
NE=1, selectors and strategies
in-group selector
none cultural ethnic both
av 0.003 0.443 0.002 0.552
sd (0.000) (0.264) (0.000) (0.264)
In-group / out-group strategies
ss ds sd dd
av 0.053 0.875 0.006 0.067
sd (0.003) (0.016) (0.002) (0.015)

14. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 14
NE=1, 2, 3 cases (GB=1, LB=0)
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

15. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 15
NE=1, 2, 3 cases (GB=0.5, LB=0.5)
Similar picture with lower over-all donation and
more SS strategies. With bigger NE, inter-ethnic
donation rates increase, and the cultural selector
increasingly dominates the both selector.
NE
dr ie sn sc se sb ss ds sd dd
1 0.324 0.000 0.002 0.619 0.002 0.379 0.366 0.630 0.001 0.003
0.018 0.000 0.001 0.290 0.000 0.290 0.037 0.037 0.000 0.000
2
0.312 0.426 0.002 0.840 0.002 0.157 0.387 0.610 0.001 0.003
0.021 0.101 0.001 0.210 0.001 0.210 0.042 0.042 0.000 0.000
4
0.316 0.725 0.002 0.960 0.003 0.037 0.381 0.616 0.001 0.003
0.013 0.009 0.001 0.014 0.000 0.014 0.027 0.027 0.000 0.000

16. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 16
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

17. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 17
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 fast producing a surge of whatever
kind of selector were in the seed individuals
• After a while the group is “infected” by defecting
individuals who receive but do not donate, the
payoff of agents in the group gradually diminishes
and eventually individuals copy a new group

18. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 18
General Observations of the Model
• High donation rates occur when game interaction is
biased towards the in-group (GB ≈ 1) and learning is
population wide (LB ≈ 0).
• In general, cultural groups “trump” ethnic groups and
no 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

19. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 19
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.

20. Culture trumps ethnicity! – Intra-generational cultural evolution and ethnocentrism in an artificial society, David Hales and Bruce Edmonds, Dec 2015, 20
The End!
David Hales: http://davidhales.com
Bruce Edmonds: http://bruce.edmonds.name
Centre for Policy Modelling: http://cfpm.org
The paper is at: http://cfpm.org/discussionpapers/152
The model is available at: http://openabm.org/model/4744
These slides are at: http://slideshare.net/BruceEdmonds