Conferencia Posgrado del Prof. José Manuel Galán Ordax, Universidad de Burgos: "Modelado basado en agentes para simular el pasado. Cooperación social en Tierra del Fuego" impartida el día 22 de Abril de 2015 en la Facultad de Informática

1. MODELADO BASADO EN AGENTES
PARA SIMULAR EL PASADO.
COOPERACIÓN SOCIAL EN TIERRA
DEL FUEGO
#simulpast
Facultad de Informática
Universidad Complutense de Madrid
22 de abril de 2015

2. Aplicaciones de los agentes
Aplicacionesdelosagentes
Integración de empresas
de fabricación
Gestión de la cadena de
suministros
Scheduling
Gestión de materiales
Control aéreo
Medicina
Recuperación de
información
….
Modelado y simulación
de sistemas

3. Modelado basado en agentes
Fuente: Galán, J.M., Izquierdo, L.R., Izquierdo, S.S., Santos, J.I., del Olmo, R., López-Paredes, A. & Edmonds, B. (2009). Errors and Artefacts in
Agent-Based Modelling. Journal of Artificial Societies and Social Simulation 12(1)1 http://jasss.soc.surrey.ac.uk/12/1/1.html

4. “Nuestro laboratorio social”

5. Tendencias

6. Estructura de la presentación
1. Contexto del proyecto
2. El caso de estudio
3. El modelo I
4. Resultados
5. El modelo II
6. Resultados
7. Conclusiones

7. Contexto del proyecto
Fuente: www.Simulpast.net

8. Simulpast

9. • Briz i Godino, I., Izquierdo, L.R., Álvarez, M., Caro, J., Galán, J.M.,
Santos, J.I., Zurro, D. (In Press) Ethnoarchaeology of hunter-fisher-
gatherers societies in the Beagle channel (Tierra del Fuego):
ethnographical sources and social simulation. Revista de
Arqueología Americana
• Santos, J.I., Pereda, M., Zurro, D., Alvarez, M., Caro, J., Galán, J.M.,
Briz I Godino, I. (2015) Effect of Resource Spatial Correlation and
Hunter-Fisher-Gatherer Mobility on Social Cooperation in Tierra
del Fuego. PLoS ONE 10(4): e0121888.
doi:10.1371/journal.pone.0121888
• Briz i Godino, I., Santos, J.I., Galán, J.M., Caro, J., Álvarez, M., Zurro,
D. (2014) Social Cooperation and Resource Management
Dynamics among Late Hunter-Fisher-Gatherer Societies in Tierra
del Fuego (South America). Journal of Archaeological Method
and Theory, 21(2), pp. 343-363, doi: 10.1007/s10816-013-9194-3

10. Los Yámana
Fuente«Pueblos indigenas de Chile-ver» de Createaccount - https://commons.wikimedia.org/wiki/File:Chile_location_map.svg. Disponible bajo la licencia CC BY-
SA 3.0 vía Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Pueblos_indigenas_de_Chile-ver.svg#/media/File:Pueblos_indigenas_de_Chile-ver.svg
• Thomas Bridges
• Martin Gusinde

11. Varamientos de cetáceos o sardinas
(iacasi)

12. • “Ethnographical and archaeological
evidence suggests the existence of
sporadic aggregation events, triggered
by a public call through smoke signals of
an extraordinary confluence of resources
under unforeseeable circumstances in
time and space (a beached whale or an
exceptional accumulation of fish after a
low tide, for example). During these
aggregation events, the different social
units involved used to develop and
improve production, distribution and
consumption processes in a collective
way”.

13. Cooperación
• “We define cooperation as a social relationship that allows certain
social and economic practises to take place in a particular way in
which different social agents are involved; these agents develop
production, distribution and consumption processes collectively so
that the profits/returns/payoff for all participating individuals
increase.These profits/returns/payoffs, which are not necessarily
strictly material in nature, are neither immediate nor uniform (there is
not necessarily a proportional relation between the investment made
and the benefits received). Social benefits such as reputation, which
may lead to future material benefits, may play an outstanding role
here and may even be more important than immediate material
benefits.”
• Alguien que paga un coste para que otro individuo reciba un beneficio
• Dilema social

14. Etnoarchaeological record
1. References about beached whales are frequent and
detailed
2. Songs to bring them to coast
3. Festive social occasion
4. Blubber and mushrooms were the only edible resources
that people stored
5. Social norms punished people that did not notify the
community of the presence of a beached whale

15. Cooperation Mechanisms
Fuente: Nowak, M.A. (2006) Five rules for the evolution of cooperation. Science 314(5805): 1560–1563.

16. Cooperation Mechanisms
Fuente: Nowak, M.A. (2006) Five rules for the evolution of cooperation. Science 314(5805): 1560–1563.

17. Wave when hale whale WWHW
• A social mechanism of indirect reciprocity that promotes
cooperation
• The stochasticity of the natural events that generate
cooperation opportunities
• The characteristics of these events that determine their
visibility (i.e. people’ ease in finding them) and the
chances of someone being caught if they do not
cooperate (defect)
• The relative benefit of the social activities that people
develop when they gather together in aggregations

18. WWHW
• People
• Move
• Call?
• Whales

22. Reputation

25. Results

26. Model II
• Mobility pattern
• Resource Spatial Correlation
• Parameter space exploration

27. Mobility pattern. Brownian motion
• Random walk
• It serves as the null
hypothesis in many theories
• No preferential directions
nor particles (individuals)
with more momentum than
others
• The mean square
displacement (the distance
we can expect a random
walk to progress from its
starting point) scales with
the duration of the walk
Source: http://offsideswithfletcher.files.wordpress.com/2008/07/stagedive.jpg
Source:
http://www.astrosafor.net/Huygens/2002/3
7/fractal/foto11_Brown.GIF
Fuente: Pereda, M. (2014) Random Walks and Lévy Flights. A social-science approach

28. Mobility pattern. Lévy flight motion
• A Lévy flight is a random
walk in which the step-
lengths have a probability
distribution that is heavy-
tailed.
Source:
http://tikalon.com/blog/2011/Levy_flight.gif
Source:
http://www.maa.org/sites/default/files/image
s/upload_library/19/NormalCaucy.png
Fuente: Pereda, M. (2014) Random Walks and Lévy Flights. A social-science approach

29. Mobility pattern. Lévy flight motion
• 1999, theoretical work of Viswanathan et al. [1]
stated that the Lévy flight with exponent µ=2 is an
optimal search strategy in environments with scarce
resources randomly placed, that can be revisited
because they are not depleted on consumption.
• Then, it emerged the Lévy flight foraging hypothesis,
where human are believed to have evolved to follow
the Lévy flight foraging strategy because it is optimal
[2, 3].
• The Lévy flight has also applied to explain the
movement pattern of hunter-gatherer societies:
• the Dobe Ju/’hoansi living in deserted areas in Botswana
and Namibia [4].
• the Peruvian purse-seiners [5].
• the Hadza societies in the northern Tanzania [6]
Fuente: Pereda, M. (2014) Random Walks and Lévy Flights. A social-science approach

30. Spatial correlation

31. Fuente: http://ascape.sourceforge.net/manual/Section1.html

32. Latin Hypercube sampling
Fuente: https://www.sharcnet.ca/Software/Ansys/fluent/14.0/help/ans_adv/Hlp_G_ADVPDS5.html

33. Parameters Range explored
beached‐whale‐distribution  ;uniform gaussian
movement  ;random walk levy flight 
beach‐density  0.25,0.75
people‐density  0.001,0.01
prob‐beached‐whale  0.01,0.5
distance‐walked‐per‐tick  1,13
vision  2,50
signal‐range  50,100
prob‐mutation  0.01,0.1
rounds‐per‐generation  25,75
social‐capital‐vs‐meat‐sensitivity  0,1
beached‐whale‐life  0.25,0.75
history‐size  1,20
history‐past‐discount  0.5,1
marginal‐function‐alpha  1,0
cauchy‐scale  1,5
gaussian‐std‐dev  5,100

34. Results as a regression problem. CART
trees
• Decision trees are one of the most popular learning
methods commonly used for data exploration.
• One type of decision tree is called CART… classification
and regression tree.
• CART … greedy, top-down binary, recursive partitioning,
that divides feature space into sets of disjoint rectangular
regions.
• Simple model is fit in each region – majority vote for
classification, constant value for regression.
Fuente: home.etf.rs/~vm/os/dmsw/Random%20Forest.pptx

36. Results as a regression problem. Random
Forest

37. Variable importance index
• The increasing in mean of a tree (MSE) for
regression in the forest when the observed values
of this variable are randomly permuted in the OOB
samples
Fuente: Genuer, R., Poggi, J. M., & Tuleau-Malot, C. (2010). Variable selection using random forests. Pattern Recognition Letters, 31(14), 2225-2236.

38. Variable importance

39. Average cooperation and spatial
distribution of beached whales
• spatial
concentration
favours
cooperation
• positive
assortment
• vigilance
network

40. Average cooperation and movement
• public-private
discrepancy decreases
significantly
• and consequently the
abnormal levels of
cooperation reached for
low values of vision (v =
10)
• When the resource is
more abundant (Pbw =
0.2) there are more
opportunities for
defectors to find a
beached whale apart
from the group of
cooperators (Lévy-
flight8)

41. Parochialism
• Preservation of the context, e.g. continuity of interaction
patterns, as a key mechanism to foster and sustain
cooperative behaviours in the analysis of social dilemmas
[7, 8]
1. retaliation effect
2. reputation effect
3. segmentation effect

42. Conclusions
• This model allowed us to disentangle the mechanisms and conditions that promoted
cooperation (vision, reputation, mobility and stranding spatial distribution)
• Spatial concentration of beached whales pushes up cooperation from the original levels
reached by the effect of the indirect reciprocity mechanism. The cooperative behaviour
favours the emergence and preservation of informal and dynamic communities that work as
a vigilance network making defection very costly
• When agents follow Lévy flight movement, assuming that a correlation exists between this
movement type and the large average step length, the distance or effective vision at which
an agent can interact with other agents and the environment grows, which means a greater
ability to detect beached whales and more callings by cooperators and defectors
• Lévy flight, with a large average step length, promotes cooperation when beachings are
scarce. In this scenario, the higher effective vision extends the vigilance network
discouraging defectors, who have few opportunities to prosper apart from the group of
cooperators.
• If the assumed correlation between Lévy flight and the large average step length is
absent, the movement pattern itself will not have as much influence in promoting
cooperation

43. Methodological
• Agent based modelling
and Archaeology
• Agent based modelling
and Machine Learning

44. Acknowledgments
• Briz i Godino, I.,
• Izquierdo, L.R.,
• Álvarez, M.,
• Caro, J.,
• Santos, J.I.,
• Zurro, D.
• Pereda, M.

45. References
[1] Viswanathan, G. M.; Buldyrev, Sergey V.; Havlin, Shlomo; da Luz, M. G. E.; Raposo, E. P.;
Stanley, H. Eugene (28 October 1999). "Optimizing the success of random
searches". Nature 401(6756): 911–914. doi:10.1038/44831.
[2] Viswanathan, G. M., Raposo, E. P., & da Luz, M. G. E. (2008). Lévy flights and
superdiffusion in the context of biological encounters and random searches. Physics of Life
Reviews, 5(3), 133–150. doi:10.1016/j.plrev.2008.03.002
[3] Viswanathan, G. M., M. G. E. da Luz, E. P. Raposo, and H. E. Stanley, 2011, The Physics of
Foraging: An Introduction to Random Searches and Biological Encounters Cambridge
University Press.
[4] Brown, C., L. Liebovitch, and R. Glendon, 2007, Lévy Flights in Dobe Ju/'hoansi Foraging
Patterns: Human Ecology, v. 35, no. 1, p. 129-138.
[5] Bertrand, S., J. M. Burgos, F. Gerlotto, and J. Atiquipa, 2005, Lévy trajectories of Peruvian
purse-seiners as an indicator of the spatial distribution of anchovy (Engraulis ringens): ICES
Journal of Marine Science, v. 62, p. 477-482.
[6] Raichlen, D. A., B. M. Wood, A. D. Gordon, A. Z. P. Mabulla, F. W. Marlowe, and H. Pontzer,
2013, Evidence of Lévy walk foraging patterns in human hunter-gatherers: Proceedings of the
National Academy of Sciences.
[7] Bowles S, Gintis H. Persistent parochialism: trust and exclusion in ethnic networks. Journal
of Economic Behavior & Organization 2004;55: 1–23. doi: 10.1016/j.jebo.2003.06.005
[8] Bowles S, Gintis H. The Moral Economy of Communities: Structured Populations and the
Evolution of Pro-Social Norms. Evolution and Human Behavior 1998;19: 3–25. doi:
10.1016/S1090-5138(98)00015-4

46. MODELADO BASADO EN AGENTES
PARA SIMULAR EL PASADO.
COOPERACIÓN SOCIAL EN TIERRA
DEL FUEGO
#simulpast
Facultad de Informática
Universidad Complutense de Madrid
22 de abril de 2015