MODELADO BASADO EN AGENTES PARA SIMULAR EL PASADO. COOPERACIÓN SOCIAL EN TIERRA DEL FUEGO

#simulpastFacultad de InformáticaUniversidad Complutense de Madrid22 de abril de 2015

Aplicaciones de los agentes

Aplic

acio

nes

de lo

s ag

ente

s

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

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

“Nuestro laboratorio social”

Tendencias

Estructura de la presentación

1. Contexto del proyecto2. El caso de estudio3. El modelo I4. Resultados5. El modelo II6. Resultados7. Conclusiones

Contexto del proyecto

Fuente: www.Simulpast.net

Simulpast

• 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

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

Varamientos de cetáceos o sardinas (iacasi)

• “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”.

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

Etnoarchaeological record

1. References about beached whales are frequent and detailed

2. Songs to bring them to coast3. Festive social occasion4. Blubber and mushrooms were the only edible resources

that people stored5. Social norms punished people that did not notify the

community of the presence of a beached whale

Cooperation Mechanisms

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

Cooperation Mechanisms

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

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

WWHW• People

• Move• Call?

• Whales

Reputation

Results

Model II

• Mobility pattern

• Resource Spatial Correlation

• Parameter space exploration

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/2002/37/fractal/foto11_Brown.GIF

Fuente: Pereda, M. (2014) Random Walks and Lévy Flights. A social-science approach

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/images/upload_library/19/NormalCaucy.png

Fuente: Pereda, M. (2014) Random Walks and Lévy Flights. A social-science approach

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

Spatial correlation

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

Latin Hypercube sampling

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

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  

 

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

Results as a regression problem. RandomForest

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.

Variable importance

Average cooperation and spatial distribution of beached whales

• spatialconcentrationfavourscooperation

• positive assortment

• vigilance network

Average cooperation and movement• public-private

discrepancy decreasessignificantly

• 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)

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 effect2. reputation effect3. segmentation effect

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 behaviourfavours 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

Methodological

• Agent based modellingand Archaeology

• Agent based modellingand Machine Learning

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

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

MODELADO BASADO EN AGENTES PARA SIMULAR EL PASADO. COOPERACIÓN SOCIAL EN TIERRA DEL FUEGO

#simulpastFacultad de InformáticaUniversidad Complutense de Madrid22 de abril de 2015