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Modelado basado en agentes para simular el pasado. Cooperación social en Tierra del Fuego


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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

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Modelado basado en agentes para simular el pasado. Cooperación social en Tierra del Fuego

  1. 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. 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. 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
  4. 4. “Nuestro laboratorio social”
  5. 5. Tendencias
  6. 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. 7. Contexto del proyecto Fuente:
  8. 8. Simulpast
  9. 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. 10. Los Yámana Fuente«Pueblos indigenas de Chile-ver» de Createaccount - Disponible bajo la licencia CC BY- SA 3.0 vía Wikimedia Commons - • Thomas Bridges • Martin Gusinde
  11. 11. Varamientos de cetáceos o sardinas (iacasi)
  12. 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. 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. 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. 15. Cooperation Mechanisms Fuente: Nowak, M.A. (2006) Five rules for the evolution of cooperation. Science 314(5805): 1560–1563.
  16. 16. Cooperation Mechanisms Fuente: Nowak, M.A. (2006) Five rules for the evolution of cooperation. Science 314(5805): 1560–1563.
  17. 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. 18. WWHW • People • Move • Call? • Whales
  19. 19. Reputation
  20. 20. Results
  21. 21. Model II • Mobility pattern • Resource Spatial Correlation • Parameter space exploration
  22. 22. 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: Source: 7/fractal/foto11_Brown.GIF Fuente: Pereda, M. (2014) Random Walks and Lévy Flights. A social-science approach
  23. 23. 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: Source: s/upload_library/19/NormalCaucy.png Fuente: Pereda, M. (2014) Random Walks and Lévy Flights. A social-science approach
  24. 24. 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
  25. 25. Spatial correlation
  26. 26. Fuente:
  27. 27. Latin Hypercube sampling Fuente:
  28. 28. 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    
  29. 29. 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:
  30. 30. Results as a regression problem. Random Forest
  31. 31. 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.
  32. 32. Variable importance
  33. 33. Average cooperation and spatial distribution of beached whales • spatial concentration favours cooperation • positive assortment • vigilance network
  34. 34. 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)
  35. 35. 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
  36. 36. 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
  37. 37. Methodological • Agent based modelling and Archaeology • Agent based modelling and Machine Learning
  38. 38. Acknowledgments • Briz i Godino, I., • Izquierdo, L.R., • Álvarez, M., • Caro, J., • Santos, J.I., • Zurro, D. • Pereda, M.
  39. 39. 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
  40. 40. 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