Reproduction process in Hunter-fisher-gatherers: Multi Agents Simulation

1. Reproduction process in Hunter-fisher-gatherers: Multi Agents Simulation J.Estévez Universitat Autònoma de Barcelona A.VilaSpanish National Research Council (CSIC) IMF- CSIC

2. 1. POSTING THE QUESTION

3. EXTANT HUMAN SPECIES REPRODUCTIVE POTENTIAL IS VERY HIGH

4. The exemple of the huterites The ANNUAL GROWING RATE of Huterites Implies that they could completelly fill up the whole African continent with a density of one person per square meter in just 750 years 750 YEARS 100 YEARS

5. Social normsthatemphasizethemanagement of reproduction • Verydifferentgrowingrates and sometimesanimpressivecapacityforrecovery The PREHISTORY of HUNTER-GATHERER SHOWS: • Long term demographic stability EXTANCT HUNTER-GATHERER HAVE:

6. Annual grow +0.7% (Ache), –0.2% (Agta), +1.3% (Hadza) +0.26% (!Kung) The mean for agta women was 7 live children a 26% could die before 15. The maximum potential fertility was 14,5. 1990 COAST SALISH POPULATION RECOVERY 1930

7. MODERN HGshow very different growing rates and sometimes an impressive capacity of recovery

8. What is “NATURAL” is the ABILITY to procreate, but NOT the FACT of PROCREATE. The set of variables on which depends natural fertility can be and are indeed socially modified.

9. THE “FACT” The process of social reproduction is regulated by SOCIAL NORMS which direct all parts of the process: prior to pregnancy, childbirth, feeding and care, education… Each part involves labor (social relationships), products, spaces, etc. like any other process.

10. Demographicgrow can be managed (reduced) by: • Controllingintercourse • Increasingbiasedfemaleinfantilemortality HOW Demographic grow can be managed (reduced) by: • Controlling intercourse • regulating the availability of fertile women. • reducing contact between men and women. • lowering the fertility of women (food taboos, prolonged breast-feeding…) • with norms of celibacy and abstinence • with frightening morals and rituals • … • Demographicgrow can be managed (reduced) by: • INTENTIONALLY increasingmortality of infantile. • 48% of thesocietiesmanaged in HRAFS recognizeinfanticideagainst a 11% that do notpracticeit. • Infanticideismanagedmostlybyparents (mothers) .

11. Simulations show thegreatimpact of suchpractices

12. HominidaeBiologicaldynamics CO-EVOLUTIONATED DISEASES DEPREDATION STARVATION CARRYING CAPACITY

13. HUMAN SOCIAL dynamics MIGRATION CO-EVOLUTIONATED ILLNESS FIRE-TECNOLOGY MUTUAL AID SHARING DEPREDATION STARVATION TECNOLOGICAL DEVELOPMENT CARRYING CAPACITY

14. HUMAN SOCIAL dynamics EFFORT INVESTMENT IN SOCIAL NORMS: STRUCTURAL VIOLENCE: SEXUAL RESTRICTIONS DIVISION OF LABOR INEQUALITY REDISTRIBUTED- PUNISHMENT INFANTICIDE HOMICIDE-WAR MIGRATION INTENSIFICATION SOCIAL STRATEGIES CARRYING CAPACITY

15. Modern HG Societies throughout history will have learned from their accumulated experience and have developed strategies and norms with which they have successfully managed their reproduction and sustainability.

16. Ourthesisis: • Through the sexual division of labor. • Subsequently asymetrybetweenmen and women can be easelystablished. • Itisalsoeasytojustificateadvoquingbiologicaldiferences. • Thus division of labor is not a biological bias but the historical consequence of reproductive strategies to manage the demographic variable in those societies How was it implemented?

17. It may have been the functional social alternative at a “given” moment It is clearly evident in most CR ethnographic societies.

18. are now archaeological questions. This is the aim of our research When, how and why in every case

19. WHAT’ S OUR AIM We propose first to verify the thesis that -The axis that determines the development of HG societies depends on reproduction and -that the control is exercised a decisive through social norms.-

20. Reproduction processes are ultimately dependent on exposure to fertilization.    This variable is fully regulated socially. • The social relations of reproduction and how they are articulated are the basis for social explanation. • We can simulate its operation by • - Multiagent Systems. • Significant sample constituted by a • broad spectrum of ethnographic societies.

21. Ethnoarchaeology • to observe the realization of these rules in a archaeological record. • Agent based simulation THEREFORE

22. 1986-2005 Ethnoarchaeology of yamana and sel’knam sites 2008-2010: Mechanisms of Autoregulation and Social Control generating Social Norms. 2011- 2014: Ethnoarchaeological Approach to Reproduction in H-Gatherer Societies.

23. ANALYSIS OF 4 ETNOGRAPHIC CASE STUDIES • SW ALASKA (Inupiat) • NW coast of America (Coast Salish) • Fueguian canoe people(Yamana) • Terrestrial HG of T. Fuego (Selknam ) • Yolgnu of North Australia Based mainly on the earliest ethnographic accounts

24. Simulation of the effect of social norms on the reproduction of HG groups: • Fueguian • Coast Salish • Yolnu Basedmainlyonthefirstethnographicaccounts M.A. SIMULATION

26. Schematizingthelifecourse of men and women • Extracting and standartizingthenorms and rules involved and affectingthereproductionrates. • Simulatingtheeffect of normsonsocieties of agentswithbiological and reputation(prestige and punishment) impulses. HOW

27. 1ST STEP- SCHEMATIZING

28. 3 Sexual segregation ENVIRONMENT HAZARDS infant boy 4 marriage pairing paired single Ciexaus Adolescent fertile married birth widowed Kina +2 polygammy divorce divorced disease accident death Yamana boy

29. 2 4 Sexual segregation ENVIRONMENT HAZARDS infant boy 7 pairing paired Adolescent fertile single Hain widowing birth widowed +1 marriage married divorce divorced polygammy disease accident Abandonment death Selk’nam boy

30. 3 Sexual segregation ENVIRONMENT HAZARDS infant girl 4 pairing paired Ciexaus Adolescent menarche single marriage married ±13 Fertility rate embarrace widowing widowed abortion PREGNANT birth disease accident death Yamana girl

31. 2 4 Sexual segregation ENVIRONMENT HAZARDS infant girl 7 pairing paired Adolescent menarche single ±13 Fertility rate embarrace abortion PREGNANT widowing widowed birth marriage married divorce divorced disease accident Abandonment death Selk’nam girl

32. EVALUATION OF THE EFFECTIVENESS OF SOCIAL NORMS FOR THE MANAGEMENT OF REPRODUCTION: 2. OBJECTIVE Demographic growth can be managed (reduced) by: • Controlling intercourse • regulating the availability of fertile women. • reducing contact between men and women. • lowering the fertility of women (food taboos, prolonged breast-feeding…) • with norms of celibacy and abstinence • with frightening morals and rituals • … • Increasing biased female infantile mortality

33. 4. METHODOLOGY:AGENT-BASED SIMULATION TO TEST THE EFFECTS OF SOCIAL NORMS ON DEMOGRAPHY“Agent -based models, simulated over time, can elucidate the relationship between individual or group (human) decisions and the social structures which both results from and constrain those decisions”Cathy A. Small (2000). THE AIM IS NOT TO SIMULATE A WHOLE SOCIAL SYSTEM BUT TO TEST THE EFFECT OF THE DIFFERENT PARAMETERS INVOLVED

34. Ethnologicalstudies Informationaboutthe social normsandbehaviour Extensivelist of social norms listof relevant social norms Demografic and biologialreproductionstudies Individuals’ biological general behaviour Normative behaviour List of generalized social norms Agent simulation system Current climate, biological and ethological studies Environment & resources Information about the environment and resources Paleontological studies

35. Biologicallaws(community) Agefertilitydistribution, Agedeadrate Engineprogram(Java) Community: agentslist Community: new agentslist Current Individual AgentAttributes Individual AgentAttributes Environment, family, name, sex, parents, genes XY, health, libido, boldness, rules-respect , reputation, social status, biological status, Capsules Biological laws ponderation: i.e.: breasting time ammenorrea, accident rate by age… Stats: mortality rate, fecundity, health rates, norm acomplishment rate, deliveries, infanticides, number of children… Norms Preconditions (trigger) Limitations consequences

36. OUTPUTS

37. OUTPUTS INDIVIDUAL’S STORIES LINEAGES

38. YAMANA NORMS SIMULATION • Versus • NO restrictions –or- MORE restrictive NORMS • POLYGAMY • INFANTICIDE BECAUSE LOW HEALTH • FEMALE INFANTICIDE BECAUSE EXCESS GIRLS 5. EXAMPLE AND TESTED PARAMETERS: USING YAMANA NORMS

39. EMERGING PATTERNS NO SOCIAL RULES (300 years)mean of growthindexfor 10 years There are biological cycles of 30 aprox. years

40. RESULTS global population (after 100 years x 30 essays) No infanticide monogamy No infanticide, no restrictions poligamy Infanticide 4th girl Infanticide 3th girl Maximal restrictions

41. Mean for 10 years growing rate

42. Mean for 10 years growing rate

43. Num. of women with n children

44. Num. of women with n children

45. DEMOGRAPHICPATTERNS Mean NUM. of chidren born & alive ABSOLUTE NUM. of males & females

46. In a small population a catastrophic growing rate is hard to perceive along 100 years. Thus REPRODUCTION IS VERY DIFFICULT TO MANAGE consciously and strategies will arise The more restrictive rules the less variability along the experiments. Some more conclusions

47. Polygyny is an effective method to reduce reproduction. Infanticide is the last resort strategy to manage efficiently demographic growing potential of modern humans but the most effective- Restrictive social norms and structural violence (for instance, female infanticide) would require of an ideological justification. Some more conclusions

48. HG do not consciously attempt to create an optimal pattern of norms for sustainability in reproduction. Nonetheless, such patterns occur and are typical, but how did they get the solution? We are still working to test our answer to this question. Final remark

49. These are some results of te Reseach Project HAR2011-24356 ETHNO-ARCHAEOLOGICAL ANALYSIS OF REPRODUCTION IN HUNTER-GATHERER SOCIETIES With the participation of M.Gándara (INAH- Mexico), I.Davidson (UNE- Australia), C.Grier (WSU- USA), M.Pérez (ESPOL- Equador), J.Salius (UAB), M.Blake UBC- Canada), E.Mansur (CONICET- Argentina), Alfredo Prieto (UdM-Chile).