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Blame Colombus? New skeletal evidence and the paleodemography of the Americas over the millennia.

Blame Colombus? New skeletal evidence and the paleodemography of the Americas over the millennia. Fertility : regulator of demographic dynamics in the Ancient Americas paper posted at: www.hist.umn.edu/ ~rmccaa/paleodem.doc .

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Blame Colombus? New skeletal evidence and the paleodemography of the Americas over the millennia.

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  1. Blame Colombus? New skeletal evidence and the paleodemography of the Americas over the millennia. Fertility: regulator of demographic dynamics in the Ancient Americaspaper posted at: www.hist.umn.edu/ ~rmccaa/paleodem.doc Fertility: the regulator of demographic dynamics in the Ancient Americas

  2. Richard Steckel and Jerome Rose (eds.), The Backbone of History: Health and Nutrition in the Western Hemisphere (7000 BP – 1900 AD), Cambridge University Press, 2002 • Largest collection of skeletal microdata ever assembled: 12,500 skeletons, 65 sites, 7 millennia • Uniform methodology: 24 bio-archaeologists, 6 historians Fertility: the regulator of demographic dynamics in the Ancient Americas

  3. Subject:The human skeleton.Microdata:source for studying health, nutrition and demographic dynamics Fertility: the regulator of demographic dynamics in the Ancient Americas

  4. Outline, 45 slides: • 1. (10) Bioarcheological evidence on paleopathologies and height: Ancient America was no paradise • 2. (15) Paleodemography: new method • 3. (20) New findings: demographic dynamics for 3 periods:Ancient (7000 – 1500 BP)Classic (1500 – 500 BP)Historical (500 – 100 BP) Fertility: the regulator of demographic dynamics in the Ancient Americas

  5. Blame Columbus? (Title of a New York Times review of book, but not a concern of the book itself) • 1. Bioarcheological evidence on paleopathologies and height: Ancient America was no paradise • 2. Paleodemography: new method • 3. Demographic dynamics for 3 periods:Ancient (7000 – 1500 BP)Classic (1500 – 500 BP)Historical (500 – 100 BP) Fertility: the regulator of demographic dynamics in the Ancient Americas

  6. 4 measures of health and nutrition • Porotic hyperostosis • Degenerative joint disease (limbs, spine) • Dental disease • Stature Fertility: the regulator of demographic dynamics in the Ancient Americas

  7. Hard Times in Ancient Americas • Skeletal archaeology shows porotic hyperostosis as nearly universal —perhaps due to extreme dependence on corn. Fertility: the regulator of demographic dynamics in the Ancient Americas

  8. Porotic Hyperostosis: a physiological adaptation to inadequate absorption of oxygen • High frequency: 1/3 – 1/12 of adults in these communities show signs of extraordinary bone remodeling. • Worsened over time: as the transition to sedentary agriculture proceeded (1-3,000 BP), physiological conditions deteriorated. • No gendered difference: “A near complete absence of sex differentials in pathologies is surprising.” Fertility: the regulator of demographic dynamics in the Ancient Americas

  9. Degenerative joint disease (DJD) • DJD: 10-20% of adults of both sexes. • From age 20, hard, repetitive work exacted severe wear on both sexes, particularly of joints required for mobility, manipulation of objects, and carrying loads. • Genderdifferences:statisticallysignificantin DJD andcranialfractures. Fertility: the regulator of demographic dynamics in the Ancient Americas

  10. Degenerative joint disease, spine:picture worsens • Generally high levels ranging from 25 to 83% for adults from the Mesoamerican sites—a ubiquitous affliction, principally due to hard labor. • “Where the means of carrying heavy burdens is almost solely the human body, an enormous biological cost is exacted from the organism.” Fertility: the regulator of demographic dynamics in the Ancient Americas

  11. Shovel shaped incisors:genetictrait of Native Americans Fertility: the regulator of demographic dynamics in the Ancient Americas

  12. Severe dental disease was common in societies based on corn Fertility: the regulator of demographic dynamics in the Ancient Americas

  13. Stature, 3 features stand out: • 1. Males decline over time in mean height: 1 cm. per thousand years--due to worsening nutrition? • 2. Female stature constant over time even from pre-historic period. • 3. Males show decreasing stature from north (164 cm) to south (161 cm). Fertility: the regulator of demographic dynamics in the Ancient Americas

  14. Male stature declines over time: confirmed in Center and South North =165 cm “no” decline South =161 cm much decline Center=162 cm some decline All =162 cm accelerating decline Fertility: the regulator of demographic dynamics in the Ancient Americas

  15. Male stature gradient S. (15°) to N. (30°): greatest in modern times (1900-1960) 3200-1800 BP =164 cm b=-.25, r2=.12 1800-1200 BP =162 cm b=.50, r2=.36 1200-500 BP=163 cm b=.36, r2=.47 100-40 BP =159 cm b=.78, r2=.74 Females (<150 cm) little variation in space or time. Fertility: the regulator of demographic dynamics in the Ancient Americas

  16. Blame…? • 1. Bioarcheological evidence on paleopathologies and height: Ancient America was no paradise • 2. Paleodemography: new method • 3. Demographic dynamics for 3 periods:Ancient (7000 – 1500 BP)Classic (1500 – 500 BP)Historical (500 – 100 BP) Fertility: the regulator of demographic dynamics in the Ancient Americas

  17. PaleodemographyMaterials:skeletons by estimated age at deathMethods:fit estimated age distributionto stable models Fertility: the regulator of demographic dynamics in the Ancient Americas

  18. A quick lesson in model life tables (of stable populations) • Stable populations: • regardless of initial conditions • populations subjected to constant birth and death rates • will evolve to stable age and death structures, that is: • % population aged 0, 1, 2, … will be the same year-after-year as long as birth & death rates are stable • % of deaths aged 0, 1, 2, … will be the same year-after-year … Fertility: the regulator of demographic dynamics in the Ancient Americas

  19. So, for the paleodemographer… • If ancient populations were stable • If the recovered skeletons are representative of the dying population • And if the age at death of the skeletons can be estimated… • Then, we match observed skeletal age distribution with those of stable populations to derive: • Birth and death rates • Life expectancy, …even age structure Fertility: the regulator of demographic dynamics in the Ancient Americas

  20. How exactly do we do this?2 steps: 1. Materials: Age distribution of skeletons Age 0 5 10 15 20 25 30 35 40 45+ Deaths (n) 239 31 12 4 22 11 21 36 31 116 % 45.7 5.9 2.3 0.8 4.2 2.1 4.0 6.9 5.9 22.1 Cum % 45.7 51.6 53.9 54.7 58.9 61.0 65.0 71.9 77.8 100.0 • Example, Belleville, Ontario. 19th century white population—well preserved Fertility: the regulator of demographic dynamics in the Ancient Americas

  21. How exactly do we do this?2 steps: 2. Models: life tables • Coale & Demeny 1983 • 25 e0s: 20-80 years, at 2.5 year intervals • 13 GRRs: 1 – 6 girls, at various intervals • 4 Regions: North, South, East, West • Total: 25x13x4=1300 Fertility: the regulator of demographic dynamics in the Ancient Americas

  22. % Population at age Model West Females level 2,GRRs 0.8 – 6e0 = 22.5 years Cummulative % • Statistics: • Population at/to age % deaths at age • Deaths at/to age • 18 stats for each GRR (see separate pages for other e0s and regions) Cummulative % Other stats Fertility: the regulator of demographic dynamics in the Ancient Americas

  23. e0=22.5 e0=52.5 or mortality (between sheets)? Question: Are age structures of dying determined by fertility (within a sheet) or mortality (between sheets)? Between (mortality)? Fertility: the regulator of demographic dynamics in the Ancient Americas Answer: contrary to common sense, fertility!!!

  24. Fertility effects are big GRR =2, 3, 4, 5, 6; e0 = 20 Fertility: the regulator of demographic dynamics in the Ancient Americas

  25. Mortality effects are smallexcept at young (< 15) and old ages (60+) Fig. 2. Mortality offers a small target GRR = 3; e0 = 20, 30, 40, 50 Fertility: the regulator of demographic dynamics in the Ancient Americas

  26. GRR = 2, 3, 4, 5, 6e0=20 GRR = 3e0=20, 30, 40, 50 GRR = 2, 3, 4, 5, 6e0=50 GRR = 4e0=20, 30, 40, 50 Fertility: the regulator of demographic dynamics in the Ancient Americas

  27. Three recent advances in paleodemography: • Fertility has stronger effects on age distributions than mortality. • Proportional hazard models are more robust than simple percentages. • Fitting observed skeletal distributions to stable populations yield valuable demographic insights. Fertility: the regulator of demographic dynamics in the Ancient Americas

  28. Four innovations here • Use only “best” age data: ages 5-45 • Fit all possible models:GRR (gross reproduction ratio) = 2-6 daughterse0(life expectancy at birth) = 20-50 years • Consider range of good fits, instead of only “best fit”—all “pretty good” fits • Calibrate paleodemographic results against historical demography—see next figure Fertility: the regulator of demographic dynamics in the Ancient Americas

  29. Calibrating method: skeletal data for 19th century Belleville, Ontario Fertility: the regulator of demographic dynamics in the Ancient Americas

  30. Fertility: the regulator of demographic dynamics in the Ancient Americas

  31. Calibration of life expectancy, e0 (Belleville)* • Conventional paleodemography: 20.8 years (MAD, “mean age at death”) • PH models, using best age data, pretty good fits, GRR = 3.16, growth rate = 2%:36 years (see table 4.1) • Historical data (parish books, census)36.5 years *thanks to an anonymous reviewer for the idea of calibrating the method using Belleville. Fertility: the regulator of demographic dynamics in the Ancient Americas

  32. Blame…? • 1. Bioarcheological evidence on paleopathologies and height: Ancient America was no paradise • 2. Paleodemography: new method • 3. Demographic dynamics for 3 periods:Ancient (7000 – 1500 BP)Classic (1500 – 500 BP)Historical (1500 AD – 1900) Fertility: the regulator of demographic dynamics in the Ancient Americas

  33. Paleodemography: new methods, surprising results: Fertility, the key • Fertility: an important regulator of American demographic dynamics • Lowest fertility: ancient times (1500+ BP), GRR=~2.2 • Higher fertility: middle period (1500BP –1500AD), GRR=~2.9 • Highest fertility: domesticated animals (horse, Plains Indians, 1500 AD-1900), GRR=3.2 • Last five hundred years: large ethnic differentials, GRRNative Americans: 2.8-2.9African Americans: 3.1-3.3European Americans: 2.4-2.6 Fertility: the regulator of demographic dynamics in the Ancient Americas

  34. Fertility: the regulator of demographic dynamics in the Ancient Americas

  35. Fertility: the regulator of demographic dynamics in the Ancient Americas

  36. Fertility: the regulator of demographic dynamics in the Ancient Americas

  37. Paleodemography: new methods, surprising results: Mortality (pooled) • Life expectancy estimates, e0: contingent upon a good estimate of growth rate • Highest e0: ancient times (1500+ BP), ~34 years • Lowest e0: middle period (1500-500), ~23 years • Modern: large ethnic differentials in e0Native Americans: e0=~ 22-23 yearsAfrican Americans: e0=~ 21-29 yearsEuropean Americans: e0=~ 30-36 years Fertility: the regulator of demographic dynamics in the Ancient Americas

  38. Three conclusions • Great variations in fertility • Ancient times, • low pressure demographic regime: • fertility was a brake on population growth • Classic times, • high pressure demographic system: • higher fertility, low life expectancy • mortality was the brake on pop. growth Fertility: the regulator of demographic dynamics in the Ancient Americas

  39. Three conclusions 2. Agriculture was the “caboose” of demographic change, not the “engine” • Agriculture seems to have evolved as a response to demographic pressure • Rather than propelling demographic transformations. • Why? Because in classic times demographic transformations occurred in all settlement types. Fertility: the regulator of demographic dynamics in the Ancient Americas

  40. Three conclusions 3. Modern period: fundamental demography of native peoples did not change with the clash of biospheres • Paleodemographic method is insensitive to demographic catastrophe—unless a mass grave is found • Underlying fundamentals persisted for almost a thousand years (til 1800) Fertility: the regulator of demographic dynamics in the Ancient Americas

  41. Postscript: Blame Colombus? • Demographic catastrophe was real—the debate is about magnitude and cause(s) • Magnitude: extinction for many smaller populations (e.g, Tainos); 1/3-3/4 loss for larger populations (Aztecs). • Cause(s): the great debate—disease? War/pacification/exploitation? Both? • Varied place-to-place: Hispaniola: exploitation, not disease… Fertility: the regulator of demographic dynamics in the Ancient Americas

  42. Blame Colombus? Hispaniola, certainly!! Case of Hispaniola, see: Bartolome de Las Casas, Brief Account of the Destruction of the Indies (1596), or Massimo Livi-Bacci, “Return to Hispaniola”, February 2003, Hispanic American Historical Review Fertility: the regulator of demographic dynamics in the Ancient Americas

  43. Blame Colombus? Hispaniola, certainly!! Disease?: • First smallpox epidemic, 1518 (25 years after contact, colonization). • Evidence of other introduced diseases in first decades is scant (non-existent?). • Malaria and Yellow fever (cited by Wilford, NYT): 17th- 18th centuries Fertility: the regulator of demographic dynamics in the Ancient Americas

  44. Blame Colombus? Hispaniola, certainly!! Exploitation?: ML-B: “tribute imposed by Colon at the end of 1495 to the caciques of the ‘pacified’ Tainos: every native of 14 years or more was required to pay every three months one Flanders hawk’s bell full of gold…” Fertility: the regulator of demographic dynamics in the Ancient Americas

  45. Blame Colombus? Hispaniola, certainly!! Exploitation?: • Fragile communities—”congregated” • Little agricultural surplus • All “work” devoted to food production • Unaccustomed to forced labor for building, gold mining. • Insatiable demand by Christians for gold, slaves, servants, … sex Fertility: the regulator of demographic dynamics in the Ancient Americas

  46. Demographic catastrophe and its causes: viruses, Black Legend and the social context of epidemics (Mexico) Alonso de Zorita (~1565): “...and it is certain that from the day that D. Hernando Cortes, the Marquis del Valle, entered this land...the natives suffered many deaths, and many terrible dealings, robberies and oppressions were inflicted on them, taking advantage of their persons and their lands, without order, weight nor measure; ...the people diminished in great number, as much due to excessive taxes and mistreatment, as to illness and smallpox, such that now a very great and notable fraction of the people are gone, and especially in the hot country.” Fertility: the regulator of demographic dynamics in the Ancient Americas

  47. Blame Colombus…??The debate continues… see next issues of Revista de Indias and Hispanic American Historical Review Fertility: the regulator of demographic dynamics in the Ancient Americas

  48. Thank you* * * * * *paper posted:www.hist.umn.edu/~rmccaa/paleodem.doc others:Health & nutrition: /mxbioarc.docAztec household & family: /nacolhist.htmSmallpox & catastrophe: /vircatas/vir6.htm Fertility: the regulator of demographic dynamics in the Ancient Americas

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