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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
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

slide2
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

subject the human skeleton microdata source for studying health nutrition and demographic dynamics
Subject:The human skeleton.Microdata:source for studying health, nutrition and demographic dynamics

Fertility: the regulator of demographic dynamics in the Ancient Americas

outline 45 slides
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

blame columbus title of a new york times review of book but not a concern of the book itself
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

4 measures of health and nutrition
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

hard times in ancient americas
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

porotic hyperostosis a physiological adaptation to inadequate absorption of oxygen
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

degenerative joint disease djd
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

degenerative joint disease spine picture worsens
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

shovel shaped incisors genetic trait of native americans
Shovel shaped incisors:genetictrait of Native Americans

Fertility: the regulator of demographic dynamics in the Ancient Americas

severe dental disease was common in societies based on corn
Severe dental disease was common in societies based on corn

Fertility: the regulator of demographic dynamics in the Ancient Americas

stature 3 features stand out
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

male stature declines over time confirmed in center and south
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

male stature gradient s 15 to n 30 greatest in modern times 1900 1960
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

blame
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

slide17
PaleodemographyMaterials:skeletons by estimated age at deathMethods:fit estimated age distributionto stable models

Fertility: the regulator of demographic dynamics in the Ancient Americas

a quick lesson in model life tables of stable populations
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

so for the paleodemographer
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

how exactly do we do this 2 steps 1 materials age distribution of skeletons
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

how exactly do we do this 2 steps 2 models life tables
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

model west females level 2 grrs 0 8 6 e 0 22 5 years
% Population at ageModel 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

slide23
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!!!

slide24
Fertility effects are big

GRR =2, 3, 4, 5, 6; e0 = 20

Fertility: the regulator of demographic dynamics in the Ancient Americas

fig 2 mortality offers a small target
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

slide26
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

three recent advances in paleodemography
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

four innovations here
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

calibrating method skeletal data for 19 th century belleville ontario

Calibrating method: skeletal data for 19th century Belleville, Ontario

Fertility: the regulator of demographic dynamics in the Ancient Americas

calibration of life expectancy e 0 belleville
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

blame32
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

slide33
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

slide37
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

three conclusions
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

three conclusions39
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

three conclusions40
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

postscript blame colombus
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

blame colombus hispaniola certainly
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

blame colombus hispaniola certainly43
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

blame colombus hispaniola certainly44
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

blame colombus hispaniola certainly45
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

slide46
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

blame colombus the debate continues
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

thank you paper posted www hist umn edu rmccaa paleodem doc
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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