Title: Blame Colombus? New skeletal evidence and the paleodemography of the Americas over the millennia.
1Blame 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
2Richard 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
3SubjectThe human skeleton.Microdatasource
for studying health, nutrition and demographic
dynamics
4Outline, 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
periodsAncient (7000 1500 BP)Classic (1500
500 BP)Historical (500 100 BP)
5Blame 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 periodsAncient
(7000 1500 BP)Classic (1500 500
BP)Historical (500 100 BP)
64 measures of health and nutrition
- Porotic hyperostosis
- Degenerative joint disease (limbs, spine)
- Dental disease
- Stature
7Hard Times in Ancient Americas
- Skeletal archaeology shows porotic hyperostosis
as nearly universal perhaps due to extreme
dependence on corn.
8Porotic 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.
9Degenerative 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. - Genderdifferencesstatisticallysignificantin
DJD andcranialfractures.
10Degenerative joint disease, spinepicture
worsens
- Generally high levels ranging from 25 to 83 for
adults from the Mesoamerican sitesa 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.
11Shovel shaped incisorsgenetictrait of Native
Americans
12Severe dental disease was common in societies
based on corn
13Stature, 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).
14Male 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
15Male 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 (lt150 cm) little variation in space or
time.
16Blame?
- 1. Bioarcheological evidence on paleopathologies
and height Ancient America was no paradise - 2. Paleodemography new method
- 3. Demographic dynamics for 3 periodsAncient
(7000 1500 BP)Classic (1500 500
BP)Historical (500 100 BP)
17PaleodemographyMaterialsskeletons by estimated
age at deathMethodsfit estimated age
distributionto stable models
18A 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
19So, 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
20How exactly do we do this?2 steps 1.
Materials Age distribution of skeletons
- Example, Belleville, Ontario. 19th century white
populationwell preserved
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
21How 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 25x13x41300
22Model West Females level 2,GRRs 0.8 6 e0
22.5 years
Population at age
- Statistics
- Population at/to age
Cummulative
deaths at age
- 18 stats for each GRR (see separate pages for
other e0s and regions)
Cummulative
Other stats
23- Question Are age structures of dying
determined by fertility (within a sheet) or
mortality (between sheets)?
or mortality (between sheets)?
Between (mortality)?
Answer contrary to common sense, fertility!!!
24Fertility effects are big
GRR 2 , 3, 4, 5, 6 e0 20
25Fig. 2. Mortality offers a small target
Mortality effects are smallexcept at young (lt
15) and old ages (60)
GRR 3 e0 20, 30, 40, 50
26GRR 2, 3, 4, 5, 6e020
GRR 3e020, 30, 40, 50
GRR 2, 3, 4, 5, 6e050
GRR 4e020, 30, 40, 50
27Three 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.
28Four innovations here
- Use only best age data ages 5-45
- Fit all possible modelsGRR (gross reproduction
ratio) 2-6 daughterse0 (life expectancy at
birth) 20-50 years - Consider range of good fits, instead of only
best fitall pretty good fits - Calibrate paleodemographic results against
historical demographysee next figure
29Calibrating method skeletal data for 19th
century Belleville, Ontario
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31Calibration 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 236 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.
32Blame?
- 1. Bioarcheological evidence on paleopathologies
and height Ancient America was no paradise - 2. Paleodemography new method
- 3. Demographic dynamics for 3 periodsAncient
(7000 1500 BP)Classic (1500 500
BP)Historical (1500 AD 1900)
33Paleodemography new methods, surprising
results Fertility, the key
- Fertility an important regulator of American
demographic dynamics - Lowest fertility ancient times (1500 BP),
GRR2.2 - Higher fertility middle period (1500BP
1500AD), GRR2.9 - Highest fertility domesticated animals (horse,
Plains Indians, 1500 AD-1900), GRR3.2 - Last five hundred years large ethnic
differentials, GRRNative Americans
2.8-2.9African Americans 3.1-3.3European
Americans 2.4-2.6
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35(No Transcript)
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37Paleodemography 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 e0 Native
Americans e0 22-23 yearsAfrican Americans
e0 21-29 yearsEuropean Americans e0 30-36
years
38Three 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
39Three 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.
40Three conclusions
- 3. Modern period fundamental demography of
native peoples did not change with the clash of
biospheres - Paleodemographic method is insensitive to
demographic catastropheunless a mass grave is
found - Underlying fundamentals persisted for almost a
thousand years (til 1800)
41Postscript Blame Colombus?
- Demographic catastrophe was realthe 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 debatedisease?
War/pacification/exploitation? Both? - Varied place-to-place Hispaniola
exploitation, not disease
42Blame 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
43Blame 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
44Blame 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 hawks bell
full of gold
45Blame Colombus? Hispaniola, certainly!!
- Exploitation?
- Fragile communitiescongregated
- 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
46Demographic 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.
47Blame Colombus??The debate continues
see next issues of Revista de Indias and
Hispanic American Historical Review
48Thank you paper postedwww.hist.umn
.edu/rmccaa/paleodem.doc
othersHealth nutrition /mxbioarc.docAztec
household family /nacolhist.htmSmallpox
catastrophe /vircatas/vir6.htm