anth 342 chapter 4
TRANSCRIPT
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Chapter 4: Demography
aka Population Studies or PopulationScience
The study of human populations Size
Composition
Distribution Causes and consequences of changes in those
characteristics
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Demography is interdisciplinary
Many factors impact population
Demographers can be trained in
Sociology
Economics
Biology
Geography
History
Health sciences
ANTHROPOLOGY
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Population measures
Fertility
Mortality
Migration
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Fertility
Number of births that occur to an individual
or in a population
Worldwide fertility ranges from 1.3 in
Spain to 7.4 in Niger
US fertility is approx. 2.1
Hutterite fertility was 12
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Intermediate variables affecting
fertility Davis and Blake 1956
Fecundity
Ability to have intercourse, conceive, and carry to term Sexual unions
Formation and dissolution, age at first intercourse,
proportion of women in unions, time spent outside a
union, coital frequency, celibacy, temporary separations
Birth control
Contraceptive use, sterilization, abortion
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Industrialized countries
Contraceptive use and abortion most
important factors
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Developing countries
Infecundity due to STDs, HIV/AIDS,
lactational amenoreah (Interbirth interval),
and postpartum abstinence (postpartumtaboo) most important factors
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Fertility patterns
This implies that people in industrialized
countries want to limit their fertility and
people in developing countries are limitedby exogenous factors
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Measures of fertility
Period rates
Cohort rates
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Period rates
Total fertility rate (TFR)
Average number of children born per women in apopulation
Replacement level fertility Fertility required to keep a population at its current
level
Crude birth rate (CBR)
Number of births per 1000 population General fertility rate (GFR)
Number of births per woman
Net reproductive rate (R0)
Current births plus expected births (RV)
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Period rates contd.
Most of these measures focus on women
15-49 years old. Why?
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Cohort rates
Completed fertility rate (CFR) or completed
family size (CFS)
Number of live births to a woman who hascompleted reproduction (menopause)
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Variation in fertility
Within a society or political entity
Between a society or political entity
Between men and women in the same
society
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Mortality: Death
Usually measured as
Crude death rate: number of deaths per
1,000 population
Worldwide range from 2 in the Persian Gulf
states to 30 in civil war torn Sierra Leone
n US about 9 per 1,000
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Death rate
Highly influence by age-structure of the
population.
Where a higher percentage of thepopulation is older, death rates tend to be
higher
What about the effect of HIV/AIDS inrelation to the age-specific death rate?
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Variation in mortality
Age
Sex
Socioeconomic status
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Migration
Movement of people into or out of a
specific geographic area
Most variable of the agents of demographicchange
Difficult to measure due to lack of reporting
and monitoring
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Types of migration
In-migration (immigration)
Out-migration (emigration)
International vs. internal
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Net migration
Difference between in- and out-migration
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Variation in migration
Age
Young adults, life cycle changes
Gender In Africa males migrate, in much of Asia and LatinAmerica females migrate
Education
Extremesboth very poor and very wealthy migrate Socioeconomic status
Depends on the type of job
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International migrants
Major destinations for immigrants
US, Australia, Canada, European Community,
Israel
Often motivated by economic hardship,
war, political instability
Chain migration Choice of destination determined by presence
of social or kin network
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Variation in international
migration Age
Young adults
Gender Same as for internal migration
Education
Educated, often professionals Socioeconomic status
Higher than those who stay behind
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Population size and growth
Rate of natural increase
Crude birth rate minus crude death rate
In USA (1997) this was 14.6-8.6=6.0 (0.6%) Worldwide this was 23.1-9.0=14.0 (1.4%)
Growth rate
Rate of natural increase+net migration
A growth rate of 1% means a population will
double in 70 years
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At present growth rates
Worlds population will double in 50 years
If the growth rate doubles to 2.8%, the
worlds population will double in 25 years
Conversely if the growth rate decreases by
half to 0.7%, the doubling would occur in
100 years
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Demographic balancing equation
Shows the roles of fertility, mortality, and
migration in population change
Population =Birthsdeaths +immigrants-emigrants
Used in population projection
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Population projection
Demographers can project population based
on current rates of fertility, mortality, and
migration Also can use estimated future rates
Projections lose accuracy quickly as the
projected time increases since it is difficultto know how demographic characters will
be affected by variables in the future
US hit 300,000,000 on Tuesday at ~7:30am
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Population composition
The aggregation of individual demographiccharacteristics on a population level
Population pyramids
Age sex composition
Four shapes:
Pyramidalhigh growth
Rectangularslow growth
Ovaldecline
HourglassAIDS driven decline
US Census International Population Pyramid
Projections
http://www.census.gov/ipc/www/idbpyr.htmlhttp://www.census.gov/ipc/www/idbpyr.htmlhttp://www.census.gov/ipc/www/idbpyr.htmlhttp://www.census.gov/ipc/www/idbpyr.html -
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Other components
Sex
Race
Ethnicity
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Race
Race as a classification has come under great fire
There may be a genetic or biological component to
race, but in general it is a subjective classificationwhich varies greatly depending on time and place.
For instance, slaves in the US could have only
one-sixteenth African ancestry
Today in the US this subjective classification
continues
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Race may be useful
It gives us some idea of who might be
subject to discrimination
Ethnicity refers to linguistic and/or culturalheritage and should not be confused with
race
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Population distribution
Worldwide population distribution is
shifting to developing countries due to
higher fertility Both in the USA and worldwide,
urbanization is a critical influence on
population distribution
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How many people can the earth
support? Carrying capacity of the eartharound 10
billion (Cohen 1995)
When will the earth reach 10 billion atcurrent rates of growth?
Around 2035
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Demographic Transitions
Three types of demographic transitions
Fertility
Mortality
Health (also called Epidemiologic)
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Why are demographic transitions
important? The combined effect of demographic
transitions results in very low population
growth The age structure of the population becomes
older
This has effects on economy, healthinstitutions, educational institutions
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Theories of fertility transitions
Classical demographic theory
Economic models
Social models
Evolutionary models
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Classical transition theory
Industrialization and modernization led to initialhigher fertility due to improved health care andhigher quality and more reliable food supply
Because pre-industrial societies had highmortality, higher fertility was necessary for thosesocieties to survive
Fertility could only be expected to fall due to the
effects of industrialization: higher survival,individualism, consumerism, mobile urban
populations, lessening of familial ties, and declineof fatalism
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Classical transition theory contd.
Three phases of fertility decline
Inicipient decline--widespread fertility control,
heavy industrialization Transitional growth--low mortality but high
fertility, industrializing
High growth potentialhigh mortality and highfertility, very low industrialization
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Economic explanations
Applied principles of microeconomics to
childrenanother normal good
Differ in whether desire for children is establishedearly in life or is based on current conditions
Supply and demand: Children are more in demand
where they are less expensive
Economic value of children depends on context of
subsistence economy.
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Social explanations
Post-modernist interpretation
Ideational change is major motivator of
fertility transitions
Uses diffusion theory
Ideas about the number of children to have
follow linguistic boundaries and diffuse fromelites and centers of power to the hinterlands
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Evolutionary perspectives
Humans like other organisms evolved in thecontext of fitness maximization
Maximizing genetic representation in succeeding
generations
Human lifestyles vary widely and may show greatdivergence from the lifestyle in which humanreproductive psychology evolved
We can still understand reproductive behavior in thepresent as the manifestation of evolved psychologicalmechanisms
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These perspectives differ in two
related aspects Theory of motivation
Are people motivated by the uptake of
culturally specific roles or by their self-interest? Acquisition and utilization of information
Do people pattern their fertility after some
cultural norm or is fertility a response toenvironmental/economic conditions?
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Cost/value of children
Biologists (Trivers), demographers
(Caldwell), and economists (Becker) have
all independently recognized thatoffsprings ability to provision themselves
are important factors in determining
parental fertility
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Agriculture
Cultivation and herd animals
Domestication
Occurred worldwide about 12,000 years ago Mesopotamia
Levant
China
Indus valley
Mesoamerica
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Effects of agriculture
Agriculture changes time allocation in relation tosubsistence pattern
Affects all age-sex groups
Leads to effects of sedentization
Changes diet composition
Increase in simple carbohydrates such as starch andsugar
Increased use of animal fat
Use of dairy products
Potential serious consequences in micronutrient balance
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Epidemiological transition
Increasing health issues related to
agriculture and sedentism
Diet led to vitamin/mineral deficiency insome places due to heavy reliance on one
staple grain
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Demographic transition
Agriculture appears to be related to
substantial increases in fertility and possible
decreases in mortality Fertility change is due partly to diet change
but also is strongly related to changes in
time allocation and the benefits ofsedentism
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Social consequences
Population concentration
Storage of resources
Power differentials
All led to complex societies
Cities
Social stratification
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Transition
Nomadic hunter gatherers subsisted on
widely varied diet including grasses, fruits,
roots and tubers, mammals, birds, and fish Small groups used seasonal camps
Population density 2-3 person/square mile
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Transition cont.
Maize agriculture was introduced before 1050
Evidence
Broken hoes
Maize in refuse heaps
Large settlements
Largest had 1000 permanent inhabitants
Continual occupation
Population density increased to 25 persons/squaremile
http://www.museum.state.il.us/RiverWeb/landings/Ambot/prehistory/mississippian/economy/subsistence.htmlhttp://www.museum.state.il.us/RiverWeb/landings/Ambot/prehistory/archives/images/economy/pages/ptecon14clr2.htmlhttp://www.museum.state.il.us/RiverWeb/landings/Ambot/prehistory/mississippian/economy/farming.htmlhttp://www.museum.state.il.us/RiverWeb/landings/Ambot/prehistory/mississippian/economy/farming.htmlhttp://www.museum.state.il.us/RiverWeb/landings/Ambot/prehistory/archives/images/economy/pages/ptecon14clr2.htmlhttp://www.museum.state.il.us/RiverWeb/landings/Ambot/prehistory/mississippian/economy/subsistence.html -
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What happens if you only eat
corn? Maize has very low levels of the amino acid
lysine
Relying heavily on maize leads to niacindeficiency called pellagra
Pellagra has afflicted many maize eatingpopulations including Southerners in the USduring the depression in the 1930s
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How to avoid pellagra
Native Americans in what is now Mexico treatedmaize with lime water or fire ash water
This releases tryptophan from the maize which the
body can utilize in the production of niacin
Hopi Indians roasted maize which liberates niacin
Others harvested maize when it was immature andcontained more niacin
People who did not know to do this and relied onmaize suffered from pellagra
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How did people learn this?
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Reliance on a staple
Nutritional problems
Susceptibility to starvation
Crop disease
Drought
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Degenerative conditions
Osteoarthritis of articular surfaces of joints
and vertebral column
40% of hunter-gatherer adults
70% horticultural adults
Repetitive stress injury?
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Child growth and development
Horticultural children had decreased rate of
growth 0-5 years
Caught up to hunter-gatherer children afterage 10
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Child growth and development
cont. Dental hypoplasias
Deficiency in enamel thickness
Result of physiological stress
Position on tooth indicates age of stress
55% of hunter-gatherers have hypoplasias
80% of horticulturalists
Horticulturalists hypoplasias peak at age 2 year earlier than hunter-gatherer
Indicates earlier weaning and reliance on cereals asweaning foods
Continual food shortage??
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Life expectancy
Hunter-gatherer life expectancy at birth is 26 years
For horticulturalist19 years
13% of H-G died at less than 1 year 22% of horticulturalist
15 year old H-G had 23 more years lifeexpectancy
15 year old horticulturalist had 18 more years lifeexpectancy