8/12/2019 Anth 342 Chapter 4

1/63

Chapter 4: Demography

aka Population Studies or PopulationScience

The study of human populations Size

Composition

Distribution Causes and consequences of changes in those

characteristics

8/12/2019 Anth 342 Chapter 4

2/63

Demography is interdisciplinary

Many factors impact population

Demographers can be trained in

Sociology

Economics

Biology

Geography

History

Health sciences

ANTHROPOLOGY

8/12/2019 Anth 342 Chapter 4

3/63

Population measures

Fertility

Mortality

Migration

8/12/2019 Anth 342 Chapter 4

4/63

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

8/12/2019 Anth 342 Chapter 4

5/63

8/12/2019 Anth 342 Chapter 4

6/63

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

8/12/2019 Anth 342 Chapter 4

7/63

Industrialized countries

Contraceptive use and abortion most

important factors

8/12/2019 Anth 342 Chapter 4

8/63

Developing countries

Infecundity due to STDs, HIV/AIDS,

lactational amenoreah (Interbirth interval),

and postpartum abstinence (postpartumtaboo) most important factors

8/12/2019 Anth 342 Chapter 4

9/63

Fertility patterns

This implies that people in industrialized

countries want to limit their fertility and

people in developing countries are limitedby exogenous factors

8/12/2019 Anth 342 Chapter 4

10/63

Measures of fertility

Period rates

Cohort rates

8/12/2019 Anth 342 Chapter 4

11/63

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)

8/12/2019 Anth 342 Chapter 4

12/63

Period rates contd.

Most of these measures focus on women

15-49 years old. Why?

8/12/2019 Anth 342 Chapter 4

13/63

Cohort rates

Completed fertility rate (CFR) or completed

family size (CFS)

Number of live births to a woman who hascompleted reproduction (menopause)

8/12/2019 Anth 342 Chapter 4

14/63

Variation in fertility

Within a society or political entity

Between a society or political entity

Between men and women in the same

society

8/12/2019 Anth 342 Chapter 4

15/63

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

8/12/2019 Anth 342 Chapter 4

16/63

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?

8/12/2019 Anth 342 Chapter 4

17/63

8/12/2019 Anth 342 Chapter 4

18/63

Variation in mortality

Age

Sex

Socioeconomic status

8/12/2019 Anth 342 Chapter 4

19/63

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

8/12/2019 Anth 342 Chapter 4

20/63

Types of migration

In-migration (immigration)

Out-migration (emigration)

International vs. internal

8/12/2019 Anth 342 Chapter 4

21/63

Net migration

Difference between in- and out-migration

8/12/2019 Anth 342 Chapter 4

22/63

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

8/12/2019 Anth 342 Chapter 4

23/63

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

8/12/2019 Anth 342 Chapter 4

24/63

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

8/12/2019 Anth 342 Chapter 4

25/63

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

8/12/2019 Anth 342 Chapter 4

26/63

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

8/12/2019 Anth 342 Chapter 4

27/63

Demographic balancing equation

Shows the roles of fertility, mortality, and

migration in population change

Population =Birthsdeaths +immigrants-emigrants

Used in population projection

8/12/2019 Anth 342 Chapter 4

28/63

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

8/12/2019 Anth 342 Chapter 4

29/63

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

8/12/2019 Anth 342 Chapter 4

30/63

Other components

Sex

Race

Ethnicity

8/12/2019 Anth 342 Chapter 4

31/63

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

8/12/2019 Anth 342 Chapter 4

32/63

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

8/12/2019 Anth 342 Chapter 4

33/63

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

8/12/2019 Anth 342 Chapter 4

34/63

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

8/12/2019 Anth 342 Chapter 4

35/63

Demographic Transitions

Three types of demographic transitions

Fertility

Mortality

Health (also called Epidemiologic)

8/12/2019 Anth 342 Chapter 4

36/63

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

8/12/2019 Anth 342 Chapter 4

37/63

8/12/2019 Anth 342 Chapter 4

38/63

Theories of fertility transitions

Classical demographic theory

Economic models

Social models

Evolutionary models

8/12/2019 Anth 342 Chapter 4

39/63

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

8/12/2019 Anth 342 Chapter 4

40/63

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

8/12/2019 Anth 342 Chapter 4

41/63

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.

8/12/2019 Anth 342 Chapter 4

42/63

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

8/12/2019 Anth 342 Chapter 4

43/63

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

8/12/2019 Anth 342 Chapter 4

44/63

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?

8/12/2019 Anth 342 Chapter 4

45/63

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

8/12/2019 Anth 342 Chapter 4

46/63

Agriculture

Cultivation and herd animals

Domestication

Occurred worldwide about 12,000 years ago Mesopotamia

Levant

China

Indus valley

Mesoamerica

8/12/2019 Anth 342 Chapter 4

47/63

8/12/2019 Anth 342 Chapter 4

48/63

8/12/2019 Anth 342 Chapter 4

49/63

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

8/12/2019 Anth 342 Chapter 4

50/63

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

8/12/2019 Anth 342 Chapter 4

51/63

8/12/2019 Anth 342 Chapter 4

52/63

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

8/12/2019 Anth 342 Chapter 4

53/63

Social consequences

Population concentration

Storage of resources

Power differentials

All led to complex societies

Cities

Social stratification

8/12/2019 Anth 342 Chapter 4

54/63

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

8/12/2019 Anth 342 Chapter 4

55/63

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

8/12/2019 Anth 342 Chapter 4

56/63

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

8/12/2019 Anth 342 Chapter 4

57/63

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

8/12/2019 Anth 342 Chapter 4

58/63

How did people learn this?

8/12/2019 Anth 342 Chapter 4

59/63

Reliance on a staple

Nutritional problems

Susceptibility to starvation

Crop disease

Drought

8/12/2019 Anth 342 Chapter 4

60/63

Degenerative conditions

Osteoarthritis of articular surfaces of joints

and vertebral column

40% of hunter-gatherer adults

70% horticultural adults

Repetitive stress injury?

8/12/2019 Anth 342 Chapter 4

61/63

Child growth and development

Horticultural children had decreased rate of

growth 0-5 years

Caught up to hunter-gatherer children afterage 10

8/12/2019 Anth 342 Chapter 4

62/63

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??

8/12/2019 Anth 342 Chapter 4

63/63

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