04a - Demography

Demography

the study of human populations dynamics

Paleodemography

• demographic characteristics of past populations derived from skeletal or cemetery samples

• fundamental for understanding population changes in the past

Demographic Transition

Stage 1 - birth rate high, death rate high, natural increase stable or slow increase

Stage 2 - birth rate high, death rate falls rapidly, natural increase rapid

Stage 3 - birth rate falling, death rate falls more slowly, natural increase slows down

Stage 4 - birth rate low, death rate low, natural increase falling and then stable

Stage 5 - birth rate yet to be seen, death rate low, natural increase little change

TFR

total fertility rate

Replacement level fertility

• we need a TFR of 2.1 to maintain population

• we estimate we need a TFR of 4-5 in prehistory to maintain populations

Menarche

female’s very first menstrual period

Menopause

the ceasing of menstruation

PRLS

post reproductive lifespan

Preservation Bias

not all things are equally likely to preserve due to many factors:

• size

• material

• environment

• time

IBI - interbirth interval

• the time between 2 consecutive births

• influenced by food accessibility, breastfeeding, early embryo loss/miscarriages

IPI - inter pregnancy interval

time between birth of 1 child and conception of the next

• includes miscarriages

• does not include the period of gestation

Life expectancy

global life expectancy is expected to keep rising to reach 77 years in 2045-2050 and 83 years in 2095-2100

Life expectancy at birth

global life expectancy at birth, has risen from 48 years in 1950-1955 to 67 years in 2000-2005

Cause of death

• leading cause of death in history and prehistory to be infectious disease, causing an estimated 75% of deaths

• the leading causes of death today are non-communicable diseases

Motorcycle hump

a distinct, localized spike in a population’s mortality curve during late adolescence and early adulthood