Survival Curves L.O: to describe and explain the shape of the human population survival curve http://galen.metapath.org/popclk.html

Quick Check – What can you conclude about the populations of these four countries?

Quick Check – What can you conclude about the populations of these four countries? India’s population is expanding, while China is contracting, US appears stationary and Italy is contracting quite quickly.

Decreasing

What major developments affected population size? Agricultural development Development of trade and manufacturing – industrial revolution

Survival Curves A survival curve plots the number of people alive as a function of time. Typically it plots the percentage of a population still alive at different ages but it can also be used to plot the percentage of a population still alive following a particular event, such as a medical operation or the onset of a disease. The average life expectancy is the age at which: 50% if the individuals in a population are still alive. Life expectancy can be calculated from a survival curve, by finding this % and reading off the life expectancy.

What do these graphs tell you?

SURVIVAL CURVES Type I – applies to species that have a high survival rate in the young. Live out the most of their lifespan, and die in old age. Type II – applies to species that have a relatively constant death rate throughout their lifespan. Death is often from predation or disease. Type III – found in species that have many young, most of which die very early in their life. Most human populations have a type I survival curve. Where infant mortality is high, survival curves approach type III.

Complete the Survival Rates and Life Expectancy worksheet To Do: Complete the Survival Rates and Life Expectancy worksheet Draw a population pyramid for Ethiopia Now compare this pyramid to the pyramid of the UK that you have been given and answer the questions below: Is the population of Ethiopia: stable, increasing or decreasing? Is the population of the UK: stable, increasing or decreasing? What stage of the demographic transition model (DTM) do you think Ethiopia is in? Give reasons for your answer.