Chapter 6 – Human Population
Human Population: Approaching 7 Billion
1800 – World population reached a billion. Now nearly 7 billion
Doubling time – 70 divided by annual percentage growth rate.
Thomas Malthus – a) favoured population growth and b) argued that the pressure of
population growth on the availability of resources could lead to disaster.
Reason these predictions haven’t come true yet is because we have always had a
breakthrough: i.e.: technology.
The application of population ecology principles to the study of statistical change in human
populations is the focus of the social silence of demography.
Earth has a carrying capacity. Before estimates went from 1-2 billion people living
prosperously to 33 billion managing to live in extreme poverty – it is still unknown, as
humans have these major breakthroughs in history.
Demographers – study population size, density, distribution, age structure, sex ration and
rates of birth, death, immigration and emigration of humans, just as population ecologists
study these characteristics in other organisms.
Population density – # of people per unit area
Population density and distribution, age structure, sex ratios
Sex ratios: for every 100 females, 105 males born – may be because males are more prone
to death. Evolutionary aspect – different in other countries – China 135 for every 100
females, 200 for every 100 in UAE
Crude birth/death rate – number of deaths/births per 1000 individuals for a given time
Total fertility rate (TFR) – average number of children born per female member of a
population during her lifetime.
Replacement fertility – is the total fertility rate that keeps the size of a population
stable. For humans, replacement fertility is equal to a TFR of 2.1. Below this value,
population will shrink