Population, Urbanism & the Environment World population Currently 6.5 Billion Most of human history the population of the entire earth was 500 Million (1/2 billion) Demography The study of human population Through most of human history, families had many children because: Children were needed of the form Birth control was not reliable High death rates = many children did not reach adulthood Demographic terms Fertility Amount of childbearing in a population Several measurements of this Demographic terms (cont.) Crude birth rate Live births per 1,000 people each year High income nations e.g. U.S. = lower than average crude birth rate The lower the average income, the higher the population increase Demographic terms (Cont.) Fecundity rate Maximum possible childbearing Sex Ratio Males for every 100 females Zero Population growth (ZPG) Two people produce two people Maintains population at a steady state Malthusian theory Food increasing arithmetically Pop. Increasing geometrically Result : People reproducing beyond what the planet can support Out-stripping resources Poisoning the planet Demographic Transition Theory Population patterns reflect a society’s level of technological development