Chapter 9 The Human Population

9.1: Studying Human Populations Describe how the size and growth rate of the human population has changed in the last 200 years Define four properties that scientists use to predict population sizes Make predictions about population trends based on age structure Describe the four stages of the demographic transition Explain why different countries may be at different stages of the demographic transition

2 Categories for Countries: Countries are often grouped by demographers into 2 general categories: Developed countries—higher average incomes, slower population growth, and diverse industrial economies. Developing countries—lower average incomes, simple and agriculture-based economies, and rapid population growth.

Human Population Growth 1800’s: exponential growth due to… Increases in food production Improvements in hygiene (eg. clean water and safe sewage disposal) Industrial and scientific revolutions Discovery of vaccines in the 20th century Cannot continue…limited resources, competition, carrying capacity

Predicting Population Sizes (4) Age structure The distribution of ages in a specific population at a certain time. Graphed in a population pyramid (lab!) High growth rate more young than old Slow or no growth  even distribution of ages Survivorship The percentage of members of a group that are likely to survive to any given age. Survivorship curves: type I (most live to be very old), II (similar death rates at all ages), III (very poor, many children die)

Predicting Population Sizes (4) Fertility rates: the number of babies born each year per 1,000 women in a population. Also can calculate total fertility rate Considers “replacement level”: the avg. number of children each parent must have in order to “replace” themselves. Migration: mvmt. of individuals btwn. areas. Immigration (in) vs. Emigration (out)

Reasons for Increases in Human Population Growth (or decline)… Death rates decreased more rapidly than birth rates…causes??? Life expectancy (most affected by infant mortality); survivorship curve 1900 = age 40 w/ a high infant mortality rate 2000 = >age 67 (developed = 80+) w/ infant mortality at < 1/3 of the rate in 1900 Infant health is affected by… -parents’ access to education, food, fuel, and clean water Other threats?: density  increases in contagious diseases (e.g. AIDS, tuberculosis, Ebola)

HW!! Read through chapter 9  Pg. 239: The Demographic Transition Take notes over the “stages of transition” and “women and fertility” Checked in and discussed/questions tomorrow

9.2 Changing Population Trends Describe three problems caused by rapid human population growth Compare population growth problems in more-developed countries and less developed countries Analyze strategies countries may use to reduce their population growth Describe worldwide population projections into the next century

3 Problems…cause: rapid human population growth Primary Problem: environmental; over consumption of resources; infrastructure. 1. vegetation…ex.: fuelwood 2. water…used for drinking, washing, & sewage disposal: waterborne diseases such as dysentery, typhoid, and cholera; ex. Lima, Peru. 3. land…shortage of arable (A.V.) land (land that is used to grow crops); urbanization (A.V.); “suburban sprawl”.

Managing Development and Growth Strategies used include: family planning programs, economic incentives, legal punishments, public advertising, improvements in women’s status. Result: worldwide fertility rates are dropping! Demographers predict that by 2050, most countries will have replacement level fertility rates  world population growth will _____(?) World population = >7 billion and is still increasing.