Population Growth AAEC 3204 George Norton Agricultural and Applied Economics Virginia Tech
Objectives • Discuss nature of population growth in the world • Consider determinants and consequences of rapid population growth and urbanization
Population issues to be discussed • Basic facts about population growth • Consequences of population growth • Causes of population growth • Policies to influence population growth and rural to urban migration
Has population increased at a fairly constant rate since prehistoric times? B.C. Today
World Population • What is the present world population? • What is the current growth rate and is the growth rate currently at its historical peak?
12 11 10 9 8 7 6 5 4 3 2 1 0 Past and projected World population 1800 1850 1900 1950 2000 2050 2100 2150
When would world population double at the current growth rate? Is the growth rate likely to remain at 1.2 percent? Why or why not? 70/1.2 = 58 years
Why has population increased faster in developing countries today that it did in early stages of U.S. development?
Are population growth rates more likely to increase rather than decrease over the next 10 years? Decrease
When will the world population stop growing and at what population? Maybe in 2150 at 10.5-11.5 billion; By 2050, expect about 9 billion
Why does population grow when growth rates are declining? Recent rapid growth means young population with many in child bearing years
Let’s examine: • Determinants of birth rates • Economic factors important in affecting birth rates 3) Consequences of rapid population growth
Determinants of birth rates • Income (economic factors) • Culture and social factors • Birth control • Education • Religion • Wars
Why are economic factors important in affecting birth rates? • Children provide labor in agriculture • Children provide social security • Children are a consumption good • Income implies value of time so number of children • Quantity / quality tradeoff
In what sense is population growth a substitute for missing institutions and markets?
Missing Institutions and markets • Insurance • Medical • Life insurance • Disability • Natural disaster • Theft • Social security • Government • Employer
Gender bias • Culture and inheritance laws • Low female wages reduces opportunity cost of children • Education of females
Externalities • What externalities might be involved with fertility choices and why? • Costs of certain public goods such as schools and infrastructure might exceed private costs • Environmental effects • Family structure
Negative Food Difficult to educate Environment Age dependency Jobs Capital shallowing Investment diversion Positive Labor Economies of scale Market Intellectual base for ideas and innovations Effect on demand for technologies What are the consequences of rapid population growth?
What are some policies that influence population growth? • Policies for social and economic improvement • Social security system • Family planning • Female education
Urbanization also increasing with rural to urban migration • Nature of migration • Why migration occurs • Consequences • Policy implications
Rural to urban migration 1980’s and 90’s– population growth in LDC’s averaged 2.1% But, urban population growth averaged 3.5% (in many countries, 6 to 8%)
Why is rural to urban migration good and why is it bad? • Good • Labor for industry (efficient use of resources) • Education: costs and benefits • Larger markets • Bad • Unemployment • Housing & Public services • Environment
Why do people migrate from rural to urban areas? • Economic factors • Benefits of move • Costs of move • Planning horizon • Social & cultural factors
Who tends to migrate? Age of migrants? • Young Education of migrants? • Better educated Marital status of migrants? • Single
Harris-Todaro Model of Migration • Potential migrants evaluate the “potential” or expected gains from migration versus the costs • Expected gains: real income differential times the probability of receiving a job offer • Probability is inversely related to the rate of unemployment • Migration rates in excess of urban job growth rates are expected in this model
What is the urban informal sector? Why is the informal sector both good and bad for developing countries?
What policies can affect rural to urban migration? • Improve services in rural areas (education, health, etc.) • Remove bias in economic policies • Jobs in rural areas
Conclusions • Population growth and R-U migration have been rapid in developing countries in recent years • Many causes but several are economic and institutional • Effects are positive and negative • Public policies can influence pop growth and R-U migration rates