1. Why do populations rise or fall in particular places?
Thomas Malthus – An Essay on the Principles of Population.
The world’s population was increasing faster than the food supplies needed to sustain it.
Food supplies grow linearly, adding acreage and crops incrementally by year, whereas population grew exponentially, compounding on the year before.

2. Malthus and Predictions
Assumed food production is confined spatially and linearly – what people can eat within a country depends on what is grown in the country.
Assumptions were false.
Food consumption is not confined spatially.
Malthus did not foresee how globalization would aid the exchange of agricultural goods across the world.

3. Malthus’s Growth Rates
Today: 1 person = 1 unit of food
In 25 years: 2 persons = 2 units of food
In 50 years: 4 persons = 3 units of food
In 75 years: 8 persons = 4 units of food
In 100 years: 16 persons = 5 units of food
Malthus made predictions after England had become the first country to enter Stage 2 of the DTM.

4. Malthus and Predictions
Mercantilism, colonialism, and capitalism brought interaction among the Americas, Europe, Africa, Asia, and the Pacific.
New agricultural methods developed, and commodities and livestock diffused across oceans.
Ireland = Potato (1700s)

5. Malthus and Predictions
Neither is food production confined linearly.
Food production has grown exponentially as the acreage under cultivation expands, mechanization of agricultural production diffuses, improved strains of seed are developed, and more fertilizers are used.
In the 21st century, bioengineering continues to bring new hybrids.

6. Malthus and Predictions
Neo-Malthusians point out that human suffering is now occurring on a scale unimagined even by Malthus.
Neo-Malthusians argue that overpopulation must be addressed now.

7. Population Growth at World Scale
Every rate of growth has a doubling time.
When the growth rate is 10%, the doubling time is around seven years.
2000 years ago = 250 million
1650 = 500 million (16 centuries later)
1820 = 1 billion (170 years later)
1930 = 2 billion (110 years later)
1975 = 4 billion (45 years later)
Today world population is doubling in 51 years, and the slowdown in the estimated doubling rate is one of the bright spots in the problematic demographic picture.

8. Population Growth at a World Scale
Global growth rate is now down to 1.4%.
Today, the world’s population is about 6.4 billion, yielding an increase in world population that still exceeds 80 million annually.
Population growth rate will have to come down well below 1% to significantly slow down global population growth.

9. Population Growth at Regional & National Scale
Demographers point to the correlation between high growth rates and the low standing of women.
South Asia is the most important geographic region in the PGR picture.
Slowest growing countries lie in the economically wealthier areas of the world.

10. Population Growth at the Local Scale
Example: India
Some States record PGR far above the national average (mostly in the east and northeast-west of the country.
Other States in the west and southwest region, are growing much more slowly.
India is a federation of 28 States and 7 so-called Union Territories.
As in any federation, the will of the federal government cannot be forcibly imposed on the States.

11. India 1950s – Population planning program.
1970s – Forced sterilization of men with three or more children.
2004 – Gun license for sterilization.
Policy allows for a shotgun license in exchange for the sterilization of two people and a revolver license in exchange for the sterilization of five people.
Advertising and persuasion.