The Last 10,000 Years of Human History By 1810, population ~1 billion By 1922, population ~2 billion By 1959, population ~3 billion By 1974, population ~4 billion By 1987, population ~5 billion By 1999, population ~6 billion By 2017, population ~7.6 billion The present human population of the world is a little more than ______________.  In the last 50 years of the 20th Century, world population grew from ______ billion to over 6 billion.

The Human Population Today Growth rate = (birth rate) – (death rate) Human population grows by about 70 million people per year Present population of the world id 7.6 Billion The growth rate is 1.1% per year Doubling time = 200 years (In 2217 it will be 15.2) The growth rate of the world population equals ________________.

Future World Population

What about? Too many people? Crowding in cities Crime Pollution Illegal migration Disease Room for more people? Our entire world population could fit inside 42 km x 42 km square in 2017 (Isle of Man + Isle of Wight) Consider carrying capacity

Carrying Capacity How many people can Earth support? Increasing amounts of food can be produced People can migrate from areas of famine or poverty to less crowded or wealthier areas

Carrying Capacity Example of Rapa Nui (Easter Island) Isolated Pacific island with poor soil and little water Settled by 25-50 people from Polynesia 400AD Survived easily on chickens and yams, plenty of free time Developed elaborate competition between clans with Civilization peaked at 1650, with population of about 10,000

History Example of Rapa Nui (Easter Island) Reached by a Dutch ship in 1722 Found 2,000 people living in caves Primitive society and at war with each other. Rapa Nui’s carrying capacity had been drastically lowered by society’s actions: Transportation of moai had required cutting down trees Erosion of soil made yams scarce Lack of canoes made fishing difficult and escape impossible