|A.D.1||World population at 200 million.|
|1750||World population at 791 million.|
|1798||Thomas Malthus publishes Essay on the Principle of Population.|
|1800||World population at 978 million.|
|1845||Irish potato famine.|
|1854||Henry David Thoreau publishes Walden.|
|1859||Charles Darwin publishes On the Origin of Species.|
|1864||George Perkins Marsh publishes Man and Nature.|
|1869||Ernst Haeckel first uses the term "ecology" in an address.|
The first official wildlife sanctuary is established at Lake Merritt|
Yellowstone, the world's first national park, is established (largely|
in northwestern Wyoming).
The oldest and largest nongovernmental environmental organiza-|
tion, Sierra Club, is created.
|1900||The Lacey Act, a landmark in federal regulation, is passed.|
|1900||World Population at 1.650 billion.|
The first federal wildlife refuge, Pelican Island, Florida, is estab-|
lished by President Theodore Roosevelt.