Unit 1 Introduction to Environmental Science

How Human Populations have Changed Population: A specific species living in the same place. Human population has changed over long periods of time. It took all of human history to 1800 for the world population to reach 1 billion people.

How Human Populations have Changed During the 1900s (just 100 years) the population grew from 1.65 billion to 6 billion! Currently there are over 7 billion people on earth, and are expected to reach 8 billion in 2025.

How Human Populations have Changed * Hunter Gatherers Hunter-Gatherers: People how hunt and forage for food by collecting wild plants and following the movements of wild animals Most of human history was spent like this Small groups of people Nomadic (living life wandering) to find food Had a Strong Sense of the Earth - Only took from nature what they needed to survive

How Human Populations have Changed * How Hunter Gatherers Affected Environment Burned trees to prevent growth on prairies to make hunting bison easier Caused extinction of large animals like the giant sloth, mammoths, and saber-toothed tigers

How Human Populations have Changed * Agriculture Revolution (click for video) Agriculture: Is the raising of crops and livestock for food or for other products that are useful to humans. Began 10,000 years ago, people learned to grow crops and domesticate animals allowing them to remain in one place.

How Human Populations have Changed * How Agriculture Revolution affected the Environment 1. Allowed human populations to increase faster than ever before 2. Populations of humans began to concentrate in small areas increasing drastic changes to local environments. 3. The plants that we eat today are drastically different from the wild ancestors 4. Wetlands and forests replaced by farmland

How Human Populations have Changed * Agriculture Gives Rise to Cities Food Produced in country and consumed in cities Waste of populations concentrated in cities a. Sewage becomes a problem b. Plagues/Diseases spread easily