Humans have been on Earth for millions of years

Human Characteristics: Humans Change the World

For millions of years all humans, early and modern alike, had to find their own food. They spent a large part of each day gathering plants and hunting or scavenging animals. Then, within just the past 12,000 years, our species, Homo sapiens, made the transition to producing food and changing our surroundings. We have been so successful that we have inadvertently created a turning point in the history of life on Earth.

http://humanorigins.si.edu/human-characteristics/humans-change-world