The Stone Age was a prehistoric time when people made tools from stone such as flint. It began when people created the first stone tools about 3.3 million years ago.  About 99% of human history happened during the Stone Age. It lasted for about 3.4 million years, and ended between 4,000 BC and 2,000 BC.
Archaeologists divide the Stone Age into three sections: Paleolithic ("old stone"), Mesolithic ("middle stone"), and Neolithic ("new stone").  During the Neolithic period, people invented farming and pottery, and started to care for animals like cows and pigs.
Sometime between 3000 BC and 2000 BC, people discovered the art of smelting (making metals). This probably happened in the Middle East. People used copper first, then learned how to make bronze. When people started using these metals instead of stone, the Stone Age ended and the Bronze Age began.
Some groups of people in Papua New Guinea continued to use Stone Age technology into the 20th century. They used stone-tipped weapons to kill animals for food and clothing. They made shelters using animal skin.
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