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A Long Time Ago
Society developed when people began
to do individual jobs. This is called the "division of labor."
When people Eventually, people learned how to
write. Writing allowed people to pass their knowledge onto others. Sir
Isaac Newton once said, "If I have seen further than others, it is
because I have stood on the shoulders of giants." What Sir Isaac
meant was that his accomplishments were possible because he learned from
the people who came before him. Instant In the last two hundred years, scientists have concluded that humans have only lived on the earth for a short period of the earth's history. They believe the earth is about 4.6 billion years old. This estimate is based on radiometric age-dating. Certain elements emit energy; this is called radioactivity. Over time, the elements causing radioactivity decay. If an object has a half-life of one million years, half of the element causing radioactivity will decay over a period of one million years. Radiometric age-dating is not precise, but it does provide us with a vague estimate of the age of the earth. |
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History
began when humans learned to read and write. The first writing we know
of came from civilizations in Mesopotamia and Egypt about 5500 years ago.
People lived for thousands of years before this, but little changed from
generation to generation. People lived as nomads. Nomads are people who
have no permanent home. Men hunted animals and women gathered wild plants.
When there were no more animals to hunt or plants to gather, they moved
to a new place. 
do
only one job, they usually choose a job they enjoy and do well. Further,
when you do the same job over and over, you learn to do it very well.
The division of labor caused people to depend on one another and eventually
led to advanced civilizations.